Re: [PATCH v2] drm/msm/dpu: always program dsc active bits

[Abhinav Kumar]

On 4/14/2023 12:48 AM, Marijn Suijten wrote:
> Capitalize DSC in the title, as discussed in v1.
>
> On 2023-04-13 08:56:41, Kuogee Hsieh wrote:
> > In current code, the DSC active bits are written only if cfg->dsc is set.
> > However, for displays which are hot-pluggable, there can be a use-case
> > of disconnecting a DSC supported sink and connecting a non-DSC sink.
> >
> > For those cases we need to clear DSC active bits during tear down.
> >
> > Changes in V2:
> > 1) correct commit text as suggested
> > 2) correct Fixes commit id
> > 3) add FIXME comment
> >
> > Fixes: 77f6da90487c ("drm/msm/disp/dpu1: Add DSC support in hw_ctl")
> > Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> > Reviewed-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
>
> By default git send-email should pick this up in the CC line...  but I
> had to download this patch from lore once again.

Yes, I think what happened here is, he didnt git am the prev rev and 
make changes on top of that so git send-email didnt pick up. We should 
fix that process.

> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
> > index bbdc95c..1651cd7 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
> > @@ -541,10 +541,10 @@ static void dpu_hw_ctl_intf_cfg_v1(struct dpu_hw_ctl *ctx,
> >   	if (cfg->merge_3d)
> >   		DPU_REG_WRITE(c, CTL_MERGE_3D_ACTIVE,
> >   			      BIT(cfg->merge_3d - MERGE_3D_0));
> > -	if (cfg->dsc) {
> > -		DPU_REG_WRITE(&ctx->hw, CTL_FLUSH, DSC_IDX);
> > -		DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
> > -	}
> > +
> > +	/* FIXME: fix reset_intf_cfg to handle teardown of dsc */
>
> There's more wrong than just moving (not "fix"ing) this bit of code into
> reset_intf_cfg.  And this will have to be re-wrapped in `if (cfg->dsc)`
> again by reverting this patch.  Perhaps that can be explained, or link
> to Abhinav's explanation to make it clear to readers what this FIXME
> actually means?  Let's wait for Abhinav and Dmitry to confirm the
> desired communication here.
>
> https://lore.kernel.org/linux-arm-msm/ec045d6b-4ffd-0f8c-4011-8db45edc6978@xxxxxxxxxxx/

Yes, I am fine with linking this explanation in the commit text and 
mentioning that till thats fixed, we need to go with this solution. The 
FIXME itself is fine, I will work on it and I remember this context well.

> - Marijn
>
> > +	DPU_REG_WRITE(&ctx->hw, CTL_FLUSH, DSC_IDX);
> > +	DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
> >   }
> >   
> >   static void dpu_hw_ctl_intf_cfg(struct dpu_hw_ctl *ctx,
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project