Re: [PATCH v2 2/2] ARM: dts: da850-lcdk: specify the maximum pixel clock rate for tilcdc

From	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/2] ARM: dts: da850-lcdk: specify the maximum pixel clock rate for tilcdc
Date	2016-11-29 13:00 +0100
Message-ID	<sIPeO-7XO-39@gated-at.bofh.it> (permalink)
References	<sIt4B-1Zr-7@gated-at.bofh.it> <sIt4B-1Zr-15@gated-at.bofh.it> <sIOiJ-7oC-3@gated-at.bofh.it>
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2016-11-29 11:53 GMT+01:00 Sekhar Nori <nsekhar@ti.com>:
> On Monday 28 November 2016 05:45 PM, Bartosz Golaszewski wrote:
>> Due to memory throughput constraints any display mode for which the
>> pixel clock rate exceeds the recommended value of 37500 KHz must be
>> filtered out.
>
> I think there might be more reasons than memory throughput constraints
> for the reasoning behind 37.5Mhz cap on pixel clock. Why not just refer
> to the datasheet section that places this constraint so we know its a
> hardware restriction.
>
>>
>> Specify the max-pixelclock property for the display node for
>> da850-lcdk.
>>
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>> ---
>>  arch/arm/boot/dts/da850-lcdk.dts | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm/boot/dts/da850-lcdk.dts b/arch/arm/boot/dts/da850-lcdk.dts
>> index d864f11..1283263 100644
>> --- a/arch/arm/boot/dts/da850-lcdk.dts
>> +++ b/arch/arm/boot/dts/da850-lcdk.dts
>> @@ -285,6 +285,7 @@
>>
>>  &display {
>>       status = "okay";
>> +     max-pixelclock = <37500>;
>
> Should this not be in da850.dtsi since its an SoC imposed constraint? If
> a board needs narrower constraint, it can override it. But I guess most
> well designed boards will just hit the SoC constraint.
>

Both issues fixed in v3.

Thanks,
Bartosz Golaszewski

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[PATCH v2 2/2] ARM: dts: da850-lcdk: specify the maximum pixel clock rate for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-11-28 13:20 +0100
  Re: [PATCH v2 2/2] ARM: dts: da850-lcdk: specify the maximum pixel  clock rate for tilcdc Sekhar Nori <nsekhar@ti.com> - 2016-11-29 12:00 +0100
    Re: [PATCH v2 2/2] ARM: dts: da850-lcdk: specify the maximum pixel  clock rate for tilcdc Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-11-29 13:00 +0100

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