[U-Boot] [PATCH 2/2] RFC: exynos: Disable the display controller when starting Linux

[Ajay kumar]

+Simon Glass


On Thu, Oct 3, 2013 at 2:25 PM, Albert ARIBAUD <albert.u.boot at aribaud.net>wrote:

> Hi Ajay,
>
> On Thu, 03 Oct 2013 14:34:20 +0530, Ajay Kumar
> <ajaykumar.rs at samsung.com> wrote:
>
> > If the exynos display controller is still active when Linux starts,
> > then it will result in a kernel panic while FIMD sysmmu driver is
> > getting probed.
> > Calling exynos_fimd_lcd_disable() before jumping into kernel
> > disables the display controller by switching off the windows,
> > hence resolving the kernel panic which arises from sysmmu driver.
> >
> > Create an Exynos specific definition for the weak function
> > arch_cleanup_before_linux(), and then place the call to
> > exynos_fimd_lcd_disable() inside the overrided definition of
> > arch_cleanup_before_linux().
> >
> > Signed-off-by: Ajay Kumar <ajaykumar.rs at samsung.com>
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > ---
>
> Why should the fix to this situation be making U-Boot disable the
> display controller rather than making Linux able to cope with an
> already active display controller?
>
> Besides, fixing Linux would allow seamless booting displays, without an
> ugly off-on glitch.
>
> Amicalement,
> --
> Albert.
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