On Thu, Mar 09, 2017 at 05:44:34PM +0200, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Use I915_{READ,WRITE}_FW() for updating the DSPARB registers on
> VLV/CHV. This is less expesive as we can grab the uncore.lock across
> the entire sequence of reads and writes instead of each register
> access grabbing it.
>
> This also allows us to eliminate the dsparb lock entirely as the
> uncore.lock now effectively protects the contents of the DSPARB
> registers.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 1 -
> drivers/gpu/drm/i915/i915_drv.h | 3 ---
> drivers/gpu/drm/i915/intel_pm.c | 36 +++++++++++++++++++++---------------
> 3 files changed, 21 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index b1e9027a4f80..debb74a2b2a9 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -827,7 +827,6 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
>
> spin_lock_init(&dev_priv->mm.object_stat_lock);
> spin_lock_init(&dev_priv->mmio_flip_lock);
> - spin_lock_init(&dev_priv->wm.dsparb_lock);
> mutex_init(&dev_priv->sb_lock);
> mutex_init(&dev_priv->modeset_restore_lock);
> mutex_init(&dev_priv->av_mutex);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3002996ddbed..6af0b1d33cab 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2375,9 +2375,6 @@ struct drm_i915_private {
> } sagv_status;
>
> struct {
> - /* protects DSPARB registers on pre-g4x/vlv/chv */
> - spinlock_t dsparb_lock;
> -
> /*
> * Raw watermark latency values:
> * in 0.1us units for WM0,
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 99e09f63d4b3..24cdc13a416a 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -1358,13 +1358,19 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
>
> trace_vlv_fifo_size(crtc, sprite0_start, sprite1_start, fifo_size);
>
> - spin_lock(&dev_priv->wm.dsparb_lock);
> + /*
> + * uncore.lock serves a double purpose here. It allows us to
> + * use the less expensive I915_{READ,WRITE}_FW() functions, and
> + * it protects the DSPARB registers from getting clobbered by
> + * parallel updates from multiple pipes.
> + */
> + spin_lock(&dev_priv->uncore.lock);
Might be nice to document that the irq is disabled by
intel_pipe_update_start() (hence why spin_lock is safe).
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
