Re: [PATCH 1/1] Revert "ARM: dts: add display power domain for exynos5250"

From: Kevin Hilman
Date: Wed Apr 29 2015 - 13:40:18 EST

Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx> writes:

> This reverts commit 2d2c9a8d0a4f90e298315d2f4a282d8bd5d45e5c
> ("ARM: dts: add display power domain for exynos5250").
> The mentioned commit added a domain definition for the DISP1
> power domain and references to it in the appropriate devices
> but this change breaks the display in at least the Exynos5250
> based Snow and Spring Chromebooks.
> On these machines, the boot-loader enables the DISP1 domain and
> before the mentioned commit, the kernel didn't know about it so
> the power domain remained always enabled.
> But after that commit when the exynos-dp probe is deferred,
> the DISP1 domain is powered off and on again but the exynos-dp
> driver fails to configure the video showing the following error:
> exynos-dp 145b0000.dp-controller: Timeout of video streamclk ok
> exynos-dp 145b0000.dp-controller: unable to config video
> The same issue happens when the display is turned off and on
> again using DPMS.
> So, it seems the DISP1 power domain definition is not complete
> since the display works with the initialization made by the boot
> loader but it does not work when the power domain is enabled by
> the kernel.
> Having the definition in the DTS makes the power domain to be
> powered on when needed and powered off when not needed which is
> better in terms of power consumption but for now is safer to just
> revert the commit to avoid adding a regression in some machines.
> Signed-off-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>

Tested-by: Kevin Hilman <khilman@xxxxxxxxxx>

FWIW, this patch fixes the boot panics when using MMC rootfs on
exynos5800-peach-pi with current linux-next that have been happening
for awhile.

For several months now, DRM/display related stuff is very routinely
breaking basic booting on exynos5, which gives the rather strong
impression that the DRM stuff is not tested well enough to be merged.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at