linux-kernel - Re: [PATCH v12 01/10] drm/msm/dpu: set DSC flush bit correctly at MDP CTL flush register

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Message-ID: <hkuonozf7gll3dd3bp6otdu6dspyrn633yokfx7sckqjs6tx2k@7nu77thwfaxs>
Date:   Mon, 22 May 2023 23:07:54 +0200
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Kuogee Hsieh <quic_khsieh@...cinc.com>,
        dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, swboyd@...omium.org, dianders@...omium.org,
        vkoul@...nel.org, daniel@...ll.ch, airlied@...il.com,
        agross@...nel.org, andersson@...nel.org, quic_abhinavk@...cinc.com,
        quic_jesszhan@...cinc.com, quic_sbillaka@...cinc.com,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v12 01/10] drm/msm/dpu: set DSC flush bit correctly at
 MDP CTL flush register

On 2023-05-22 23:18:02, Dmitry Baryshkov wrote:
> On 22/05/2023 22:30, Kuogee Hsieh wrote:
> > DSC flush bit is the bit 22 of CTL flush register. BIT(22) is expected
> > to be written to CTL flush register to indicates that DSC is ready for
> > flush. However 0x22 (BIT(1) and BIT(5)) was written mistakenly at current
> 
> DSC_IDX is 22, not 0x22.
> 
> > implementation. Fix this problem by writing BIT(22) to CTL flush register
> > for DSC to work properly.

Perhaps this whole comment needs a rewrite anyway, instead of pointing
out grammar errors and confusion:

    The DSC CTL_FLUSH register should be programmed with the 22th bit
    (DSC_IDX) to flush the DSC hardware blocks, not the literal value of
    22 (which corresponds to flushing VIG1, VIG2 and RGB1 instead).

Patch contents are good though, thanks!

- Marijn

> > Changes in V12:
> > -- split this patch out of "separate DSC flush update out of interface"
> > 
> > Fixes: 77f6da90487c ("drm/msm/disp/dpu1: Add DSC support in hw_ctl")
> > Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > 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 4f7cfa9..69d0ea2 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
> > @@ -525,7 +525,7 @@ static void dpu_hw_ctl_intf_cfg_v1(struct dpu_hw_ctl *ctx,
> >   		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(&ctx->hw, CTL_FLUSH, BIT(DSC_IDX));
> >   		DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
> >   	}
> >   }
> 
> -- 
> With best wishes
> Dmitry
>