Question about MSM Driver

[Rob Clark]

On Wed, Dec 11, 2019 at 6:22 AM ggermanres <ggermanres at 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