[PATCH 3/3] ARM: dts: Add display timing node to exynos5250-arndale.dts

[Olof Johansson]

On Thu, May 9, 2013 at 7:55 PM, Vikas Sajjan <vikas.sajjan at linaro.org> wrote:
> Hi Tomasz,
>
>
> On 10 May 2013 05:35, Tomasz Figa <tomasz.figa at gmail.com> wrote:
>>
>> Hi Vikas,
>>
>> On Wednesday 08 of May 2013 11:31:34 Vikas Sajjan wrote:
>> > Adds display timing node for a DP panel to Arndale Board DTS file
>> >
>> > Signed-off-by: Vikas Sajjan <vikas.sajjan at linaro.org>
>> > ---
>> >  arch/arm/boot/dts/exynos5250-arndale.dts |   16 ++++++++++++++++
>> >  1 file changed, 16 insertions(+)
>> >
>> > diff --git a/arch/arm/boot/dts/exynos5250-arndale.dts
>> > b/arch/arm/boot/dts/exynos5250-arndale.dts index f68b820..c831a5c
>> > 100644
>> > --- a/arch/arm/boot/dts/exynos5250-arndale.dts
>> > +++ b/arch/arm/boot/dts/exynos5250-arndale.dts
>> > @@ -459,4 +459,20 @@
>> >               samsung,lane-count = <4>;
>> >       };
>> >
>> > +     display-timings {
>> > +             native-mode = <&timing0>;
>> > +             timing0: timing at 0 {
>> > +                     /* 2560x1600 DP panel */
>> > +                     clock-frequency = <50000>;
>> > +                     hactive = <2560>;
>> > +                     vactive = <1600>;
>> > +                     hfront-porch = <48>;
>> > +                     hback-porch = <80>;
>> > +                     hsync-len = <32>;
>> > +                     vback-porch = <16>;
>> > +                     vfront-porch = <8>;
>> > +                     vsync-len = <6>;
>> > +             };
>> > +     };
>>
>> What display are those timings used for? Shouldn't they be placed inside
>> node of that display?
>>
>
> This timing information will be used parsed by the FIMD probe with the help
> of "Video Helper function"  as done in this link
>
> https://git.kernel.org/cgit/linux/kernel/git/daeinki/drm-exynos.git/commit/?h=exynos-drm-next&id=7f4596f4aebcc9fcf2d50d3fe398508d710c4dd0

That function passes in a device node pointer to the FIMD device node,
and only looks for a display-timings node under there. Tomasz is
right, as far as I can tell.

Placing display timings at the root of the device tree seems completely wrong.

> Please refer to this patch which is used for exynos4412-origen and
> exynos5250-smdk5250 respectively in similar way
>
> https://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/commit/?h=for-next&id=0207775d6ff7e6a6eddb9931f9328f0f0173a338
>
> https://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/commit/?h=for-next&id=06c460b73f75894cabfb1f5277f27cddbc92745c

That needs to be fixed up as well, thanks for pointing it out.


-Olof