On Mon, Apr 14, 2014 at 12:21:44PM +0800, Zhao Yakui wrote:
> V1->V2: Follow Daniel's comment and use the simple ping-pong mechanism.
> This is only to add the support of dual BSD rings on BDW GT3 machine.
> The further optimization will be considered in another patch set.
>
> The BDW GT3 has two independent BSD rings, which can be used to process the
> video commands. To be simpler, it is transparent to user-space driver/middle.
> Instead the kernel driver will decide which ring is to dispatch the BSD video
> command.
>
> As every BSD ring is powerful, it is enough to dispatch the BSD video command
> based on the drm fd. In such case it can play back video stream while encoding
> another video stream. The coarse ping-pong mechanism is used to determine
> which BSD ring is used to dispatch the BSD video command.
>
> Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_dma.c | 3 +++
> drivers/gpu/drm/i915/i915_drv.h | 3 +++
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 37 +++++++++++++++++++++++++++-
> 3 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 0b38f88..4d27cf4 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1572,6 +1572,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
> spin_lock_init(&dev_priv->backlight_lock);
> spin_lock_init(&dev_priv->uncore.lock);
> spin_lock_init(&dev_priv->mm.object_stat_lock);
> + atomic_set(&dev_priv->bsd_cmd_counter, 0);
> mutex_init(&dev_priv->dpio_lock);
> mutex_init(&dev_priv->modeset_restore_lock);
>
> @@ -1929,6 +1930,8 @@ void i915_driver_postclose(struct drm_device *dev, struct drm_file *file)
> {
> struct drm_i915_file_private *file_priv = file->driver_priv;
>
> + if (file_priv && file_priv->bsd_ring)
> + file_priv->bsd_ring = NULL;
> kfree(file_priv);
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index ac5598c3..68e8166 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1466,6 +1466,8 @@ struct drm_i915_private {
> struct i915_dri1_state dri1;
> /* Old ums support infrastructure, same warning applies. */
> struct i915_ums_state ums;
> + /* the lock for dispatch video commands on two BSD rings */
> + atomic_t bsd_cmd_counter;
You're still using atomic_t for no real good reason.
gen8_dispatch_bsd_ring is always called with the dev->struct_mutex lock
held, so there's really no reason for it.
-Daniel
> };
>
> static inline struct drm_i915_private *to_i915(const struct drm_device *dev)
> @@ -1673,6 +1675,7 @@ struct drm_i915_file_private {
>
> struct i915_hw_context *private_default_ctx;
> atomic_t rps_wait_boost;
> + struct intel_ring_buffer *bsd_ring;
> };
>
> /*
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 341ec68..720ef17 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -999,6 +999,34 @@ i915_reset_gen7_sol_offsets(struct drm_device *dev,
> return 0;
> }
>
> +/**
> + * Find one BSD ring to dispatch the corresponding BSD command.
> + * The Ring ID is returned.
> + */
> +static int gen8_dispatch_bsd_ring(struct drm_device *dev,
> + struct drm_file *file)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct drm_i915_file_private *file_priv = file->driver_priv;
> +
> + /* Check whether the file_priv is using one ring */
> + if (file_priv->bsd_ring)
> + return file_priv->bsd_ring->id;
> + else {
> + /* If no, use the ping-pong mechanism to select one ring */
> + int counter, ring_id;
> + smp_mb__before_atomic_inc();
> + counter = atomic_inc_return(&dev_priv->bsd_cmd_counter);
> + if (counter % 2 == 0)
> + ring_id = VCS;
> + else
> + ring_id = VCS2;
> +
> + file_priv->bsd_ring = &dev_priv->ring[ring_id];
> + return ring_id;
> + }
> +}
> +
> static int
> i915_gem_do_execbuffer(struct drm_device *dev, void *data,
> struct drm_file *file,
> @@ -1043,7 +1071,14 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>
> if ((args->flags & I915_EXEC_RING_MASK) == I915_EXEC_DEFAULT)
> ring = &dev_priv->ring[RCS];
> - else
> + 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];
> + } else
> + ring = &dev_priv->ring[VCS];
> + } else
> ring = &dev_priv->ring[(args->flags & I915_EXEC_RING_MASK) - 1];
>
> if (!intel_ring_initialized(ring)) {
> --
> 1.7.10.1
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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