System76 - Intel DRM patch

[Robert Hooker]

On Sun, Apr 1, 2012 at 5:55 PM, Carl Richell <carl at system76.com> wrote:
> Hi,
>
> We'd like to make sure 12.04 is flawless on our next-gen laptops. A kernel
> patch is required to fix an offset desktop bug. The patch applies cleanly on
> the current precise kernel. Please see:
>
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/968307
>
> https://bugzilla.kernel.org/show_bug.cgi?id=43012
>
>
> -- Carl
>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=47271
> Signed-off-by: Chris Wilson<chris at chris-wilson.co.uk>
> Cc: stable at kernel.org
> ---
>  drivers/gpu/drm/i915/i915_reg.h      |    1 +
>  drivers/gpu/drm/i915/intel_display.c |    6 ++++++
>  2 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index 3d9ba01..218b3db9 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -2385,6 +2385,7 @@
>  #define   PIPECONF_DISABLE     0
>  #define   PIPECONF_DOUBLE_WIDE (1<<30)
>  #define   I965_PIPECONF_ACTIVE (1<<30)
> +#define   PIPECONF_FRAME_START_DELAY_MASK (3<<27)
>  #define   PIPECONF_SINGLE_WIDE 0
>  #define   PIPECONF_PIPE_UNLOCKED 0
>  #define   PIPECONF_PIPE_LOCKED (1<<25)
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 6b0562b..73ea6e9 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7695,6 +7695,12 @@ static void intel_sanitize_modesetting(struct
> drm_device *dev,
>        struct drm_i915_private *dev_priv = dev->dev_private;
>        u32 reg, val;
>
> +       /* Clear any frame start delays used for debugging left by the BIOS
> */
> +       for_each_pipe(pipe) {
> +               reg = PIPECONF(pipe);
> +               I915_WRITE(reg, I915_READ(reg)&
>  ~PIPECONF_FRAME_START_DELAY_MASK);
> +       }
> +
>        if (HAS_PCH_SPLIT(dev))
>                return;
>
>
>
> --
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

This even hit some machines we at Canonical have in the past few days
and I was going to propose this as well. Note: It's specific to
machines with v2132 vbios versions, and will very likely be fixed in a
later vbios but it's pretty safe to say this vbios may ship in some
early panther point machines and causes screen corruption such as
http://ubuntuone.com/69BR1liJd25E6DRNqytGJF on boot so it would be
good to have in time to make the livecd's kernel. The original commit
message that will go upstream is here
http://lists.freedesktop.org/archives/intel-gfx/2012-March/015696.html
which also had

Reported-and-tested-by: Carl Richell <carl at system76.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43012

added in http://lists.freedesktop.org/archives/intel-gfx/2012-March/016097.html

Acked-by: Robert Hooker <sarvatt at canonical.com>