[Intel-gfx] [PATCH] drm/i915: Don't compare has_drrs strictly in pipe config

[Daniel Vetter]

On Wed, Nov 25, 2015 at 03:26:47PM +0100, Takashi Iwai wrote:
> The commit [cfb23ed622d0: drm/i915: Allow fuzzy matching in
> pipe_config_compare, v2] relaxed the way to compare the pipe
> configurations, but one new comparison sneaked in there: it added the
> strict has_drrs value check.  This causes a regression on many
> machines, typically HP laptops with a docking port, where the kernel
> spews warnings and eventually fails to set the mode properly like:
>  [drm:intel_pipe_config_compare [i915]] *ERROR* mismatch in has_drrs (expected 1, found 0)
>  ------------[ cut here ]------------
>  WARNING: CPU: 0 PID: 79 at drivers/gpu/drm/i915/intel_display.c:12700 intel_modeset_check_state+0x5aa/0x870 [i915]()
>  pipe state doesn't match!
>  ....
> 
> This patch just removes the check again for fixing the regression.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=104041
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92456
> Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=956397
> Fixes: cfb23ed622d0 ('drm/i915: Allow fuzzy matching in pipe_config_compare, v2')
> Cc: <stable at vger.kernel.org> # v4.3+
> Reported-and-tested-by: Max Lin <mlin at suse.com>
> Signed-off-by: Takashi Iwai <tiwai at suse.de>

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 71860f8680f9..12a2e9d1f633 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12460,7 +12460,6 @@ intel_pipe_config_compare(struct drm_device *dev,
>  	if (INTEL_INFO(dev)->gen < 8) {
>  		PIPE_CONF_CHECK_M_N(dp_m_n);
>  
> -		PIPE_CONF_CHECK_I(has_drrs);
>  		if (current_config->has_drrs)
>  			PIPE_CONF_CHECK_M_N(dp_m2_n2);
>  	} else
> -- 
> 2.6.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch