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Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock

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  Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Srinivas Kandagatla <srinivas.kandagatla@linaro.org> - 2016-02-23 18:30 +0100
    Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Georgi Djakov <georgi.djakov@linaro.org> - 2016-02-23 19:50 +0100
      Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Andy Gross <andy.gross@linaro.org> - 2016-02-23 20:10 +0100
        Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Georgi Djakov <georgi.djakov@linaro.org> - 2016-02-24 11:40 +0100
      Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Srinivas Kandagatla <srinivas.kandagatla@linaro.org> - 2016-02-23 20:30 +0100
        Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock Georgi Djakov <georgi.djakov@linaro.org> - 2016-02-23 21:20 +0100

#1340892 — Re: [PATCH] arm64: dts: msm8916: Move smem below hwlock

On 23/02/16 17:21, Georgi Djakov wrote:
> When the SMEM is probed it defers as it depends on the hardware lock, which
> is not available yet. But the SMD bus and RPM regulators and clocks depend
> on SMEM and they defer too. The problem with this is that the order of
> registering the devices is not optimal and also we may end with messed
> up serial console as the RPM clocks are not registered yet..
I noticed the same issue but was wondering why would we end up with 
messed up serial console?

Could you add more details on why serial console is messed up?

I thought, serial driver has nothing to do with the rpm clocks directly!

--srini
>
> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> ---
>   arch/arm64/boot/dts/qcom/msm8916.dtsi |   19 ++++++++++---------
>   1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> index 7705207872a5..c497c7b1ae70 100644
> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> @@ -113,15 +113,6 @@
>   		};
>   	};
>
> -	smem {
> -		compatible = "qcom,smem";
> -
> -		memory-region = <&smem_mem>;
> -		qcom,rpm-msg-ram = <&rpm_msg_ram>;
> -
> -		hwlocks = <&tcsr_mutex 3>;
> -	};
> -
>   	soc: soc {
>   		#address-cells = <1>;
>   		#size-cells = <1>;
> @@ -512,6 +503,16 @@
>   		};
>   	};
>
> +	smem {
> +		compatible = "qcom,smem";
> +
> +		memory-region = <&smem_mem>;
> +		qcom,rpm-msg-ram = <&rpm_msg_ram>;
> +
> +		hwlocks = <&tcsr_mutex 3>;
> +	};
> +
> +
>   	smd {
>   		compatible = "qcom,smd";
>
> --
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>

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#1340941

On 23.02.16 г. 19:29, Srinivas Kandagatla wrote:
> 
> 
> On 23/02/16 17:21, Georgi Djakov wrote:
>> When the SMEM is probed it defers as it depends on the hardware lock, which
>> is not available yet. But the SMD bus and RPM regulators and clocks depend
>> on SMEM and they defer too. The problem with this is that the order of
>> registering the devices is not optimal and also we may end with messed
>> up serial console as the RPM clocks are not registered yet..
> I noticed the same issue but was wondering why would we end up with messed up serial console?
> 
> Could you add more details on why serial console is messed up?
> 
> I thought, serial driver has nothing to do with the rpm clocks directly!
> 

If we don't have the rpm clocks registered, the uart clock is an orphan
and when clk_get_rate() is called on orphan clocks it returns 0 as rate.
In our case the msm_serial driver calls clk_get_rate() and gets 0 rate
as the parent rpm clock has not registered yet. The result is that the
baudrate is set incorrectly.

BR,
Georgi

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#1340955

On Tue, Feb 23, 2016 at 08:47:56PM +0200, Georgi Djakov wrote:
> On 23.02.16 г. 19:29, Srinivas Kandagatla wrote:
> > 
> > 
> > On 23/02/16 17:21, Georgi Djakov wrote:
> >> When the SMEM is probed it defers as it depends on the hardware lock, which
> >> is not available yet. But the SMD bus and RPM regulators and clocks depend
> >> on SMEM and they defer too. The problem with this is that the order of
> >> registering the devices is not optimal and also we may end with messed
> >> up serial console as the RPM clocks are not registered yet..
> > I noticed the same issue but was wondering why would we end up with messed up serial console?
> > 
> > Could you add more details on why serial console is messed up?
> > 
> > I thought, serial driver has nothing to do with the rpm clocks directly!
> > 
> 
> If we don't have the rpm clocks registered, the uart clock is an orphan
> and when clk_get_rate() is called on orphan clocks it returns 0 as rate.
> In our case the msm_serial driver calls clk_get_rate() and gets 0 rate
> as the parent rpm clock has not registered yet. The result is that the
> baudrate is set incorrectly.

This isn't a probe defer issue w/ the SMEM and hwspinlock.  That works properly.
This is an issue with the msm_serial either not probe deferring to wait for the
rpm clocks or not handling the case of the clk framework giving us a 'bogus'
clock.  Can we queue off the clk_get_rate being 0 to probe defer for the rpm
clocks? (although that is hacky).

Regards,

Andy

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#1341789

On 02/23/2016 09:03 PM, Andy Gross wrote:
> On Tue, Feb 23, 2016 at 08:47:56PM +0200, Georgi Djakov wrote:
>> On 23.02.16 г. 19:29, Srinivas Kandagatla wrote:
>>>
>>>
>>> On 23/02/16 17:21, Georgi Djakov wrote:
>>>> When the SMEM is probed it defers as it depends on the hardware lock, which
>>>> is not available yet. But the SMD bus and RPM regulators and clocks depend
>>>> on SMEM and they defer too. The problem with this is that the order of
>>>> registering the devices is not optimal and also we may end with messed
>>>> up serial console as the RPM clocks are not registered yet..
>>> I noticed the same issue but was wondering why would we end up with messed up serial console?
>>>
>>> Could you add more details on why serial console is messed up?
>>>
>>> I thought, serial driver has nothing to do with the rpm clocks directly!
>>>
>>
>> If we don't have the rpm clocks registered, the uart clock is an orphan
>> and when clk_get_rate() is called on orphan clocks it returns 0 as rate.
>> In our case the msm_serial driver calls clk_get_rate() and gets 0 rate
>> as the parent rpm clock has not registered yet. The result is that the
>> baudrate is set incorrectly.
> 
> This isn't a probe defer issue w/ the SMEM and hwspinlock.  That works properly.

Ok, agree.

> This is an issue with the msm_serial either not probe deferring to wait for the
> rpm clocks or not handling the case of the clk framework giving us a 'bogus'
> clock.  Can we queue off the clk_get_rate being 0 to probe defer for the rpm
> clocks? (although that is hacky).

The proper solution would be to handle this in the clock framework.

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#1340967

On 23/02/16 18:47, Georgi Djakov wrote:
> On 23.02.16 г. 19:29, Srinivas Kandagatla wrote:
>>
>>
>> On 23/02/16 17:21, Georgi Djakov wrote:
>>> When the SMEM is probed it defers as it depends on the hardware lock, which
>>> is not available yet. But the SMD bus and RPM regulators and clocks depend
>>> on SMEM and they defer too. The problem with this is that the order of
>>> registering the devices is not optimal and also we may end with messed
>>> up serial console as the RPM clocks are not registered yet..
>> I noticed the same issue but was wondering why would we end up with messed up serial console?
>>
>> Could you add more details on why serial console is messed up?
>>
>> I thought, serial driver has nothing to do with the rpm clocks directly!
>>
>
> If we don't have the rpm clocks registered, the uart clock is an orphan
> and when clk_get_rate() is called on orphan clocks it returns 0 as rate.
Shouldn't the actual uart clk provider registration fail/defer probe due 
to missing parent in this case?

--srini
> In our case the msm_serial driver calls clk_get_rate() and gets 0 rate
> as the parent rpm clock has not registered yet. The result is that the
> baudrate is set incorrectly.
>
> BR,
> Georgi
>

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#1340993

On 23.02.16 г. 21:28, Srinivas Kandagatla wrote:
> 
> 
> On 23/02/16 18:47, Georgi Djakov wrote:
>> On 23.02.16 г. 19:29, Srinivas Kandagatla wrote:
>>>
>>>
>>> On 23/02/16 17:21, Georgi Djakov wrote:
>>>> When the SMEM is probed it defers as it depends on the hardware lock, which
>>>> is not available yet. But the SMD bus and RPM regulators and clocks depend
>>>> on SMEM and they defer too. The problem with this is that the order of
>>>> registering the devices is not optimal and also we may end with messed
>>>> up serial console as the RPM clocks are not registered yet..
>>> I noticed the same issue but was wondering why would we end up with messed up serial console?
>>>
>>> Could you add more details on why serial console is messed up?
>>>
>>> I thought, serial driver has nothing to do with the rpm clocks directly!
>>>
>>
>> If we don't have the rpm clocks registered, the uart clock is an orphan
>> and when clk_get_rate() is called on orphan clocks it returns 0 as rate.
> Shouldn't the actual uart clk provider registration fail/defer probe due to missing parent in this case?
> 

Yes, this is a known issue and people are currently working on it.
http://www.spinics.net/lists/linux-clk/msg00065.html
http://www.spinics.net/lists/arm-kernel/msg475910.html

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