linux-kernel - Re: [RFT PATCHv2] drm/exynos: Enable DP clock to fix display on Exynos5250 and other

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Message-ID: <5515ADB6.6050204@collabora.co.uk>
Date:	Fri, 27 Mar 2015 20:21:26 +0100
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Jingoo Han <jg1.han@...sung.com>,
	Inki Dae <inki.dae@...sung.com>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	Seung-Woo Kim <sw0312.kim@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	David Airlie <airlied@...ux.ie>, Kukjin Kim <kgene@...nel.org>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fbdev@...r.kernel.org
CC:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Andrzej Hajda <a.hajda@...sung.com>, stable@...r.kernel.org
Subject: Re: [RFT PATCHv2] drm/exynos: Enable DP clock to fix display on Exynos5250
 and other

Hello Krzysztof,

On 03/27/2015 05:08 PM, Krzysztof Kozlowski wrote:
> After adding display power domain for Exynos5250 in commit
> 2d2c9a8d0a4f ("ARM: dts: add display power domain for exynos5250") the
> display on Chromebook Snow and others stopped working after boot.
> 
> The reason for this suggested Andrzej Hajda: the DP clock was disabled.
> This clock is required by Display Port and is enabled by bootloader.
> However when FIMD driver probing was deferred, the display power domain
> was turned off. This effectively reset the value of DP clock enable
> register.
> 
> When exynos-dp is later probed, the clock is not enabled and display is
> not properly configured:
> 
> exynos-dp 145b0000.dp-controller: Timeout of video streamclk ok
> exynos-dp 145b0000.dp-controller: unable to config video
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Reported-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> Fixes: 2d2c9a8d0a4f ("ARM: dts: add display power domain for exynos5250")
> Cc: <stable@...r.kernel.org>
> 
> ---
> 
> This should fix issue reported by Javier [1][2].
>

I tested this patch and does indeed solves both issues I reported
The exynos-dp probe deferral does not make the display to not be
working and also disabling and enabling the display with:

with /sys/devices/platform/exynos-drm/graphics/fb0/blank works.

Thanks a lot for fixing this issue.

On an Exynos5250 Snow Chromebook:

Tested-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>

Best regards,
Javier
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