[Intel-gfx] [PATCH v2] drm/i915/icl: Fix CRC mismatch error for DP link layer compliance

[Kahola, Mika]

The patch looks ok to me.

On Wed, 2019-03-06 at 18:14 -0800, Aditya Swarup wrote:
> Setting the pixel rounding bit to 1 in PIPE_CHICKEN register allows
> to passthrough FB pixels unmodified across pipe. This fixes the
> failures
> for DP link layer compliance tests 4.4.1.1, 4.4.1.2 & 4.4.1.3.
> (Lineage #1605353570)
> 
> v2: This is also needed to fix failing IGT test case kms_cursor_crc
> on
> ICL.(Mika Kahola)
> Make macros consistent with i915_reg.h comments.(Jani Nikula)
> 
> Cc: Clint Taylor <clinton.a.taylor at intel.com>
> Cc: Mika Kahola <mika.kahola at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>

Reviewed-by: Mika Kahola <mika.kahola at intel.com>

> Signed-off-by: Aditya Swarup <aditya.swarup at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h      | 13 +++++++------
>  drivers/gpu/drm/i915/intel_display.c |  8 +++++++-
>  2 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index c9b868347481..cf15a9a97d74 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7659,12 +7659,13 @@ enum {
>  #define  GEN9_LBS_SLA_RETRY_TIMER_DECREMENT_ENABLE	(1 << 2)
>  
>  /*GEN11 chicken */
> -#define _PIPEA_CHICKEN			0x70038
> -#define _PIPEB_CHICKEN			0x71038
> -#define _PIPEC_CHICKEN			0x72038
> -#define  PER_PIXEL_ALPHA_BYPASS_EN	(1 << 7)
> -#define PIPE_CHICKEN(pipe)		_MMIO_PIPE(pipe,
> _PIPEA_CHICKEN,\
> -						   _PIPEB_CHICKEN)
> +#define _PIPEA_CHICKEN				0x70038
> +#define _PIPEB_CHICKEN				0x71038
> +#define _PIPEC_CHICKEN				0x72038
> +#define PIPE_CHICKEN(pipe)			_MMIO_PIPE(pipe,
> _PIPEA_CHICKEN,\
> +							   _PIPEB_CHICK
> EN)
> +#define   PIXEL_ROUNDING_TRUNC_FB_PASSTHRU 	(1 << 15)
> +#define   PER_PIXEL_ALPHA_BYPASS_EN		(1 << 7)
>  
>  /* PCH */
>  
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index d852cb282060..92be3476fef1 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3970,7 +3970,13 @@ static void icl_set_pipe_chicken(struct
> intel_crtc *crtc)
>  	 * and rounding for per-pixel values 00 and 0xff
>  	 */
>  	tmp |= PER_PIXEL_ALPHA_BYPASS_EN;
> -
> +	/*
> +	 * Display WA # 1605353570: icl
> +	 * Set the pixel rounding bit to 1 for allowing
> +	 * passthrough of Frame buffer pixels unmodified
> +	 * across pipe
> +	 */
> +	tmp |= PIXEL_ROUNDING_TRUNC_FB_PASSTHRU;
>  	I915_WRITE(PIPE_CHICKEN(pipe), tmp);
>  }
>