linux-kernel - Re: [PATCH v1 2/2] media: camss: Avoid overwriting vfe clock rates for 8250

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Message-ID: <cc737b05-4476-4ded-9d1c-5924cfbce316@linaro.org>
Date: Fri, 2 Aug 2024 23:20:17 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Jordan Crouse <jorcrous@...zon.com>, linux-media@...r.kernel.org
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, Robert Foss
 <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] media: camss: Avoid overwriting vfe clock rates
 for 8250

On 02/08/2024 16:24, Jordan Crouse wrote:
> On sm8250 targets both the csid and vfe subsystems share a number of
> clocks. Commit b4436a18eedb ("media: camss: add support for SM8250 camss")
> reorganized the initialization sequence so that VFE gets initialized first
> but a side effect of that was that the CSID subsystem came in after and
> overwrites the set frequencies on the shared clocks.
> 
> Empty the frequency tables for the shared clocks in the CSID resources so
> they won't overwrite the clock rates that the VFE has already set.
> 
> Signed-off-by: Jordan Crouse <jorcrous@...zon.com>
> ---
> 
>   drivers/media/platform/qcom/camss/camss.c | 21 +++++++++++++++------
>   1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c
> index 51b1d3550421..d78644c3ebe9 100644
> --- a/drivers/media/platform/qcom/camss/camss.c
> +++ b/drivers/media/platform/qcom/camss/camss.c
> @@ -915,6 +915,15 @@ static const struct camss_subdev_resources csiphy_res_8250[] = {
>   	}
>   };
>   
> +/*
> + * Both CSID and VFE use some of the same vfe clocks and both
> + * should prepare/enable them but only the VFE subsystem should be in charge
> + * of setting the clock rates.
> + *
> + * Set the frequency tables for those clocks in the CSID resources to
> + * be empty so the csid subsystem doesn't overwrite the clock rates that the
> + * VFE already set.
> + */
>   static const struct camss_subdev_resources csid_res_8250[] = {
>   	/* CSID0 */
>   	{
> @@ -922,8 +931,8 @@ static const struct camss_subdev_resources csid_res_8250[] = {
>   		.clock = { "vfe0_csid", "vfe0_cphy_rx", "vfe0", "vfe0_areg", "vfe0_ahb" },
>   		.clock_rate = { { 400000000 },
>   				{ 400000000 },
> -				{ 350000000, 475000000, 576000000, 720000000 },
> -				{ 100000000, 200000000, 300000000, 400000000 },
> +				{ 0 },
> +				{ 0 },
>   				{ 0 } },
>   		.reg = { "csid0" },
>   		.interrupt = { "csid0" },
> @@ -939,8 +948,8 @@ static const struct camss_subdev_resources csid_res_8250[] = {
>   		.clock = { "vfe1_csid", "vfe1_cphy_rx", "vfe1", "vfe1_areg", "vfe1_ahb" },
>   		.clock_rate = { { 400000000 },
>   				{ 400000000 },
> -				{ 350000000, 475000000, 576000000, 720000000 },
> -				{ 100000000, 200000000, 300000000, 400000000 },
> +				{ 0 },
> +				{ 0 },
>   				{ 0 } },
>   		.reg = { "csid1" },
>   		.interrupt = { "csid1" },
> @@ -956,7 +965,7 @@ static const struct camss_subdev_resources csid_res_8250[] = {
>   		.clock = { "vfe_lite_csid", "vfe_lite_cphy_rx", "vfe_lite",  "vfe_lite_ahb" },
>   		.clock_rate = { { 400000000 },
>   				{ 400000000 },
> -				{ 400000000, 480000000 },
> +				{ 0 },
>   				{ 0 } },
>   		.reg = { "csid2" },
>   		.interrupt = { "csid2" },
> @@ -973,7 +982,7 @@ static const struct camss_subdev_resources csid_res_8250[] = {
>   		.clock = { "vfe_lite_csid", "vfe_lite_cphy_rx", "vfe_lite",  "vfe_lite_ahb" },
>   		.clock_rate = { { 400000000 },
>   				{ 400000000 },
> -				{ 400000000, 480000000 },
> +				{ 0 },
>   				{ 0 } },
>   		.reg = { "csid3" },
>   		.interrupt = { "csid3" },

Hi Jordan.

Thanks for your patch. Just looking at the clocks you are zeroing here, 
I think _probably_ these zeroized clocks can be removed from the CSID 
set entirely.

Could you investigate that ?

Also please add

Fixes: b4436a18eedb ("media: camss: add support for SM8250 camss") and 
cc stable@...r.kernel.org

---
bod