Re: Question about MSM Driver

Re: Question about MSM Driver

[Rob Clark]

On Wed, Dec 11, 2019 at 6:22 AM ggermanres <ggermanres@gmail.com> wrote:
>
> Hello.
>
> I have question about MSM Driver.
>
> I using Dragonboard 410 with ili9881 display. This is hobby project. This display from xiaomi redmi 3x/4x. I made PCB board for connect them. I changed dts, created panel driver (this all on buildroot with my config). All ok. Run platform. I saw linux console. Freedreno (opengl test app) is working fine. But I saw flickering like on old monitor I saw from phone. I tried changing timings, but this helped a little bit (I used it from dtsi from xiaomi repository).
>
> I think this is with vsync problem. Your driver support DSI_VSYNC input? In panel driver I sent command for vblank, on oscilloscope I saw pulse on this pin 60Hz. I tried find path in your driver code, added some debug output in code with sync. I saw MDSS_DSI_0_TRIG_CTRL configured with support TE. But Its not helped for me.
>
> If you know something, tell me. Or how change driver to support DSI_VSYNC input.
>

I guess this is a command mode panel?  So you'd be caring about the TE
signal?  As far as I understand (from, iirc, jhugo) this was handled
by the hardware and not exposed to the driver on older devices.

If it is a video mode panel, the problem could be different (userspace
not waiting for pageflip event?)

BR,
-R
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Re: Question about MSM Driver

[ggermanres]

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Yes. This is DSI command to panel.

I saw same problem in 96boards.org discuss. On Android its all ok, but on
Linux flickering.

Yes, panel in video mode. Where is pageflip event in driver? Or where add
sleep/delay between update buffer? I think buffer copy by DMA (module) to
panel. But for this needed some request event (or irq). In this case I want
to try catch problem by adding software delay. And make decision about this
problem, it with display, hardware or with something else.

ср, 11 дек. 2019 г. в 19:52, Rob Clark <robdclark@gmail.com>:

> On Wed, Dec 11, 2019 at 6:22 AM ggermanres <ggermanres@gmail.com> wrote:
> >
> > Hello.
> >
> > I have question about MSM Driver.
> >
> > I using Dragonboard 410 with ili9881 display. This is hobby project.
> This display from xiaomi redmi 3x/4x. I made PCB board for connect them. I
> changed dts, created panel driver (this all on buildroot with my config).
> All ok. Run platform. I saw linux console. Freedreno (opengl test app) is
> working fine. But I saw flickering like on old monitor I saw from phone. I
> tried changing timings, but this helped a little bit (I used it from dtsi
> from xiaomi repository).
> >
> > I think this is with vsync problem. Your driver support DSI_VSYNC input?
> In panel driver I sent command for vblank, on oscilloscope I saw pulse on
> this pin 60Hz. I tried find path in your driver code, added some debug
> output in code with sync. I saw MDSS_DSI_0_TRIG_CTRL configured with
> support TE. But Its not helped for me.
> >
> > If you know something, tell me. Or how change driver to support
> DSI_VSYNC input.
> >
>
> I guess this is a command mode panel?  So you'd be caring about the TE
> signal?  As far as I understand (from, iirc, jhugo) this was handled
> by the hardware and not exposed to the driver on older devices.
>
> If it is a video mode panel, the problem could be different (userspace
> not waiting for pageflip event?)
>
> BR,
> -R
>

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