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Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller

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  Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Sekhar Nori <nsekhar@ti.com> - 2016-10-15 19:50 +0200
    Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-10-15 21:50 +0200
    Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-10-17 08:00 +0200
      Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Sekhar Nori <nsekhar@ti.com> - 2016-10-17 09:20 +0200
        Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-10-17 09:30 +0200
        Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-10-17 09:40 +0200
          Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-10-17 13:50 +0200
            Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-10-17 14:40 +0200
              Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-10-17 14:50 +0200
              Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-10-17 16:10 +0200
                Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Sekhar Nori <nsekhar@ti.com> - 2016-10-20 12:10 +0200
                  Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-10-20 12:30 +0200
                    Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller Sekhar Nori <nsekhar@ti.com> - 2016-10-20 12:40 +0200

#1501334 — Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller

On Wednesday 05 October 2016 06:35 PM, Bartosz Golaszewski wrote:
> From: Karl Beldan <kbeldan@baylibre.com>
> 
> Add pins used by the LCD controller and a disabled LCDC node to be
> reused in device trees including da850.dtsi.
> 
> Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
> [Bartosz:
>   - added the commit description
>   - changed the dt node name to a generic one
>   - added a da850-specific compatible string
>   - removed the tilcdc,panel node
>   - moved the pins definitions to da850.dtsi as suggested by
>     Sekhar Nori (was in: da850-lcdk.dts)]
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  arch/arm/boot/dts/da850.dtsi | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
> index f79e1b9..32908ae 100644
> --- a/arch/arm/boot/dts/da850.dtsi
> +++ b/arch/arm/boot/dts/da850.dtsi

> @@ -399,6 +420,14 @@
>  				<&edma0 0 1>;
>  			dma-names = "tx", "rx";
>  		};
> +
> +		display: display@213000 {
> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";

This should instead be:

compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";

as the closest match should appear first in the list.

> +			reg = <0x213000 0x1000>;
> +			interrupt-parent = <&intc>

No need of specifying the interrupt-parent as it is assumed to be that
from the parent node (soc) if left unspecified.

I made these two fixes locally and pushed the two patches in this series
to v4.10/dt branch of my tree (for URL see MAINTAINERS). Can you take a
look and make sure I did not mess anything up?

Regards,
Sekhar

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#1501352

2016-10-15 19:42 GMT+02:00 Sekhar Nori <nsekhar@ti.com>:
> On Wednesday 05 October 2016 06:35 PM, Bartosz Golaszewski wrote:
>> From: Karl Beldan <kbeldan@baylibre.com>
>>
>> Add pins used by the LCD controller and a disabled LCDC node to be
>> reused in device trees including da850.dtsi.
>>
>> Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
>> [Bartosz:
>>   - added the commit description
>>   - changed the dt node name to a generic one
>>   - added a da850-specific compatible string
>>   - removed the tilcdc,panel node
>>   - moved the pins definitions to da850.dtsi as suggested by
>>     Sekhar Nori (was in: da850-lcdk.dts)]
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>> ---
>>  arch/arm/boot/dts/da850.dtsi | 29 +++++++++++++++++++++++++++++
>>  1 file changed, 29 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>> index f79e1b9..32908ae 100644
>> --- a/arch/arm/boot/dts/da850.dtsi
>> +++ b/arch/arm/boot/dts/da850.dtsi
>
>> @@ -399,6 +420,14 @@
>>                               <&edma0 0 1>;
>>                       dma-names = "tx", "rx";
>>               };
>> +
>> +             display: display@213000 {
>> +                     compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>
> This should instead be:
>
> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>
> as the closest match should appear first in the list.
>
>> +                     reg = <0x213000 0x1000>;
>> +                     interrupt-parent = <&intc>
>
> No need of specifying the interrupt-parent as it is assumed to be that
> from the parent node (soc) if left unspecified.
>
> I made these two fixes locally and pushed the two patches in this series
> to v4.10/dt branch of my tree (for URL see MAINTAINERS). Can you take a
> look and make sure I did not mess anything up?
>

Looks good, thanks!

Bartosz Golaszewski

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#1501619

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On 15/10/16 20:42, Sekhar Nori wrote:

>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>> index f79e1b9..32908ae 100644
>> --- a/arch/arm/boot/dts/da850.dtsi
>> +++ b/arch/arm/boot/dts/da850.dtsi
> 
>> @@ -399,6 +420,14 @@
>>  				<&edma0 0 1>;
>>  			dma-names = "tx", "rx";
>>  		};
>> +
>> +		display: display@213000 {
>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
> 
> This should instead be:
> 
> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
> 
> as the closest match should appear first in the list.

Actually I don't think that's correct. The LCDC on da850 is not
compatible with the LCDC on AM335x. I think it should be just
"ti,da850-tilcdc".

 Tomi

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#1501643

On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
> On 15/10/16 20:42, Sekhar Nori wrote:
> 
>>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>>> index f79e1b9..32908ae 100644
>>> --- a/arch/arm/boot/dts/da850.dtsi
>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>
>>> @@ -399,6 +420,14 @@
>>>  				<&edma0 0 1>;
>>>  			dma-names = "tx", "rx";
>>>  		};
>>> +
>>> +		display: display@213000 {
>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>
>> This should instead be:
>>
>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>
>> as the closest match should appear first in the list.
> 
> Actually I don't think that's correct. The LCDC on da850 is not
> compatible with the LCDC on AM335x. I think it should be just
> "ti,da850-tilcdc".

So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
the case, I wonder how the patch passed testing. Bartosz?

Thanks,
Sekhar

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#1501645

2016-10-17 9:12 GMT+02:00 Sekhar Nori <nsekhar@ti.com>:
> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>> On 15/10/16 20:42, Sekhar Nori wrote:
>>
>>>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>>>> index f79e1b9..32908ae 100644
>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>
>>>> @@ -399,6 +420,14 @@
>>>>                             <&edma0 0 1>;
>>>>                     dma-names = "tx", "rx";
>>>>             };
>>>> +
>>>> +           display: display@213000 {
>>>> +                   compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>
>>> This should instead be:
>>>
>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>
>>> as the closest match should appear first in the list.
>>
>> Actually I don't think that's correct. The LCDC on da850 is not
>> compatible with the LCDC on AM335x. I think it should be just
>> "ti,da850-tilcdc".
>
> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
> the case, I wonder how the patch passed testing. Bartosz?
>

DA850 uses revision 1 of the IP while am33xx is equipped with rev 2.
The driver reads the appropriate register, detects the revision and
sets the corresponding field in struct tilcdc_drm_private in
tilcdc_load().

Thanks,
Bartosz

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#1501648

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On 17/10/16 10:12, Sekhar Nori wrote:
> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>> On 15/10/16 20:42, Sekhar Nori wrote:
>>
>>>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>>>> index f79e1b9..32908ae 100644
>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>
>>>> @@ -399,6 +420,14 @@
>>>>  				<&edma0 0 1>;
>>>>  			dma-names = "tx", "rx";
>>>>  		};
>>>> +
>>>> +		display: display@213000 {
>>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>
>>> This should instead be:
>>>
>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>
>>> as the closest match should appear first in the list.
>>
>> Actually I don't think that's correct. The LCDC on da850 is not
>> compatible with the LCDC on AM335x. I think it should be just
>> "ti,da850-tilcdc".
> 
> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
> the case, I wonder how the patch passed testing. Bartosz?

AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
similar, but different.

The driver gets the version number from LCDC's register, and acts based
on that, so afaik the compatible string doesn't really affect the
functionality (as long as it matches).

But even if it works with the current driver, I don't think
"ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.

 Tomi

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#1501906

Hello,

On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
> On 17/10/16 10:12, Sekhar Nori wrote:
>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>>> On 15/10/16 20:42, Sekhar Nori wrote:
>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
>>>>> b/arch/arm/boot/dts/da850.dtsi
>>>>> index f79e1b9..32908ae 100644
>>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>>> @@ -399,6 +420,14 @@
>>>>>  				<&edma0 0 1>;
>>>>>  			dma-names = "tx", "rx";
>>>>>  		};
>>>>> +
>>>>> +		display: display@213000 {
>>>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>> 
>>>> This should instead be:
>>>> 
>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>> 
>>>> as the closest match should appear first in the list.
>>> 
>>> Actually I don't think that's correct. The LCDC on da850 is not
>>> compatible with the LCDC on AM335x. I think it should be just
>>> "ti,da850-tilcdc".
>> 
>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
>> the case, I wonder how the patch passed testing. Bartosz?
> 
> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
> similar, but different.
> 
> The driver gets the version number from LCDC's register, and acts based
> on that, so afaik the compatible string doesn't really affect the
> functionality (as long as it matches).
> 
> But even if it works with the current driver, I don't think
> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.

If the hardware provides IP revision information, how about just "ti,lcdc" ?

-- 
Regards,

Laurent Pinchart

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#1501942

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On 17/10/16 14:40, Laurent Pinchart wrote:
> Hello,
> 
> On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
>> On 17/10/16 10:12, Sekhar Nori wrote:
>>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>>>> On 15/10/16 20:42, Sekhar Nori wrote:
>>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
>>>>>> b/arch/arm/boot/dts/da850.dtsi
>>>>>> index f79e1b9..32908ae 100644
>>>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>>>> @@ -399,6 +420,14 @@
>>>>>>  				<&edma0 0 1>;
>>>>>>  			dma-names = "tx", "rx";
>>>>>>  		};
>>>>>> +
>>>>>> +		display: display@213000 {
>>>>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>>>
>>>>> This should instead be:
>>>>>
>>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>>>
>>>>> as the closest match should appear first in the list.
>>>>
>>>> Actually I don't think that's correct. The LCDC on da850 is not
>>>> compatible with the LCDC on AM335x. I think it should be just
>>>> "ti,da850-tilcdc".
>>>
>>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
>>> the case, I wonder how the patch passed testing. Bartosz?
>>
>> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
>> similar, but different.
>>
>> The driver gets the version number from LCDC's register, and acts based
>> on that, so afaik the compatible string doesn't really affect the
>> functionality (as long as it matches).
>>
>> But even if it works with the current driver, I don't think
>> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.
> 
> If the hardware provides IP revision information, how about just "ti,lcdc" ?

Maybe, and I agree that's the "correct" way, but looking at the history,
it's not just once or twice when we've suddenly found out some
difference or bug or such in an IP revision, or the integration to a
SoC, that can't be found based on the IP revision.

That's why I feel it's usually safer to have the SoC revision there in
the compatible string.

That said, we have only a few different old SoCs with LCDC (compared to,
say, OMAP DSS) so in this case perhaps just "ti,lcdc" would be fine.

 Tomi

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#1501946

Hi Tomi,

On Monday 17 Oct 2016 15:29:23 Tomi Valkeinen wrote:
> On 17/10/16 14:40, Laurent Pinchart wrote:
> > On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
> >> On 17/10/16 10:12, Sekhar Nori wrote:
> >>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
> >>>> On 15/10/16 20:42, Sekhar Nori wrote:
> >>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
> >>>>>> b/arch/arm/boot/dts/da850.dtsi
> >>>>>> index f79e1b9..32908ae 100644
> >>>>>> --- a/arch/arm/boot/dts/da850.dtsi
> >>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
> >>>>>> @@ -399,6 +420,14 @@
> >>>>>>  				<&edma0 0 1>;
> >>>>>>  			dma-names = "tx", "rx";
> >>>>>>  		};
> >>>>>> +
> >>>>>> +		display: display@213000 {
> >>>>>> +			compatible = "ti,am33xx-tilcdc", "ti,da850-
tilcdc";
> >>>>> 
> >>>>> This should instead be:
> >>>>> 
> >>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
> >>>>> 
> >>>>> as the closest match should appear first in the list.
> >>>> 
> >>>> Actually I don't think that's correct. The LCDC on da850 is not
> >>>> compatible with the LCDC on AM335x. I think it should be just
> >>>> "ti,da850-tilcdc".
> >>> 
> >>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
> >>> the case, I wonder how the patch passed testing. Bartosz?
> >> 
> >> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
> >> similar, but different.
> >> 
> >> The driver gets the version number from LCDC's register, and acts based
> >> on that, so afaik the compatible string doesn't really affect the
> >> functionality (as long as it matches).
> >> 
> >> But even if it works with the current driver, I don't think
> >> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.
> > 
> > If the hardware provides IP revision information, how about just "ti,lcdc"
> > ?
>
> Maybe, and I agree that's the "correct" way, but looking at the history,
> it's not just once or twice when we've suddenly found out some
> difference or bug or such in an IP revision, or the integration to a
> SoC, that can't be found based on the IP revision.
> 
> That's why I feel it's usually safer to have the SoC revision there in
> the compatible string.
> 
> That said, we have only a few different old SoCs with LCDC (compared to,
> say, OMAP DSS) so in this case perhaps just "ti,lcdc" would be fine.

You obviously know more than I do on this topic so I'll trust your opinion. If 
the version register isn't enough I'm fine with multiple compatible strings.

-- 
Regards,

Laurent Pinchart

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#1501995

2016-10-17 14:29 GMT+02:00 Tomi Valkeinen <tomi.valkeinen@ti.com>:
> On 17/10/16 14:40, Laurent Pinchart wrote:
>> Hello,
>>
>> On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
>>> On 17/10/16 10:12, Sekhar Nori wrote:
>>>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>>>>> On 15/10/16 20:42, Sekhar Nori wrote:
>>>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
>>>>>>> b/arch/arm/boot/dts/da850.dtsi
>>>>>>> index f79e1b9..32908ae 100644
>>>>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>>>>> @@ -399,6 +420,14 @@
>>>>>>>                                  <&edma0 0 1>;
>>>>>>>                          dma-names = "tx", "rx";
>>>>>>>                  };
>>>>>>> +
>>>>>>> +                display: display@213000 {
>>>>>>> +                        compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>>>>
>>>>>> This should instead be:
>>>>>>
>>>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>>>>
>>>>>> as the closest match should appear first in the list.
>>>>>
>>>>> Actually I don't think that's correct. The LCDC on da850 is not
>>>>> compatible with the LCDC on AM335x. I think it should be just
>>>>> "ti,da850-tilcdc".
>>>>
>>>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
>>>> the case, I wonder how the patch passed testing. Bartosz?
>>>
>>> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
>>> similar, but different.
>>>
>>> The driver gets the version number from LCDC's register, and acts based
>>> on that, so afaik the compatible string doesn't really affect the
>>> functionality (as long as it matches).
>>>
>>> But even if it works with the current driver, I don't think
>>> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.
>>
>> If the hardware provides IP revision information, how about just "ti,lcdc" ?
>
> Maybe, and I agree that's the "correct" way, but looking at the history,
> it's not just once or twice when we've suddenly found out some
> difference or bug or such in an IP revision, or the integration to a
> SoC, that can't be found based on the IP revision.
>
> That's why I feel it's usually safer to have the SoC revision there in
> the compatible string.
>
> That said, we have only a few different old SoCs with LCDC (compared to,
> say, OMAP DSS) so in this case perhaps just "ti,lcdc" would be fine.
>
>  Tomi
>

I Sekhar is ok with this, I'll send a follow-up patch for that.

Thanks,
Bartosz

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#1504739

On Monday 17 October 2016 07:31 PM, Bartosz Golaszewski wrote:
> 2016-10-17 14:29 GMT+02:00 Tomi Valkeinen <tomi.valkeinen@ti.com>:
>> On 17/10/16 14:40, Laurent Pinchart wrote:
>>> Hello,
>>>
>>> On Monday 17 Oct 2016 10:33:58 Tomi Valkeinen wrote:
>>>> On 17/10/16 10:12, Sekhar Nori wrote:
>>>>> On Monday 17 October 2016 11:26 AM, Tomi Valkeinen wrote:
>>>>>> On 15/10/16 20:42, Sekhar Nori wrote:
>>>>>>>> diff --git a/arch/arm/boot/dts/da850.dtsi
>>>>>>>> b/arch/arm/boot/dts/da850.dtsi
>>>>>>>> index f79e1b9..32908ae 100644
>>>>>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>>>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>>>>>> @@ -399,6 +420,14 @@
>>>>>>>>                                  <&edma0 0 1>;
>>>>>>>>                          dma-names = "tx", "rx";
>>>>>>>>                  };
>>>>>>>> +
>>>>>>>> +                display: display@213000 {
>>>>>>>> +                        compatible = "ti,am33xx-tilcdc", "ti,da850-tilcdc";
>>>>>>>
>>>>>>> This should instead be:
>>>>>>>
>>>>>>> compatible = "ti,da850-tilcdc", "ti,am33xx-tilcdc";
>>>>>>>
>>>>>>> as the closest match should appear first in the list.
>>>>>>
>>>>>> Actually I don't think that's correct. The LCDC on da850 is not
>>>>>> compatible with the LCDC on AM335x. I think it should be just
>>>>>> "ti,da850-tilcdc".
>>>>>
>>>>> So if "ti,am33xx-tilcdc" is used, the display wont work at all? If thats
>>>>> the case, I wonder how the patch passed testing. Bartosz?
>>>>
>>>> AM3 has "version 2" of LCDC, whereas DA850 is v1. They are quite
>>>> similar, but different.
>>>>
>>>> The driver gets the version number from LCDC's register, and acts based
>>>> on that, so afaik the compatible string doesn't really affect the
>>>> functionality (as long as it matches).
>>>>
>>>> But even if it works with the current driver, I don't think
>>>> "ti,am33xx-tilcdc" and "ti,da850-tilcdc" are compatible in the HW level.
>>>
>>> If the hardware provides IP revision information, how about just "ti,lcdc" ?
>>
>> Maybe, and I agree that's the "correct" way, but looking at the history,
>> it's not just once or twice when we've suddenly found out some
>> difference or bug or such in an IP revision, or the integration to a
>> SoC, that can't be found based on the IP revision.
>>
>> That's why I feel it's usually safer to have the SoC revision there in
>> the compatible string.

I agree with Tomi here. Lets keep the soc part number in the compatible
string. More often than not, some undocumented, undiscovered issue pops
up over time. Its much safer to have the SoC revision in there.

>>
>> That said, we have only a few different old SoCs with LCDC (compared to,
>> say, OMAP DSS) so in this case perhaps just "ti,lcdc" would be fine.
>>
>>  Tomi
>>
> 
> I Sekhar is ok with this, I'll send a follow-up patch for that.

Per me, compatible property is an ordered list precisely for the reason
that things should continue to "work" with as closely matched driver as
possible. So even if someone is running a kernel which does not
recognize "ti,da850-tilcdc", it should still be able to probe the driver
based on "ti,am33xx-tilcdc" and provide as close to full functionality
as possible.

That said, I will not insist on keeping it around if Tomi is
uncomfortable. And having read the binding documentation accepted by
Jyri, it actually says the compatible property should be __one of__
"ti,am33xx-tilcdc" or "ti,da850-tilcdc".

Thanks,
Sekhar

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#1504748

[Multipart message — attachments visible in raw view] — view raw

On 20/10/16 13:07, Sekhar Nori wrote:

> Per me, compatible property is an ordered list precisely for the reason
> that things should continue to "work" with as closely matched driver as
> possible. So even if someone is running a kernel which does not
> recognize "ti,da850-tilcdc", it should still be able to probe the driver
> based on "ti,am33xx-tilcdc" and provide as close to full functionality
> as possible.
> 
> That said, I will not insist on keeping it around if Tomi is
> uncomfortable. And having read the binding documentation accepted by
> Jyri, it actually says the compatible property should be __one of__
> "ti,am33xx-tilcdc" or "ti,da850-tilcdc".

Well, they are just not compatible as far as I know. If the LCDC on
DA850 would be identified as AM335x LCDC, and used as such, it would not
work at all. They have different registers, AM335x LCDC has registers
that do not exist on DA850.

With our driver it happens to work, because the driver looks at the IP
revision in the registers, and then decides that this IP is not AM335x
LCDC even if the dts says so. But I see that as a driver "feature",
nothing that the .dts can depend on.

Perhaps it might work the other way around, using DA850 driver on
AM335x, as DA850 LCDC is a kind of subset of AM335x LCDC. But I'm not
sure even about that.

 Tomi

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#1504753

On Thursday 20 October 2016 03:51 PM, Tomi Valkeinen wrote:
> On 20/10/16 13:07, Sekhar Nori wrote:
> 
>> Per me, compatible property is an ordered list precisely for the reason
>> that things should continue to "work" with as closely matched driver as
>> possible. So even if someone is running a kernel which does not
>> recognize "ti,da850-tilcdc", it should still be able to probe the driver
>> based on "ti,am33xx-tilcdc" and provide as close to full functionality
>> as possible.
>>
>> That said, I will not insist on keeping it around if Tomi is
>> uncomfortable. And having read the binding documentation accepted by
>> Jyri, it actually says the compatible property should be __one of__
>> "ti,am33xx-tilcdc" or "ti,da850-tilcdc".
> 
> Well, they are just not compatible as far as I know. If the LCDC on
> DA850 would be identified as AM335x LCDC, and used as such, it would not
> work at all. They have different registers, AM335x LCDC has registers
> that do not exist on DA850.
> 
> With our driver it happens to work, because the driver looks at the IP
> revision in the registers, and then decides that this IP is not AM335x
> LCDC even if the dts says so. But I see that as a driver "feature",
> nothing that the .dts can depend on.
> 
> Perhaps it might work the other way around, using DA850 driver on
> AM335x, as DA850 LCDC is a kind of subset of AM335x LCDC. But I'm not
> sure even about that.

Alright, thanks for the detailed explanation. I dropped the "ti,am33xx-
tilcdc" from the list and here is the updated patch I am queuing for
reference.

Thanks,
Sekhar

--8<--
Author:     Karl Beldan <kbeldan@baylibre.com>
AuthorDate: Wed Oct 5 15:05:32 2016 +0200
Commit:     Sekhar Nori <nsekhar@ti.com>
CommitDate: Thu Oct 20 15:57:21 2016 +0530

    ARM: dts: da850: add a node for the LCD controller
    
    Add pins used by the LCD controller and a disabled LCDC node to be
    reused in device trees including da850.dtsi.
    
    Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
    [Bartosz:
      - added the commit description
      - changed the dt node name to a generic one
      - added a da850-specific compatible string
      - removed the tilcdc,panel node
      - moved the pins definitions to da850.dtsi as suggested by
        Sekhar Nori (was in: da850-lcdk.dts)]
    Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
    [nsekhar@ti.com: fix compatible property and remove interrupt-parent]
    Signed-off-by: Sekhar Nori <nsekhar@ti.com>

diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
index f79e1b91c680..901d5c98d5f0 100644
--- a/arch/arm/boot/dts/da850.dtsi
+++ b/arch/arm/boot/dts/da850.dtsi
@@ -186,6 +186,27 @@
 					0xc 0x88888888 0xffffffff
 				>;
 			};
+			lcd_pins: pinmux_lcd_pins {
+				pinctrl-single,bits = <
+					/*
+					 * LCD_D[2], LCD_D[3], LCD_D[4], LCD_D[5],
+					 * LCD_D[6], LCD_D[7]
+					 */
+					0x40 0x22222200 0xffffff00
+					/*
+					 * LCD_D[10], LCD_D[11], LCD_D[12], LCD_D[13],
+					 * LCD_D[14], LCD_D[15], LCD_D[0], LCD_D[1]
+					 */
+					0x44 0x22222222 0xffffffff
+					/* LCD_D[8], LCD_D[9] */
+					0x48 0x00000022 0x000000ff
+
+					/* LCD_PCLK */
+					0x48 0x02000000 0x0f000000
+					/* LCD_AC_ENB_CS, LCD_VSYNC, LCD_HSYNC */
+					0x4c 0x02000022 0x0f0000ff
+				>;
+			};
 
 		};
 		edma0: edma@0 {
@@ -399,6 +420,13 @@
 				<&edma0 0 1>;
 			dma-names = "tx", "rx";
 		};
+
+		display: display@213000 {
+			compatible = "ti,da850-tilcdc";
+			reg = <0x213000 0x1000>;
+			interrupts = <52>;
+			status = "disabled";
+		};
 	};
 	aemif: aemif@68000000 {
 		compatible = "ti,da850-aemif";

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