[PATCH 3/3] ARM: dts: Add display timing node to exynos5250-arndale.dts
Vikas Sajjan
vikas.sajjan at linaro.org
Tue May 14 23:39:09 EST 2013
Thanks, we test and resend v2 patchset.
On 14 May 2013 18:55, Steffen Trumtrar <s.trumtrar at pengutronix.de> wrote:
> Hi!
>
> On Tue, May 14, 2013 at 06:40:00PM +0530, Vikas Sajjan wrote:
> > Hi Steffen Trumtrar and Sascha Hauer,
> >
> > Olof and Tomasz Figa have a concern in putting "display-timings" as root
> > node in device tree file.
> >
> >
> > On 10 May 2013 13:45, Vikas Sajjan <vikas.sajjan at linaro.org> wrote:
> >
> > > HI Tomasz,
> > >
> > >
> > > On 10 May 2013 13:03, Tomasz Figa <tomasz.figa at gmail.com> wrote:
> > >
> > >> On Friday 10 of May 2013 11:57:34 Vikas Sajjan wrote:
> > >> > Hi Olof,
> > >> >
> > >> > On 10 May 2013 11:51, Vikas Sajjan <vikas.sajjan at linaro.org> wrote:
> > >> > > Hi Olof,
> > >> > >
> > >> > > On 10 May 2013 11:08, Olof Johansson <olof at lixom.net> wrote:
> > >> > >> 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/c
> > >> > >>
> ommit/?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.
> > >> > >>
> > >> > >> I referred this "
> > >> >
> > >> > Documentation/devicetree/bindings/video/display-timing.txt" for
> example
> > >> >
> > >> > here it dosen't mention about whether display timings
> node
> > >> > can be placed at the root of the device tree or NOT.
> > >> > Not sure how we should be placing the node then.
> > >>
> > >> I think this is pretty obvious.
> > >>
> > >> Imagine a bit more complex case: a board has two video outputs (let's
> say
> > >> FIMD0 and FIMD1), each connected to a completely different display.
> This
> > >> means that each display needs different timings.
> > >>
> > >> How would you know which timings to use if all of them were be placed
> > >> under the root node?
> > >>
> > >> so what do you think, how should we modify this patch so that it
> > > belongs to a specific video outputs.
> > >
> > >
> >
> > So what do you think, how should we modify this patch so that it
> belongs
> > to a specific video outputs.
> >
> Something like
>
> &fimd {
> display-timings {
> timing0: timing at 0 {
> /* 2560x1600 DP panel */
> clock-frequency = <50000>;
> hactive = <2560>;
> vactive = <1600>;
> hfront-porch = <48>;
> (...)
> };
> };
> };
>
> Would be correct, if fimd is the output on which the display is connected.
> The fimd driver than has to utilize of_get_display_timings,
> of_get_fb_videomode
> or something like that.
>
> Regards,
> Steffen
>
> --
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>
--
Thanks and Regards
Vikas Sajjan
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