linux-kernel - Re: [PATCH v3 04/15] drm/msm/dpu: decide right side per last bit

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Message-ID: <4uzsmtbeoilcodnlbnbst2t2gfbhaucpzne2bzwavdeawmqs4q@u33sixkksfls>
Date: Thu, 9 Jan 2025 14:14:52 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jun Nie <jun.nie@...aro.org>
Cc: Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 04/15] drm/msm/dpu: decide right side per last bit

On Thu, Jan 09, 2025 at 12:35:48PM +0800, Jun Nie wrote:
> Jessica Zhang <quic_jesszhan@...cinc.com> 于2025年1月9日周四 07:41写道：
> >
> >
> >
> > On 12/19/2024 2:09 PM, Dmitry Baryshkov wrote:
> > > On Thu, Dec 19, 2024 at 03:49:22PM +0800, Jun Nie wrote:
> > >> decide right side of a pair per last bit, in case of multiple
> > >> mixer pairs.
> > >
> > > Proper English sentences, please. Also describe why, not what.
> >
> > Hi Jun,
> >
> > Can we also add a note in the commit message on why the last bit check
> > works?
> 
> Sure. How about this?
> 
>     Currently we only support one pair of mixer, so counter's
>     non-zero value is enough to mark the right one. There will
>     be case with multiple mixer pairs, so let's use the last bit to
>     mark the right mixer in a mixer pair. If the last bit is set, it
>     marks the right mixer in the pair, it's left mixer otherwise.

You are not marking the right mixer, so it is not suitable.

> 
> >
> > Thanks,
> >
> > Jessica Zhang
> >
> > >
> > >>
> > >> Signed-off-by: Jun Nie <jun.nie@...aro.org>
> > >> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > >> ---
> > >>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 5 ++---
> > >>   1 file changed, 2 insertions(+), 3 deletions(-)
> > >>
> > >> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > >> index 7191b1a6d41b3..41c9d3e3e3c7c 100644
> > >> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > >> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > >> @@ -369,11 +369,10 @@ static void _dpu_crtc_setup_blend_cfg(struct dpu_crtc_mixer *mixer,
> > >>   static void _dpu_crtc_program_lm_output_roi(struct drm_crtc *crtc)
> > >>   {
> > >>      struct dpu_crtc_state *crtc_state;
> > >> -    int lm_idx, lm_horiz_position;
> > >> +    int lm_idx;
> > >>
> > >>      crtc_state = to_dpu_crtc_state(crtc->state);
> > >>
> > >> -    lm_horiz_position = 0;
> > >>      for (lm_idx = 0; lm_idx < crtc_state->num_mixers; lm_idx++) {
> > >>              const struct drm_rect *lm_roi = &crtc_state->lm_bounds[lm_idx];
> > >>              struct dpu_hw_mixer *hw_lm = crtc_state->mixers[lm_idx].hw_lm;
> > >> @@ -384,7 +383,7 @@ static void _dpu_crtc_program_lm_output_roi(struct drm_crtc *crtc)
> > >>
> > >>              cfg.out_width = drm_rect_width(lm_roi);
> > >>              cfg.out_height = drm_rect_height(lm_roi);
> > >> -            cfg.right_mixer = lm_horiz_position++;
> > >> +            cfg.right_mixer = lm_idx & 0x1;
> > >>              cfg.flags = 0;
> > >>              hw_lm->ops.setup_mixer_out(hw_lm, &cfg);
> > >>      }
> > >>
> > >> --
> > >> 2.34.1
> > >>
> > >
> > > --
> > > With best wishes
> > > Dmitry
> >

-- 
With best wishes
Dmitry