Re: [PATCH] drm/i915: Report the actual swizzling back to userspace

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Oct 24, 2014 at 12:11:11PM +0100, Chris Wilson wrote:
> Userspace cares about whether or not swizzling depends on the page
> address for its direct access into bound objects. Extend the get_tiling
> ioctl to report the physical swizzling value in addition to the logical
> swizzling value so that userspace can accurately determine when it is
> possible for manual detiling.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Akash Goel <akash.goel@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>

I wonder whether we should care really, since on gen5+ we know that they
agree. Pimp some igt (by skipping if needed) to convince me?
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_tiling.c | 1 +
>  include/uapi/drm/i915_drm.h            | 6 ++++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> index 3c073fb58730..b53ec941f17e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> @@ -446,6 +446,7 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
>  	}
>  
>  	/* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
> +	args->phys_swizzle_mode = args->swizzle_mode;
>  	if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
>  		args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
>  	if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 7615ae68e015..5ff86692e03e 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -934,6 +934,12 @@ struct drm_i915_gem_get_tiling {
>  	 * mmap mapping.
>  	 */
>  	__u32 swizzle_mode;
> +
> +	/**
> +	 * Returned address bit 6 swizzling required for CPU access through
> +	 * mmap mapping whilst bound.
> +	 */
> +	__u32 phys_swizzle_mode;
>  };
>  
>  struct drm_i915_gem_get_aperture {
> -- 
> 2.1.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch