Re: [PATCH v5 7/7] ARM: dts: rockchip: Specify rk3288-veyron-minnie's display timings

Heiko Stübner
2019-07-11T21:28:21Z

Am Montag, 1. April 2019, 19:17:24 CEST schrieb Douglas Anderson:
> Just like we did for rk3288-veyron-chromebook, we want to be able to
> use one of the fixed PLLs in the system to make the pixel clock for
> minnie.
>
> Specifying these timings matches us with how the display is used on
> the downstream Chrome OS kernel. See https://crrev.com/c/323211.
>
> Unlike what we did for rk3288-veyron-chromebook, this CL actually
> changes the timings (though not the pixel clock) that is used when
> using the upstream kernel. Booting up a minnie shows that it ended up
> with a 66.67 MHz pixel clock but it was still using the
> porches/blankings it would have wanted for a 72.5 MHz pixel clock.
>
> NOTE: compared to the downstream kernel, this seems to cause a
> slightly different result reported in the 'modetest' command on a
> Chromebook. The downstream kernel shows:
> 1280x800 60 1280 1298 1330 1351 800 804 822 830 66667
>
> With this patch we have:
> 1280x800 59 1280 1298 1330 1351 800 804 822 830 66666
>
> Specifically modetest was reporting 60 Hz on the downstream kernel but
> the upstream kernel does the math and comesup with 59 (because we
> actually achieve 59.45 Hz). Also upstream doesn't round the Hz up
> when converting to kHz--it seems to truncate.
>
> ALSO NOTE: when I look at the EDID from the datasheet, I see:
> -hsync -vsync
> ...but it seems like we've never actually run with that so I've
> continued leaving that out.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

applied for 5.4

Thanks
Heiko