[PATCH] drm/msm/dpu: correct clk bit for WB2 block

[Abhinav Kumar]

Sorry for the delay in getting back on this. There was quite a bit of 
history digging I had to do myself to give a certain response.


On 10/9/2023 10:11 AM, Dmitry Baryshkov wrote:
> On sc7280 there are two clk bits for WB2: control and status. While
> programming the VBIF params of WB, the driver should be toggling the
> former bit, while the sc7280_mdp struct lists the latter one.
> 

No, this is not correct. Both are control bits. But for the context of 
where this is being used today, that is setting the VBIF OT limit, we 
should be using the VBIF_CLI one. So the below change itself is correct 
but not the commit text.

We need to make the same change on sm8250 WB2 as well as this register 
is present there too. In fact, anything >=msm8994 for setting VBIF OT 
for WB2 we should be using VBIF_CLI bits of register MDP_CLK_CTRL2 
(offset 0x2bc).

For anything >=sm8550, we need to use WB_2_CLK_CTRL present within the 
WB block and not the one in the top.

Hence for this change, we can do below:

-> update the commit text to indicate both are control bits but for the 
vbif ot context we should using the corrected one
-> if you can also add sm8250 in the same change i can ack it and pick it up

Have you re-validated WB with this change? If not, let me know I shall 
while picking this up for -fixes.

> Correct that to ensure proper programming sequence for WB2 on sc7280.
> 
> Fixes: 3ce166380567 ("drm/msm/dpu: add writeback support for sc7280")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> index 3b5061c4402a..9195cb996f44 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> @@ -25,7 +25,7 @@ static const struct dpu_mdp_cfg sc7280_mdp = {
>   		[DPU_CLK_CTRL_DMA0] = { .reg_off = 0x2ac, .bit_off = 8 },
>   		[DPU_CLK_CTRL_DMA1] = { .reg_off = 0x2b4, .bit_off = 8 },
>   		[DPU_CLK_CTRL_DMA2] = { .reg_off = 0x2c4, .bit_off = 8 },
> -		[DPU_CLK_CTRL_WB2] = { .reg_off = 0x3b8, .bit_off = 24 },
> +		[DPU_CLK_CTRL_WB2] = { .reg_off = 0x2bc, .bit_off = 16 },
>   	},
>   };
>