On Wed, Sep 18, 2019 at 04:07:29PM -0400, Sean Paul wrote: > From: Sean Paul <[email protected]> > > Currently the self refresh idle timer is a const set by the crtc. This > is fine if the self refresh entry/exit times are well-known for all > panels used on that crtc. However panels and workloads can vary quite a > bit, and a timeout which works well for one doesn't work well for > another. > > In the extreme, if the timeout is too short we could get in a situation > where the self refresh exits are taking so long we queue up a self refresh > entry before the exit commit is even finished. > > This patch changes the idle timeout to a moving average of the entry > times + a moving average of exit times + the crtc constant. > > This patch was tested on rockchip, with a kevin CrOS panel the idle > delay averages out to about ~235ms (35 entry + 100 exit + 100 const). On > the same board, the bob panel idle delay lands around ~340ms (90 entry > + 150 exit + 100 const). > > WRT the dedicated mutex in self_refresh_data, it would be nice if we > could rely on drm_crtc.mutex to protect the average times, but there are > a few reasons why a separate lock is a better choice: > - We can't rely on drm_crtc.mutex being held if we're doing a nonblocking > commit > - We can't grab drm_crtc.mutex since drm_modeset_lock() doesn't tell us > whether the lock was already held in the acquire context (it eats > -EALREADY), so we can't tell if we should drop it or not > - We don't need such a heavy-handed lock for what we're trying to do, > commit ordering doesn't matter, so a point-of-use lock will be less > contentious > > Reviewed-by: Daniel Vetter <[email protected]>
Pushed the first 2 to drm-misc-next-fixes to fix the gru-bob regression. I'll fix up the 3rd patch separately. Thank you for the reviews! Sean > Signed-off-by: Sean Paul <[email protected]> > Link to v1: > https://patchwork.freedesktop.org/patch/msgid/[email protected] > > Changes in v2: > - Migrate locking explanation from comment to commit msg (Daniel) > - Turf constant entry delay and multiply the avg times by 2 (Daniel) > --- > drivers/gpu/drm/drm_atomic_helper.c | 20 ++++++ > drivers/gpu/drm/drm_self_refresh_helper.c | 72 +++++++++++++++++++-- > drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 5 +- > include/drm/drm_self_refresh_helper.h | 6 +- > 4 files changed, 90 insertions(+), 13 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c > b/drivers/gpu/drm/drm_atomic_helper.c > index 9d7e4da6c292..3f13fa9a9e24 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -26,6 +26,7 @@ > */ > > #include <linux/dma-fence.h> > +#include <linux/ktime.h> > > #include <drm/drm_atomic.h> > #include <drm/drm_atomic_helper.h> > @@ -1570,9 +1571,23 @@ static void commit_tail(struct drm_atomic_state > *old_state) > { > struct drm_device *dev = old_state->dev; > const struct drm_mode_config_helper_funcs *funcs; > + ktime_t start; > + s64 commit_time_ms; > > funcs = dev->mode_config.helper_private; > > + /* > + * We're measuring the _entire_ commit, so the time will vary depending > + * on how many fences and objects are involved. For the purposes of self > + * refresh, this is desirable since it'll give us an idea of how > + * congested things are. This will inform our decision on how often we > + * should enter self refresh after idle. > + * > + * These times will be averaged out in the self refresh helpers to avoid > + * overreacting over one outlier frame > + */ > + start = ktime_get(); > + > drm_atomic_helper_wait_for_fences(dev, old_state, false); > > drm_atomic_helper_wait_for_dependencies(old_state); > @@ -1582,6 +1597,11 @@ static void commit_tail(struct drm_atomic_state > *old_state) > else > drm_atomic_helper_commit_tail(old_state); > > + commit_time_ms = ktime_ms_delta(ktime_get(), start); > + if (commit_time_ms > 0) > + drm_self_refresh_helper_update_avg_times(old_state, > + (unsigned long)commit_time_ms); > + > drm_atomic_helper_commit_cleanup_done(old_state); > > drm_atomic_state_put(old_state); > diff --git a/drivers/gpu/drm/drm_self_refresh_helper.c > b/drivers/gpu/drm/drm_self_refresh_helper.c > index 9095cebf2147..68f4765a5896 100644 > --- a/drivers/gpu/drm/drm_self_refresh_helper.c > +++ b/drivers/gpu/drm/drm_self_refresh_helper.c > @@ -5,6 +5,7 @@ > * Authors: > * Sean Paul <[email protected]> > */ > +#include <linux/average.h> > #include <linux/bitops.h> > #include <linux/slab.h> > #include <linux/workqueue.h> > @@ -50,10 +51,17 @@ > * atomic_check when &drm_crtc_state.self_refresh_active is true. > */ > > +#define SELF_REFRESH_AVG_SEED_MS 200 > + > +DECLARE_EWMA(psr_time, 4, 4) > + > struct drm_self_refresh_data { > struct drm_crtc *crtc; > struct delayed_work entry_work; > - unsigned int entry_delay_ms; > + > + struct mutex avg_mutex; > + struct ewma_psr_time entry_avg_ms; > + struct ewma_psr_time exit_avg_ms; > }; > > static void drm_self_refresh_helper_entry_work(struct work_struct *work) > @@ -121,6 +129,44 @@ static void drm_self_refresh_helper_entry_work(struct > work_struct *work) > drm_modeset_acquire_fini(&ctx); > } > > +/** > + * drm_self_refresh_helper_update_avg_times - Updates a crtc's SR time > averages > + * @state: the state which has just been applied to hardware > + * @commit_time_ms: the amount of time in ms that this commit took to > complete > + * > + * Called after &drm_mode_config_funcs.atomic_commit_tail, this function will > + * update the average entry/exit self refresh times on self refresh > transitions. > + * These averages will be used when calculating how long to delay before > + * entering self refresh mode after activity. > + */ > +void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state, > + unsigned int commit_time_ms) > +{ > + struct drm_crtc *crtc; > + struct drm_crtc_state *old_crtc_state, *new_crtc_state; > + int i; > + > + for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, > + new_crtc_state, i) { > + struct drm_self_refresh_data *sr_data = crtc->self_refresh_data; > + struct ewma_psr_time *time; > + > + if (old_crtc_state->self_refresh_active == > + new_crtc_state->self_refresh_active) > + continue; > + > + if (new_crtc_state->self_refresh_active) > + time = &sr_data->entry_avg_ms; > + else > + time = &sr_data->exit_avg_ms; > + > + mutex_lock(&sr_data->avg_mutex); > + ewma_psr_time_add(time, commit_time_ms); > + mutex_unlock(&sr_data->avg_mutex); > + } > +} > +EXPORT_SYMBOL(drm_self_refresh_helper_update_avg_times); > + > /** > * drm_self_refresh_helper_alter_state - Alters the atomic state for SR exit > * @state: the state currently being checked > @@ -152,6 +198,7 @@ void drm_self_refresh_helper_alter_state(struct > drm_atomic_state *state) > > for_each_new_crtc_in_state(state, crtc, crtc_state, i) { > struct drm_self_refresh_data *sr_data; > + unsigned int delay; > > /* Don't trigger the entry timer when we're already in SR */ > if (crtc_state->self_refresh_active) > @@ -161,8 +208,13 @@ void drm_self_refresh_helper_alter_state(struct > drm_atomic_state *state) > if (!sr_data) > continue; > > + mutex_lock(&sr_data->avg_mutex); > + delay = (ewma_psr_time_read(&sr_data->entry_avg_ms) + > + ewma_psr_time_read(&sr_data->exit_avg_ms)) * 2; > + mutex_unlock(&sr_data->avg_mutex); > + > mod_delayed_work(system_wq, &sr_data->entry_work, > - msecs_to_jiffies(sr_data->entry_delay_ms)); > + msecs_to_jiffies(delay)); > } > } > EXPORT_SYMBOL(drm_self_refresh_helper_alter_state); > @@ -170,12 +222,10 @@ EXPORT_SYMBOL(drm_self_refresh_helper_alter_state); > /** > * drm_self_refresh_helper_init - Initializes self refresh helpers for a crtc > * @crtc: the crtc which supports self refresh supported displays > - * @entry_delay_ms: amount of inactivity to wait before entering self refresh > * > * Returns zero if successful or -errno on failure > */ > -int drm_self_refresh_helper_init(struct drm_crtc *crtc, > - unsigned int entry_delay_ms) > +int drm_self_refresh_helper_init(struct drm_crtc *crtc) > { > struct drm_self_refresh_data *sr_data = crtc->self_refresh_data; > > @@ -189,8 +239,18 @@ int drm_self_refresh_helper_init(struct drm_crtc *crtc, > > INIT_DELAYED_WORK(&sr_data->entry_work, > drm_self_refresh_helper_entry_work); > - sr_data->entry_delay_ms = entry_delay_ms; > sr_data->crtc = crtc; > + mutex_init(&sr_data->avg_mutex); > + ewma_psr_time_init(&sr_data->entry_avg_ms); > + ewma_psr_time_init(&sr_data->exit_avg_ms); > + > + /* > + * Seed the averages so they're non-zero (and sufficiently large > + * for even poorly performing panels). As time goes on, this will be > + * averaged out and the values will trend to their true value. > + */ > + ewma_psr_time_add(&sr_data->entry_avg_ms, SELF_REFRESH_AVG_SEED_MS); > + ewma_psr_time_add(&sr_data->exit_avg_ms, SELF_REFRESH_AVG_SEED_MS); > > crtc->self_refresh_data = sr_data; > return 0; > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > index 2f821c58007c..613404f86668 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > @@ -39,8 +39,6 @@ > #include "rockchip_drm_vop.h" > #include "rockchip_rgb.h" > > -#define VOP_SELF_REFRESH_ENTRY_DELAY_MS 100 > - > #define VOP_WIN_SET(vop, win, name, v) \ > vop_reg_set(vop, &win->phy->name, win->base, ~0, v, #name) > #define VOP_SCL_SET(vop, win, name, v) \ > @@ -1563,8 +1561,7 @@ static int vop_create_crtc(struct vop *vop) > init_completion(&vop->line_flag_completion); > crtc->port = port; > > - ret = drm_self_refresh_helper_init(crtc, > - VOP_SELF_REFRESH_ENTRY_DELAY_MS); > + ret = drm_self_refresh_helper_init(crtc); > if (ret) > DRM_DEV_DEBUG_KMS(vop->dev, > "Failed to init %s with SR helpers %d, ignoring\n", > diff --git a/include/drm/drm_self_refresh_helper.h > b/include/drm/drm_self_refresh_helper.h > index 397a583ccca7..5b79d253fb46 100644 > --- a/include/drm/drm_self_refresh_helper.h > +++ b/include/drm/drm_self_refresh_helper.h > @@ -12,9 +12,9 @@ struct drm_atomic_state; > struct drm_crtc; > > void drm_self_refresh_helper_alter_state(struct drm_atomic_state *state); > +void drm_self_refresh_helper_update_avg_times(struct drm_atomic_state *state, > + unsigned int commit_time_ms); > > -int drm_self_refresh_helper_init(struct drm_crtc *crtc, > - unsigned int entry_delay_ms); > - > +int drm_self_refresh_helper_init(struct drm_crtc *crtc); > void drm_self_refresh_helper_cleanup(struct drm_crtc *crtc); > #endif > -- > Sean Paul, Software Engineer, Google / Chromium OS > -- Sean Paul, Software Engineer, Google / Chromium OS _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
