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SubjectRe: [Freedreno] [PATCH 02/11] drm/msm/dpu: use the actual lm maximum width instead of a hardcoded value
Le sam. 20 mai 2023 à 22:49, Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> a écrit :
>
> On 20/04/2023 20:47, Jeykumar Sankaran wrote:
> >
> >
> > On 4/19/2023 3:23 PM, Dmitry Baryshkov wrote:
> >> On 19/04/2023 17:41, Arnaud Vrac wrote:
> >>> This avoids using two LMs instead of one when the display width is lower
> >>> than the maximum supported value. For example on MSM8996/MSM8998, the
> >>> actual maxwidth is 2560, so we would use two LMs for 1280x720 or
> >>> 1920x1080 resolutions, while one is enough.
> >>>
> >>> Signed-off-by: Arnaud Vrac <avrac@freebox.fr>
> >>
> >> While this looks correct (and following what we have in 4.4), later
> >> vendor kernels specify the topology explicitly. Probably we should
> >> check this with the hw guys, because it might be the following case:
> >> even though a single LM can supply the mode, it will spend more power
> >> compared to two LMs.
> >>
> >>
> > Yes. 2 LM split will allow the HW to run in lower mdp core clock. Can
> > you maintain the split_threshold in the hw catalog until per mode
> > topology is available?
>
> I don't think it warrants the trouble, unless we have a real usecase
> when the device is short of LMs.
>
> Arnaud, I'll mark this patch as Rejected for now, unless it fixes an LM
> shortage for your platform.

It's fine, if I remember correctly I wrote this patch because display
wouldn't work before I fixed the LM pairings on msm8998, but now it's
not a requirement anymore.

>
> >
> > Jeykumar S
> >>> ---
> >>> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 10 +++++-----
> >>> 1 file changed, 5 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> >>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> >>> index 1dc5dbe585723..dd2914726c4f6 100644
> >>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> >>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> >>> @@ -53,8 +53,6 @@
> >>> #define IDLE_SHORT_TIMEOUT 1
> >>> -#define MAX_HDISPLAY_SPLIT 1080
> >>> -
> >>> /* timeout in frames waiting for frame done */
> >>> #define DPU_ENCODER_FRAME_DONE_TIMEOUT_FRAMES 5
> >>> @@ -568,10 +566,12 @@ static struct msm_display_topology
> >>> dpu_encoder_get_topology(
> >>> */
> >>> if (intf_count == 2)
> >>> topology.num_lm = 2;
> >>> - else if (!dpu_kms->catalog->caps->has_3d_merge)
> >>> - topology.num_lm = 1;
> >>> + else if (dpu_kms->catalog->caps->has_3d_merge &&
> >>> + dpu_kms->catalog->mixer_count > 0 &&
> >>> + mode->hdisplay > dpu_kms->catalog->mixer[0].sblk->maxwidth)
> >>> + topology.num_lm = 2;
> >>> else
> >>> - topology.num_lm = (mode->hdisplay > MAX_HDISPLAY_SPLIT) ? 2
> >>> : 1;
> >>> + topology.num_lm = 1;
> >>> if (crtc_state->ctm)
> >>> topology.num_dspp = topology.num_lm;
> >>>
> >>
>
> --
> With best wishes
> Dmitry
>

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