[Intel-gfx] [PATCH 1/2] drm/i915: Specify bsd rings through exec flag

[Daniel Vetter]

On Tue, Jan 13, 2015 at 08:48:24AM +0800, Zhipeng Gong wrote:
> On Skylake GT3 we have 2 Video Command Streamers (VCS), which is asymmetrical.
> For example, HEVC GPU commands can be only dispatched to VCS1 ring.
> But userspace has no control when using VCS1 or VCS2. This patch introduces
> a mechanism to avoid the default ping-pong mode and use one specific ring
> through execution flag. This mechanism is usable for all the platforms
> with 2 VCS rings.
>
> The open source usage is from these two commits in vaapi/intel:
> commit 702050f04131a44ef8ac16651708ce8a8d98e4b8
> Author: Zhao, Yakui <yakui.zhao at intel.com>
> Date:   Mon Nov 17 12:44:19 2014 +0800
>
>    Allow the batchbuffer to be submitted with override flag
>
> commit a56efcdf27d11ad9b21664b4a2cda72d7f90f5a8
> Author: Zhao Yakui <yakui.zhao at intel.com>
> Date:   Mon Nov 17 12:44:22 2014 +0800
>
>    Add the override flag to assure that HEVC video command
> always uses BSD ring0 for SKL GT3 machine
>
> v2: fix whitespace (Rodrigo)
> v3: remove incorrect chunk that came on -collector rebase. (Rodrigo)
> v4: change the comment (Zhipeng)
> v5: address Daniel's comment (Zhipeng)

Can you please be more specific here for the in-patch changelog? The idea
is that people understand the changes with just this, as-is you need to
dig out the old review thread (which is pretty much impossible).

I'll add that to the commit message when merging, so no need to
resend. I'll merge as soon as Rodrigo has doublechecked the revised
patches.
-Daniel

>
> Signed-off-by: Zhipeng Gong <zhipeng.gong at intel.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com> (for v4)
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 26 ++++++++++++++++++++++++--
>  include/uapi/drm/i915_drm.h                |  8 +++++++-
>  2 files changed, 31 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index e3ef177..b773368 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1380,13 +1380,35 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>   return -EINVAL;
>   }
>
> + if (((args->flags & I915_EXEC_RING_MASK) != I915_EXEC_BSD) &&
> +    ((args->flags & I915_EXEC_BSD_MASK) != 0)) {
> + DRM_DEBUG("execbuf with non bsd ring but with invalid "
> + "bsd dispatch flags: %d\n", (int)(args->flags));
> + return -EINVAL;
> + }
> +
>   if ((args->flags & I915_EXEC_RING_MASK) == I915_EXEC_DEFAULT)
>   ring = &dev_priv->ring[RCS];
>   else if ((args->flags & I915_EXEC_RING_MASK) == I915_EXEC_BSD) {
>   if (HAS_BSD2(dev)) {
>   int ring_id;
> - ring_id = gen8_dispatch_bsd_ring(dev, file);
> - ring = &dev_priv->ring[ring_id];
> +
> + switch (args->flags & I915_EXEC_BSD_MASK) {
> + case I915_EXEC_BSD_DEFAULT:
> + ring_id = gen8_dispatch_bsd_ring(dev, file);
> + ring = &dev_priv->ring[ring_id];
> + break;
> + case I915_EXEC_BSD_RING1:
> + ring = &dev_priv->ring[VCS];
> + break;
> + case I915_EXEC_BSD_RING2:
> + ring = &dev_priv->ring[VCS2];
> + break;
> + default:
> + DRM_DEBUG("execbuf with unknown bsd ring: %d\n",
> +  (int)(args->flags & I915_EXEC_BSD_MASK));
> + return -EINVAL;
> + }
>   } else
>   ring = &dev_priv->ring[VCS];
>   } else
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 2e559f6e..dc84561 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -750,7 +750,13 @@ struct drm_i915_gem_execbuffer2 {
>   */
>  #define I915_EXEC_HANDLE_LUT (1<<12)
>
> -#define __I915_EXEC_UNKNOWN_FLAGS -(I915_EXEC_HANDLE_LUT<<1)
> +/** Used for switching BSD rings on the platforms with two BSD rings */
> +#define I915_EXEC_BSD_MASK (3<<13)
> +#define I915_EXEC_BSD_DEFAULT (0<<13) /* default ping-pong mode */
> +#define I915_EXEC_BSD_RING1 (1<<13)
> +#define I915_EXEC_BSD_RING2 (2<<13)
> +
> +#define __I915_EXEC_UNKNOWN_FLAGS -(1<<15)
>
>  #define I915_EXEC_CONTEXT_ID_MASK (0xffffffff)
>  #define i915_execbuffer2_set_context_id(eb2, context) \
> --
> 1.8.3.1
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch