[PATCH] drm/i915/skl: WaIgnoreDDIAStrap is forever, always init DDI A

[PATCH] drm/i915/skl: WaIgnoreDDIAStrap is forever, always init DDI A

[Jani Nikula]

There is currently conflicting documentation on which steppings the
workaround is needed, up to C vs. forever. However there is post-C
stepping hardware that doesn't report port presence on DDI A, leading to
black screen on eDP. Assume the strap isn't connected, and try to enable
DDI A on these machines. (We'll still check the VBT for the info in DDI
init.)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 21aa745caed1..aa208a2cfafc 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13949,8 +13949,7 @@ static void intel_setup_outputs(struct drm_device *dev)
 		 */
 		found = I915_READ(DDI_BUF_CTL_A) & DDI_INIT_DISPLAY_DETECTED;
 		/* WaIgnoreDDIAStrap: skl */
-		if (found ||
-		    (IS_SKYLAKE(dev) && INTEL_REVID(dev) < SKL_REVID_D0))
+		if (found || IS_SKYLAKE(dev))
 			intel_ddi_init(dev, PORT_A);
 
 		/* DDI B, C and D detection is indicated by the SFUSE_STRAP
-- 
2.1.4

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Re: [PATCH] drm/i915/skl: WaIgnoreDDIAStrap is forever, always init DDI A

[Daniel Vetter]

On Fri, Aug 14, 2015 at 10:53:17AM +0300, Jani Nikula wrote:
> There is currently conflicting documentation on which steppings the
> workaround is needed, up to C vs. forever. However there is post-C
> stepping hardware that doesn't report port presence on DDI A, leading to
> black screen on eDP. Assume the strap isn't connected, and try to enable
> DDI A on these machines. (We'll still check the VBT for the info in DDI
> init.)
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Mika Westerberg <mika.westerberg@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_display.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 21aa745caed1..aa208a2cfafc 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -13949,8 +13949,7 @@ static void intel_setup_outputs(struct drm_device *dev)
>  		 */
>  		found = I915_READ(DDI_BUF_CTL_A) & DDI_INIT_DISPLAY_DETECTED;
>  		/* WaIgnoreDDIAStrap: skl */
> -		if (found ||
> -		    (IS_SKYLAKE(dev) && INTEL_REVID(dev) < SKL_REVID_D0))
> +		if (found || IS_SKYLAKE(dev))
>  			intel_ddi_init(dev, PORT_A);
>  
>  		/* DDI B, C and D detection is indicated by the SFUSE_STRAP
> -- 
> 2.1.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH] drm/i915/skl: WaIgnoreDDIAStrap is forever, always init DDI A

[shuang.he]

Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 7198
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
ILK                                  302/302              302/302
SNB                                  315/315              315/315
IVB                                  336/336              336/336
BYT                 -1              283/283              282/283
HSW                                  378/378              378/378
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*BYT  igt@gem_partial_pwrite_pread@reads-uncached      PASS(1)      FAIL(1)
Note: You need to pay more attention to line start with '*'
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