[Intel-gfx] [PATCH 1/4] drm/i915: Trim struct_mutex usage for kms

[Maarten Lankhorst]

Op 15-06-17 om 10:25 schreef Chris Wilson:
> Reduce acquisition of struct_mutex to the critical regions that must
> hold it; for KMS, we need struct_mutex currently only for the purpose of
> pinning/unpinning the framebuffer's VMA into the global GTT. This allows
> us to avoid taking the struct_mutex when disabling the CRTC (i.e. NULL
> framebuffer objects) before a reset. (Not yet achieving the full goal of
> avoiding the strut_mutex nesting, but good enough to break the first
> half of the reset deadlock.)
>
> v2: Keep pages pinning inside struct_mutex for the moment.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 80 ++++++++++++++++--------------------
>  1 file changed, 36 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index f9bf0d508053..b254094c689c 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> <snip>
> -	if (!obj && !old_obj)
> -		return 0;
^This needs to be a bugfix commit on its own, since it harmonizes fence waiting with drm_atomic_helper_wait_for_fences.


>  	if (old_obj) {
>  		struct drm_crtc_state *crtc_state =
>  			drm_atomic_get_existing_crtc_state(new_state->state,
> @@ -13399,6 +13364,33 @@ intel_prepare_plane_fb(struct drm_plane *plane,
>  	if (!obj)
>  		return 0;
>  
> +	ret = mutex_lock_interruptible(&dev_priv->drm.struct_mutex);
> +	if (ret) {
> +		i915_gem_object_unpin_pages(obj);
Should be in patch 4?

Otherwise patches look ok. I can't comment on patch 3, but with comments fixed and assuming kms_cursor_legacy still works.. for patch 1, 2, 4:
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>