On Wed, Jul 30, 2014 at 11:54:00AM +0530, Ajay kumar wrote:
Hi Thierry,
On Tue, Jul 29, 2014 at 5:17 PM, Thierry Reding thierry.reding@gmail.com wrote:
On Tue, Jul 29, 2014 at 01:42:09PM +0200, Andreas Färber wrote:
Am 29.07.2014 13:36, schrieb Thierry Reding:
On Tue, Jul 29, 2014 at 01:21:48PM +0200, Andreas Färber wrote:
Hi Ajay,
Am 28.07.2014 08:13, schrieb Ajay kumar:
On 7/27/14, Andreas Färber afaerber@suse.de wrote: > Am 25.07.2014 21:22, schrieb Ajay Kumar: >> This series is based on exynos-drm-next branch of Inki Dae's tree at: >> git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos.git >> >> I have tested this after adding few DT changes for exynos5250-snow, >> exynos5420-peach-pit and exynos5800-peach-pi boards. > > I'm trying to test this with a modified exynos5250-spring DT
[...]
Unfortunately the most I got on Spring with attached DT was a blank screen with a white horizontal line in the middle.
Do I need to specify a specific panel model for Spring?
[...]
From 9172a26a8f0d0f0d170bd27e1c150ad204d8086a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andreas=20F=C3=A4rber?= afaerber@suse.de Date: Sun, 27 Jul 2014 21:58:06 +0200 Subject: [PATCH] ARM: dts: exynos5250: Add eDP/LVDS bridge to Spring MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
Signed-off-by: Ajay Kumar ajaykumar.rs@samsung.com [AF: Redone for v6] Signed-off-by: Andreas F??rber afaerber@suse.de
arch/arm/boot/dts/exynos5250-spring.dts | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/exynos5250-spring.dts b/arch/arm/boot/dts/exynos5250-spring.dts index 687dfab86bc8..517b1ff2bfdf 100644 --- a/arch/arm/boot/dts/exynos5250-spring.dts +++ b/arch/arm/boot/dts/exynos5250-spring.dts @@ -64,10 +64,14 @@ vdd_pll-supply = <&s5m_ldo8_reg>; };
- panel: panel {
compatible = "simple-panel";- };
You can't do this. "simple-panel" isn't a valid panel model. It should probably be removed from the platform_of_match table in the driver.
Okay, that means the Snow DT is wrong, too: https://patchwork.kernel.org/patch/4625441/
And the others specify it as fallback: https://patchwork.kernel.org/patch/4625461/ https://patchwork.kernel.org/patch/4625451/
A quick grep shows that many (all?) devices that use DRM panels provide simple-panel as fallback. That's probably fine as long as they also do provide the specific model. But given that simple-panel does not have a mode or physical size, I don't think even that makes sense.
On snow, the bridge chip provides the display mode instead of the panel. That is why display was working for me.
Okay, I suppose under some circumstances that might make sense. Although it's still always the panel that dictates the display timings, so the panel node needs to have a panel model specific compatible value with a matching entry in the panel-simple driver so that it can even be used in setups without a bridge.
One other thing: how does the bridge know which mode to drive? I suspect that it can drive more than one mode? Can it freely be configured or does it have a predefined set of modes? If the latter, then according to what you said above there needs to be a way to configure the bridge (via DT?) so that it reports the mode matching the panel. I wonder if that should be handled completely in code, so that for example a bridge has a panel attached it can use the panel's .get_modes() and select a matching mode among the set that it supports.
Thierry