Re: [PATCH v6] drm/i915: Fix FBC cfb stride programming for non X-tiled FB

[Paulo Zanoni <paulo.r.zanoni@intel.com>]

Em Sex, 2017-08-11 às 00:00 +0530, Praveen Paneri escreveu:
> When FBC is enabled for linear, legacy Y-tiled and Yf-tiled
> surfaces on gen9, the cfb stride must be programmed by SW as
> 
> cfb_stride = ceiling[(at least plane width in pixels)/
> 		     (32 * compression limit factor)] * 8
> 
> v2: Minor fix for a build error
> v3: Fixed subject, register name and platform check (Ville)
> v4: Added WA details in comment (Paulo)
> v5:
>  - Read modified reg write to preserve other bit values (Paulo)
>  - Store modified stride value in reg_params (Paulo)
>  - Keep GLK out of the WA (Paulo)
> v6:
>  - added additional field in reg_params for gen9_wa_cfb_stride
> (Paulo)
>  - Used appropriate bit mask while writing the register (Paulo)
> 
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Signed-off-by: Praveen Paneri <praveen.paneri@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h  |  1 +
>  drivers/gpu/drm/i915/i915_reg.h  |  4 ++++
>  drivers/gpu/drm/i915/intel_fbc.c | 27 +++++++++++++++++++++++++++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h
> index 907603c..1d40a7c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1106,6 +1106,7 @@ struct intel_fbc {
>  		} fb;
>  
>  		int cfb_size;
> +		unsigned int gen9_wa_cfb_stride;
>  	} params;
>  
>  	struct intel_fbc_work {
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index 56df86e..51cab2f 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6801,6 +6801,10 @@ enum {
>  #define  GLK_CL1_PWR_DOWN	(1 << 11)
>  #define  GLK_CL0_PWR_DOWN	(1 << 10)
>  
> +#define CHICKEN_MISC_4		_MMIO(0x4208c)
> +#define   FBC_STRIDE_OVERRIDE	(1<<13)

See the new comment at the top of this file. (1 << 13) is preferred.


> +#define   FBC_STRIDE_MASK	0x1FFF
> +
>  #define _CHICKEN_PIPESL_1_A	0x420b0
>  #define _CHICKEN_PIPESL_1_B	0x420b4
>  #define  HSW_FBCQ_DIS			(1 << 22)
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c
> b/drivers/gpu/drm/i915/intel_fbc.c
> index 860b8c2..21f6b33 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -291,6 +291,21 @@ static void gen7_fbc_activate(struct
> drm_i915_private *dev_priv)
>  	u32 dpfc_ctl;
>  	int threshold = dev_priv->fbc.threshold;
>  
> +	/* Display WA #0529: skl, kbl, bxt but not for glk*/

Don't need to list excluded platforms. Also, missing space before the
asterisk.


> +	if (IS_GEN9(dev_priv) && !IS_GEMINILAKE(dev_priv)) {
> +		u32 chicken_misc4 = I915_READ(CHICKEN_MISC_4);

In our driver, variables with the name of register usually contain its
address. We generally use "val" for values.


> +
> +		if (i915_gem_object_get_tiling(params->vma->obj)
> +				!= I915_TILING_X) {
> +                       I915_WRITE(CHICKEN_MISC_4, chicken_misc4 |
> +                               FBC_STRIDE_OVERRIDE |
> +                               (params->gen9_wa_cfb_stride &
> FBC_STRIDE_MASK));

We're not masking the old value before overwriting it, eventually
everything is going to be 0xFFF if we keep changing the stride without
disabling it.


> +		} else {
> +			I915_WRITE(CHICKEN_MISC_4, chicken_misc4 &
> +				~(FBC_STRIDE_OVERRIDE |
> FBC_STRIDE_MASK));
> +		}
> +	}
> +

Major issue with spaces instead of tabs in the whole chunk above.


>  	dpfc_ctl = 0;
>  	if (IS_IVYBRIDGE(dev_priv))
>  		dpfc_ctl |= IVB_DPFC_CTL_PLANE(params->crtc.plane);
> @@ -865,6 +880,7 @@ static void intel_fbc_get_reg_params(struct
> intel_crtc *crtc,
>  	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>  	struct intel_fbc *fbc = &dev_priv->fbc;
>  	struct intel_fbc_state_cache *cache = &fbc->state_cache;
> +	int threshold = dev_priv->fbc.threshold;
>  
>  	/* Since all our fields are integer types, use memset here
> so the
>  	 * comparison function can rely on memcmp because the
> padding will be
> @@ -880,6 +896,17 @@ static void intel_fbc_get_reg_params(struct
> intel_crtc *crtc,
>  	params->fb.format = cache->fb.format;
>  	params->fb.stride = cache->fb.stride;
>  
> +	/* Display WA #0529: skl, kbl, bxt but not for glk*/
> +	if (IS_GEN9(dev_priv) && !IS_GEMINILAKE(dev_priv)) {
> +		/* calculate cfb stride for y-tiled mode */
> +		if (i915_gem_object_get_tiling(params->vma->obj)
> +				!= I915_TILING_X) {

We don't need the check here, it's already done in the other part of
the code.

Anyway, to save time on yet another iteration of this patch I went
ahead and fixed the styling issues and the masking problem and merged
the patch. Thanks for the patch!

> +			int cfb_stride = DIV_ROUND_UP(cache-
> >plane.src_w,
> +					(32 * threshold)) * 8;
> +			params->gen9_wa_cfb_stride = cfb_stride;
> +		}
> +	}
> +
>  	params->cfb_size = intel_fbc_calculate_cfb_size(dev_priv,
> cache);
>  }
>  
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