From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vikas Sajjan Subject: Re: [PATCH 3/3] ARM: dts: Add display timing node to exynos5250-arndale.dts Date: Fri, 10 May 2013 13:45:27 +0530 Message-ID: References: <1367992894-20198-1-git-send-email-vikas.sajjan@linaro.org> <1853757.ubr759t9No@flatron> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2144475363372547759==" Return-path: In-Reply-To: <1853757.ubr759t9No@flatron> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Tomasz Figa , s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, Philipp Zabel Cc: "linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , InKi Dae , "kgene.kim" , Sylwester Nawrocki List-Id: devicetree@vger.kernel.org --===============2144475363372547759== Content-Type: multipart/alternative; boundary=089e01494164311b4b04dc58c605 --089e01494164311b4b04dc58c605 Content-Type: text/plain; charset=ISO-8859-1 HI Tomasz, On 10 May 2013 13:03, Tomasz Figa wrote: > On Friday 10 of May 2013 11:57:34 Vikas Sajjan wrote: > > Hi Olof, > > > > On 10 May 2013 11:51, Vikas Sajjan wrote: > > > Hi Olof, > > > > > > On 10 May 2013 11:08, Olof Johansson wrote: > > >> On Thu, May 9, 2013 at 7:55 PM, Vikas Sajjan > > >> > > >> > > >> wrote: > > >> > Hi Tomasz, > > >> > > > >> > On 10 May 2013 05:35, Tomasz Figa 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 > > >> >> > --- > > >> >> > > > >> >> > 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@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. Best regards, > Tomasz > > -- Thanks and Regards Vikas Sajjan --089e01494164311b4b04dc58c605 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
HI Tomasz,


On 10 May 2013 13:03, Tomasz Figa <<= a href=3D"mailto:tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" target=3D"_blank">tomasz.figa@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-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> > Hi Olof,
> >
> > On 10 May 2013 11:08, Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org> wrote:
> >> On Thu, May 9, 2013 at 7:55 PM, Vikas Sajjan
> >> <vikas.sajjan@l= inaro.org>
> >>
> >> wrote:
> >> > Hi Tomasz,
> >> >
> >> > On 10 May 2013 05:35, Tomasz Figa <tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> >> Hi Vikas,
> >> >>
> >> >> On Wednesday 08 of May 2013 11:31:34 Vikas Sajjan wr= ote:
> >> >> > Adds display timing node for a DP panel to Arnd= ale Board DTS
> >> >> > file
> >> >> >
> >> >> > Signed-off-by: Vikas Sajjan <vikas.sajjan-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> >> >> > ---
> >> >> >
> >> >> > =A0arch/arm/boot/dts/exynos5250-arndale.dts | = =A0 16
> >> >> > =A0++++++++++++++++
> >> >> > =A01 file changed, 16 insertions(+)
> >> >> >
> >> >> > diff --git a/arch/arm/boot/dts/exynos5250-arnda= le.dts
> >> >> > b/arch/arm/boot/dts/exynos5250-arndale.dts inde= x
> >> >> > f68b820..c831a5c
> >> >> > 100644
> >> >> > --- a/arch/arm/boot/dts/exynos5250-arndale.dts<= br> > >> >> > +++ b/arch/arm/boot/dts/exynos5250-arndale.dts<= br> > >> >> > @@ -459,4 +459,20 @@
> >> >> >
> >> >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 samsung,lane-count = =3D <4>;
> >> >> >
> >> >> > =A0 =A0 =A0 };
> >> >> >
> >> >> > + =A0 =A0 display-timings {
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 native-mode =3D <&= amp;timing0>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 timing0: timing@0 { > >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* 25= 60x1600 DP panel */
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 clock= -frequency =3D <50000>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 hacti= ve =3D <2560>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 vacti= ve =3D <1600>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 hfron= t-porch =3D <48>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 hback= -porch =3D <80>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 hsync= -len =3D <32>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 vback= -porch =3D <16>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 vfron= t-porch =3D <8>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 vsync= -len =3D <6>;
> >> >> > + =A0 =A0 =A0 =A0 =A0 =A0 };
> >> >> > + =A0 =A0 };
> >> >>
> >> >> 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" =A0as done in this = link
> >>
> >> https://git.kernel.org/cgit/linux/ke= rnel/git/daeinki/drm-exynos.git/c
> >> ommit/?h=3Dexynos-drm-next&id=3D7f4596f4aebcc9fcf2d50d3fe= 398508d710c4dd0
> >>
> >> That function passes in a device node pointer to the FIMD dev= ice
> >> 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<= br> > >> completely
> >> wrong.
> >>
> >> =A0 =A0 =A0 =A0 I referred this "
>
> Documentation/devicetree/bindings/video/display-timing.txt" for e= xample
>
> =A0 =A0 =A0 =A0 =A0 =A0 here it dosen't mention about whether disp= lay timings node
> can be placed at the root of the device tree or NOT.
> =A0Not 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 s= ay
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?

=A0 =A0 so what do you think, how=A0 should we modify= this patch so that it belongs to a specific video outputs.

Best regards,
Tomasz




--
Thanks and Regards
= =A0Vikas Sajjan
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