Re: [PATCH v4 6/8] drm/i915: Align dumb buffer stride to 4k to allow for gtt remapping

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, May 09, 2019 at 03:21:57PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Align dumb buffer stride to 4k if the fb will be big enough to
> require gtt remapping.
> 
> v2: Leave the stride alone for buffers that look to be for the cursor
> v3: Make it not a hack (Daniel)
> 
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Yeah I think this is a reasonable heuristics.

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

> ---
>  drivers/gpu/drm/i915/i915_gem.c      | 26 +++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/intel_display.c |  1 -
>  drivers/gpu/drm/i915/intel_display.h |  2 ++
>  3 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 4e474bcf4c22..7cafd5612f71 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -52,6 +52,7 @@
>  #include "i915_trace.h"
>  #include "i915_vgpu.h"
>  
> +#include "intel_display.h"
>  #include "intel_drv.h"
>  #include "intel_frontbuffer.h"
>  #include "intel_pm.h"
> @@ -560,8 +561,31 @@ i915_gem_dumb_create(struct drm_file *file,
>  		     struct drm_device *dev,
>  		     struct drm_mode_create_dumb *args)
>  {
> +	int cpp = DIV_ROUND_UP(args->bpp, 8);
> +	u32 format;
> +
> +	switch (cpp) {
> +	case 1:
> +		format = DRM_FORMAT_C8;
> +		break;
> +	case 2:
> +		format = DRM_FORMAT_RGB565;
> +		break;
> +	case 4:
> +		format = DRM_FORMAT_XRGB8888;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
>  	/* have to work out size/pitch and return them */
> -	args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
> +	args->pitch = ALIGN(args->width * cpp, 64);
> +
> +	/* align stride to page size so that we can remap */
> +	if (args->pitch > intel_plane_fb_max_stride(to_i915(dev), format,
> +						    DRM_FORMAT_MOD_LINEAR))
> +		args->pitch = ALIGN(args->pitch, 4096);
> +
>  	args->size = args->pitch * args->height;
>  	return i915_gem_create(file, to_i915(dev),
>  			       &args->size, &args->handle);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 94faac9e3666..fa317c40d548 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2498,7 +2498,6 @@ bool is_ccs_modifier(u64 modifier)
>  	       modifier == I915_FORMAT_MOD_Yf_TILED_CCS;
>  }
>  
> -static
>  u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,
>  			      u32 pixel_format, u64 modifier)
>  {
> diff --git a/drivers/gpu/drm/i915/intel_display.h b/drivers/gpu/drm/i915/intel_display.h
> index 500eec90928d..1e6533fbd061 100644
> --- a/drivers/gpu/drm/i915/intel_display.h
> +++ b/drivers/gpu/drm/i915/intel_display.h
> @@ -436,6 +436,8 @@ void intel_link_compute_m_n(u16 bpp, int nlanes,
>  			    bool constant_n);
>  bool is_ccs_modifier(u64 modifier);
>  void lpt_disable_clkout_dp(struct drm_i915_private *dev_priv);
> +u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,
> +			      u32 pixel_format, u64 modifier);
>  bool intel_plane_can_remap(const struct intel_plane_state *plane_state);
>  
>  #endif
> -- 
> 2.21.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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