drm/vblank: add dynamic per-crtc vblank configuration support

We would like to be able to enable vblank_disable_immediate
unconditionally, however there are a handful of cases where a small off
delay is necessary (e.g. with PSR enabled). So, we would like to be able
to adjust the vblank off delay and disable imminent values dynamically
for a given CRTC. Since, it will allow drivers to apply static screen
optimizations more quickly and consequently allow users to benefit more
so from the power savings afforded by the aforementioned optimizations,
while avoiding issues in cases where an off delay is still warranted.
In particular, the PSR case requires a small off delay of 2 frames,
otherwise display firmware isn't able to keep up with all of the
requests made to amdgpu. So, introduce drm_crtc_vblank_on_config() which
is like drm_crtc_vblank_on(), but it allows drivers to specify the
vblank CRTC configuration before enabling vblanking support for a given
CRTC.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240725205109.209743-1-hamza.mahfooz@amd.com

2 files changed, 38 insertions, 4 deletions

diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 63767cf24371..c91f87b5242d 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -213,8 +213,9 @@ struct drm_device {
 	 * This can be set to true it the hardware has a working vblank counter
 	 * with high-precision timestamping (otherwise there are races) and the
 	 * driver uses drm_crtc_vblank_on() and drm_crtc_vblank_off()
-	 * appropriately. See also @max_vblank_count and
-	 * &drm_crtc_funcs.get_vblank_counter.
+	 * appropriately. Also, see @max_vblank_count,
+	 * &drm_crtc_funcs.get_vblank_counter and
+	 * &drm_vblank_crtc_config.disable_immediate.
 	 */
 	bool vblank_disable_immediate;
 
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index c8f829b4307c..151ab1e85b1b 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -79,6 +79,31 @@ struct drm_pending_vblank_event {
 };
 
 /**
+ * struct drm_vblank_crtc_config - vblank configuration for a CRTC
+ */
+struct drm_vblank_crtc_config {
+	/**
+	 * @offdelay_ms: Vblank off delay in ms, used to determine how long
+	 * &drm_vblank_crtc.disable_timer waits before disabling.
+	 *
+	 * Defaults to the value of drm_vblank_offdelay in drm_crtc_vblank_on().
+	 */
+	int offdelay_ms;
+
+	/**
+	 * @disable_immediate: See &drm_device.vblank_disable_immediate
+	 * for the exact semantics of immediate vblank disabling.
+	 *
+	 * Additionally, this tracks the disable immediate value per crtc, just
+	 * in case it needs to differ from the default value for a given device.
+	 *
+	 * Defaults to the value of &drm_device.vblank_disable_immediate in
+	 * drm_crtc_vblank_on().
+	 */
+	bool disable_immediate;
+};
+
+/**
  * struct drm_vblank_crtc - vblank tracking for a CRTC
  *
  * This structure tracks the vblank state for one CRTC.
@@ -99,8 +124,8 @@ struct drm_vblank_crtc {
 	wait_queue_head_t queue;
 	/**
 	 * @disable_timer: Disable timer for the delayed vblank disabling
-	 * hysteresis logic. Vblank disabling is controlled through the
-	 * drm_vblank_offdelay module option and the setting of the
+	 * hysteresis logic. Vblank disabling is controlled through
+	 * &drm_vblank_crtc_config.offdelay_ms and the setting of the
 	 * &drm_device.max_vblank_count value.
 	 */
 	struct timer_list disable_timer;
@@ -199,6 +224,12 @@ struct drm_vblank_crtc {
 	struct drm_display_mode hwmode;
 
 	/**
+	 * @config: Stores vblank configuration values for a given CRTC.
+	 * Also, see drm_crtc_vblank_on_config().
+	 */
+	struct drm_vblank_crtc_config config;
+
+	/**
 	 * @enabled: Tracks the enabling state of the corresponding &drm_crtc to
 	 * avoid double-disabling and hence corrupting saved state. Needed by
 	 * drivers not using atomic KMS, since those might go through their CRTC
@@ -247,6 +278,8 @@ void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe);
 void drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
 void drm_crtc_vblank_off(struct drm_crtc *crtc);
 void drm_crtc_vblank_reset(struct drm_crtc *crtc);
+void drm_crtc_vblank_on_config(struct drm_crtc *crtc,
+			       const struct drm_vblank_crtc_config *config);
 void drm_crtc_vblank_on(struct drm_crtc *crtc);
 u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc);
 void drm_crtc_vblank_restore(struct drm_crtc *crtc);