[PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
which is done using interconnect framework. It fixes display corruption that
happens due to insufficient memory bandwidth.

Changelog:

v18: - Moved total peak bandwidth from CRTC state to plane state and removed
       dummy plane bandwidth state initialization from T186+ plane hub. This
       was suggested by Thierry Reding to v17.

     - I haven't done anything about the cursor's plane bandwidth which
       doesn't contribute to overlapping bandwidths for a small sized
       window because it works okay as-is.

v17: - No changes, re-sending for v5.14.

v16: - Implemented suggestions that were given by Michał Mirosław to v15.

     - Added r-b from Michał Mirosław to the debug-stats patch.

     - Rebased on top of a recent linux-next.

     - Removed bandwidth scaling based on width difference of src/dst
       windows since it's not actual anymore. Apparently the recent memory
       driver changes fixed problems that I witnessed before.

     - Average bandwidth calculation now won't overflow for 4k resolutions.

     - Average bandwidth calculation now uses the size of the visible
       area instead of the src area since debug stats of the memory
       controller clearly show that downscaled window takes less bandwidth,
       proportionally to the scaled size.

     - Bandwidth calculation now uses "adjusted mode" of the CRTC, which
       is what used for h/w programming, instead of the mode that was
       requested by userspace, although the two usually match in practice.

v15: - Corrected tegra_plane_icc_names[] NULL-check that was partially lost
       by accident in v14 after unsuccessful rebase.

v14: - Made improvements that were suggested by Michał Mirosław to v13:

       - Changed 'unsigned int' to 'bool'.
       - Renamed functions which calculate bandwidth state.
       - Reworked comment in the code that explains why downscaled plane
         require higher bandwidth.
       - Added round-up to bandwidth calculation.
       - Added sanity checks of the plane index and fixed out-of-bounds
         access which happened on T124 due to the cursor plane index.

v13: - No code changes. Patches missed v5.12, re-sending them for v5.13.

Dmitry Osipenko (2):
  drm/tegra: dc: Support memory bandwidth management
  drm/tegra: dc: Extend debug stats with total number of events

 drivers/gpu/drm/tegra/Kconfig |   1 +
 drivers/gpu/drm/tegra/dc.c    | 358 +++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/tegra/dc.h    |  17 ++
 drivers/gpu/drm/tegra/drm.c   |  14 ++
 drivers/gpu/drm/tegra/plane.c | 117 +++++++++++
 drivers/gpu/drm/tegra/plane.h |  16 ++
 6 files changed, 521 insertions(+), 2 deletions(-)

-- 
2.30.2

[PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
which is done using interconnect framework. It fixes display corruption that
happens due to insufficient memory bandwidth.

Changelog:

v18: - Moved total peak bandwidth from CRTC state to plane state and removed
       dummy plane bandwidth state initialization from T186+ plane hub. This
       was suggested by Thierry Reding to v17.

     - I haven't done anything about the cursor's plane bandwidth which
       doesn't contribute to overlapping bandwidths for a small sized
       window because it works okay as-is.

v17: - No changes, re-sending for v5.14.

v16: - Implemented suggestions that were given by Michał Mirosław to v15.

     - Added r-b from Michał Mirosław to the debug-stats patch.

     - Rebased on top of a recent linux-next.

     - Removed bandwidth scaling based on width difference of src/dst
       windows since it's not actual anymore. Apparently the recent memory
       driver changes fixed problems that I witnessed before.

     - Average bandwidth calculation now won't overflow for 4k resolutions.

     - Average bandwidth calculation now uses the size of the visible
       area instead of the src area since debug stats of the memory
       controller clearly show that downscaled window takes less bandwidth,
       proportionally to the scaled size.

     - Bandwidth calculation now uses "adjusted mode" of the CRTC, which
       is what used for h/w programming, instead of the mode that was
       requested by userspace, although the two usually match in practice.

v15: - Corrected tegra_plane_icc_names[] NULL-check that was partially lost
       by accident in v14 after unsuccessful rebase.

v14: - Made improvements that were suggested by Michał Mirosław to v13:

       - Changed 'unsigned int' to 'bool'.
       - Renamed functions which calculate bandwidth state.
       - Reworked comment in the code that explains why downscaled plane
         require higher bandwidth.
       - Added round-up to bandwidth calculation.
       - Added sanity checks of the plane index and fixed out-of-bounds
         access which happened on T124 due to the cursor plane index.

v13: - No code changes. Patches missed v5.12, re-sending them for v5.13.

Dmitry Osipenko (2):
  drm/tegra: dc: Support memory bandwidth management
  drm/tegra: dc: Extend debug stats with total number of events

 drivers/gpu/drm/tegra/Kconfig |   1 +
 drivers/gpu/drm/tegra/dc.c    | 358 +++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/tegra/dc.h    |  17 ++
 drivers/gpu/drm/tegra/drm.c   |  14 ++
 drivers/gpu/drm/tegra/plane.c | 117 +++++++++++
 drivers/gpu/drm/tegra/plane.h |  16 ++
 6 files changed, 521 insertions(+), 2 deletions(-)

-- 
2.30.2

[PATCH v18 1/2] drm/tegra: dc: Support memory bandwidth management

[Dmitry Osipenko]

Display controller (DC) performs isochronous memory transfers, and thus,
has a requirement for a minimum memory bandwidth that shall be fulfilled,
otherwise framebuffer data can't be fetched fast enough and this results
in a DC's data-FIFO underflow that follows by a visual corruption.

The Memory Controller drivers provide facility for memory bandwidth
management via interconnect API. Let's wire up the interconnect API
support to the DC driver in order to fix the distorted display output
on T30 Ouya, T124 TK1 and other Tegra devices.

Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
Tested-by: Nicolas Chauvet <kwizart@gmail.com> # PAZ00 T20 and TK1 T124
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/tegra/Kconfig |   1 +
 drivers/gpu/drm/tegra/dc.c    | 348 +++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/tegra/dc.h    |  12 ++
 drivers/gpu/drm/tegra/drm.c   |  14 ++
 drivers/gpu/drm/tegra/plane.c | 117 ++++++++++++
 drivers/gpu/drm/tegra/plane.h |  16 ++
 6 files changed, 506 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/Kconfig b/drivers/gpu/drm/tegra/Kconfig
index 5043dcaf1cf9..1650a448eabd 100644
--- a/drivers/gpu/drm/tegra/Kconfig
+++ b/drivers/gpu/drm/tegra/Kconfig
@@ -9,6 +9,7 @@ config DRM_TEGRA
 	select DRM_MIPI_DSI
 	select DRM_PANEL
 	select TEGRA_HOST1X
+	select INTERCONNECT
 	select IOMMU_IOVA
 	select CEC_CORE if CEC_NOTIFIER
 	help
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 074563ca586c..7dfe3250761f 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -8,6 +8,7 @@
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/iommu.h>
+#include <linux/interconnect.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/pm_runtime.h>
@@ -618,9 +619,14 @@ static int tegra_plane_atomic_check(struct drm_plane *plane,
 	struct tegra_dc *dc = to_tegra_dc(new_plane_state->crtc);
 	int err;
 
+	plane_state->peak_memory_bandwidth = 0;
+	plane_state->avg_memory_bandwidth = 0;
+
 	/* no need for further checks if the plane is being disabled */
-	if (!new_plane_state->crtc)
+	if (!new_plane_state->crtc) {
+		plane_state->total_peak_memory_bandwidth = 0;
 		return 0;
+	}
 
 	err = tegra_plane_format(new_plane_state->fb->format->format,
 				 &plane_state->format,
@@ -808,6 +814,12 @@ static struct drm_plane *tegra_primary_plane_create(struct drm_device *drm,
 	formats = dc->soc->primary_formats;
 	modifiers = dc->soc->modifiers;
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	err = drm_universal_plane_init(drm, &plane->base, possible_crtcs,
 				       &tegra_plane_funcs, formats,
 				       num_formats, modifiers, type, NULL);
@@ -845,12 +857,18 @@ static int tegra_cursor_atomic_check(struct drm_plane *plane,
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);
+	struct tegra_plane_state *plane_state = to_tegra_plane_state(new_plane_state);
 	struct tegra_plane *tegra = to_tegra_plane(plane);
 	int err;
 
+	plane_state->peak_memory_bandwidth = 0;
+	plane_state->avg_memory_bandwidth = 0;
+
 	/* no need for further checks if the plane is being disabled */
-	if (!new_plane_state->crtc)
+	if (!new_plane_state->crtc) {
+		plane_state->total_peak_memory_bandwidth = 0;
 		return 0;
+	}
 
 	/* scaling not supported for cursor */
 	if ((new_plane_state->src_w >> 16 != new_plane_state->crtc_w) ||
@@ -1035,6 +1053,12 @@ static struct drm_plane *tegra_dc_cursor_plane_create(struct drm_device *drm,
 		formats = tegra_cursor_plane_formats;
 	}
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	err = drm_universal_plane_init(drm, &plane->base, possible_crtcs,
 				       &tegra_plane_funcs, formats,
 				       num_formats, linear_modifiers,
@@ -1149,6 +1173,12 @@ static struct drm_plane *tegra_dc_overlay_plane_create(struct drm_device *drm,
 	num_formats = dc->soc->num_overlay_formats;
 	formats = dc->soc->overlay_formats;
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	if (!cursor)
 		type = DRM_PLANE_TYPE_OVERLAY;
 	else
@@ -1804,6 +1834,106 @@ static int tegra_dc_wait_idle(struct tegra_dc *dc, unsigned long timeout)
 	return -ETIMEDOUT;
 }
 
+static void
+tegra_crtc_update_memory_bandwidth(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state,
+				   bool prepare_bandwidth_transition)
+{
+	const struct tegra_plane_state *old_tegra_state, *new_tegra_state;
+	const struct tegra_dc_state *old_dc_state, *new_dc_state;
+	u32 i, new_avg_bw, old_avg_bw, new_peak_bw, old_peak_bw;
+	const struct drm_plane_state *old_plane_state;
+	const struct drm_crtc_state *old_crtc_state;
+	struct tegra_dc_window window, old_window;
+	struct tegra_dc *dc = to_tegra_dc(crtc);
+	struct tegra_plane *tegra;
+	struct drm_plane *plane;
+
+	if (dc->soc->has_nvdisplay)
+		return;
+
+	old_crtc_state = drm_atomic_get_old_crtc_state(state, crtc);
+	old_dc_state = to_const_dc_state(old_crtc_state);
+	new_dc_state = to_const_dc_state(crtc->state);
+
+	if (!crtc->state->active) {
+		if (!old_crtc_state->active)
+			return;
+
+		/*
+		 * When CRTC is disabled on DPMS, the state of attached planes
+		 * is kept unchanged. Hence we need to enforce removal of the
+		 * bandwidths from the ICC paths.
+		 */
+		drm_atomic_crtc_for_each_plane(plane, crtc) {
+			tegra = to_tegra_plane(plane);
+
+			icc_set_bw(tegra->icc_mem, 0, 0);
+			icc_set_bw(tegra->icc_mem_vfilter, 0, 0);
+		}
+
+		return;
+	}
+
+	for_each_old_plane_in_state(old_crtc_state->state, plane,
+				    old_plane_state, i) {
+		old_tegra_state = to_const_tegra_plane_state(old_plane_state);
+		new_tegra_state = to_const_tegra_plane_state(plane->state);
+		tegra = to_tegra_plane(plane);
+
+		/*
+		 * We're iterating over the global atomic state and it contains
+		 * planes from another CRTC, hence we need to filter out the
+		 * planes unrelated to this CRTC.
+		 */
+		if (tegra->dc != dc)
+			continue;
+
+		new_avg_bw = new_tegra_state->avg_memory_bandwidth;
+		old_avg_bw = old_tegra_state->avg_memory_bandwidth;
+
+		new_peak_bw = new_tegra_state->total_peak_memory_bandwidth;
+		old_peak_bw = old_tegra_state->total_peak_memory_bandwidth;
+
+		/*
+		 * See the comment related to !crtc->state->active above,
+		 * which explains why bandwidths need to be updated when
+		 * CRTC is turning ON.
+		 */
+		if (new_avg_bw == old_avg_bw && new_peak_bw == old_peak_bw &&
+		    old_crtc_state->active)
+			continue;
+
+		window.src.h = drm_rect_height(&plane->state->src) >> 16;
+		window.dst.h = drm_rect_height(&plane->state->dst);
+
+		old_window.src.h = drm_rect_height(&old_plane_state->src) >> 16;
+		old_window.dst.h = drm_rect_height(&old_plane_state->dst);
+
+		/*
+		 * During the preparation phase (atomic_begin), the memory
+		 * freq should go high before the DC changes are committed
+		 * if bandwidth requirement goes up, otherwise memory freq
+		 * should to stay high if BW requirement goes down.  The
+		 * opposite applies to the completion phase (post_commit).
+		 */
+		if (prepare_bandwidth_transition) {
+			new_avg_bw = max(old_avg_bw, new_avg_bw);
+			new_peak_bw = max(old_peak_bw, new_peak_bw);
+
+			if (tegra_plane_use_vertical_filtering(tegra, &old_window))
+				window = old_window;
+		}
+
+		icc_set_bw(tegra->icc_mem, new_avg_bw, new_peak_bw);
+
+		if (tegra_plane_use_vertical_filtering(tegra, &window))
+			icc_set_bw(tegra->icc_mem_vfilter, new_avg_bw, new_peak_bw);
+		else
+			icc_set_bw(tegra->icc_mem_vfilter, 0, 0);
+	}
+}
+
 static void tegra_crtc_atomic_disable(struct drm_crtc *crtc,
 				      struct drm_atomic_state *state)
 {
@@ -1985,6 +2115,8 @@ static void tegra_crtc_atomic_begin(struct drm_crtc *crtc,
 {
 	unsigned long flags;
 
+	tegra_crtc_update_memory_bandwidth(crtc, state, true);
+
 	if (crtc->state->event) {
 		spin_lock_irqsave(&crtc->dev->event_lock, flags);
 
@@ -2017,7 +2149,207 @@ static void tegra_crtc_atomic_flush(struct drm_crtc *crtc,
 	value = tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
 }
 
+static bool tegra_plane_is_cursor(const struct drm_plane_state *state)
+{
+	const struct tegra_dc_soc_info *soc = to_tegra_dc(state->crtc)->soc;
+	const struct drm_format_info *fmt = state->fb->format;
+	unsigned int src_w = drm_rect_width(&state->src) >> 16;
+	unsigned int dst_w = drm_rect_width(&state->dst);
+
+	if (state->plane->type != DRM_PLANE_TYPE_CURSOR)
+		return false;
+
+	if (soc->supports_cursor)
+		return true;
+
+	if (src_w != dst_w || fmt->num_planes != 1 || src_w * fmt->cpp[0] > 256)
+		return false;
+
+	return true;
+}
+
+static unsigned long
+tegra_plane_overlap_mask(struct drm_crtc_state *state,
+			 const struct drm_plane_state *plane_state)
+{
+	const struct drm_plane_state *other_state;
+	const struct tegra_plane *tegra;
+	unsigned long overlap_mask = 0;
+	struct drm_plane *plane;
+	struct drm_rect rect;
+
+	if (!plane_state->visible || !plane_state->fb)
+		return 0;
+
+	/*
+	 * Data-prefetch FIFO will easily help to overcome temporal memory
+	 * pressure if other plane overlaps with the cursor plane.
+	 */
+	if (tegra_plane_is_cursor(plane_state))
+		return 0;
+
+	drm_atomic_crtc_state_for_each_plane_state(plane, other_state, state) {
+		rect = plane_state->dst;
+
+		tegra = to_tegra_plane(other_state->plane);
+
+		if (!other_state->visible || !other_state->fb)
+			continue;
+
+		/*
+		 * Ignore cursor plane overlaps because it's not practical to
+		 * assume that it contributes to the bandwidth in overlapping
+		 * area if window width is small.
+		 */
+		if (tegra_plane_is_cursor(other_state))
+			continue;
+
+		if (drm_rect_intersect(&rect, &other_state->dst))
+			overlap_mask |= BIT(tegra->index);
+	}
+
+	return overlap_mask;
+}
+
+static int tegra_crtc_calculate_memory_bandwidth(struct drm_crtc *crtc,
+						 struct drm_atomic_state *state)
+{
+	ulong overlap_mask[TEGRA_DC_LEGACY_PLANES_NUM] = {}, mask;
+	u32 plane_peak_bw[TEGRA_DC_LEGACY_PLANES_NUM] = {};
+	bool all_planes_overlap_simultaneously = true;
+	const struct tegra_plane_state *tegra_state;
+	const struct drm_plane_state *plane_state;
+	struct tegra_dc *dc = to_tegra_dc(crtc);
+	const struct drm_crtc_state *old_state;
+	struct drm_crtc_state *new_state;
+	struct tegra_plane *tegra;
+	struct drm_plane *plane;
+
+	/*
+	 * The nv-display uses shared planes.  The algorithm below assumes
+	 * maximum 3 planes per-CRTC, this assumption isn't applicable to
+	 * the nv-display.  Note that T124 support has additional windows,
+	 * but currently they aren't supported by the driver.
+	 */
+	if (dc->soc->has_nvdisplay)
+		return 0;
+
+	new_state = drm_atomic_get_new_crtc_state(state, crtc);
+	old_state = drm_atomic_get_old_crtc_state(state, crtc);
+
+	/*
+	 * For overlapping planes pixel's data is fetched for each plane at
+	 * the same time, hence bandwidths are accumulated in this case.
+	 * This needs to be taken into account for calculating total bandwidth
+	 * consumed by all planes.
+	 *
+	 * Here we get the overlapping state of each plane, which is a
+	 * bitmask of plane indices telling with what planes there is an
+	 * overlap. Note that bitmask[plane] includes BIT(plane) in order
+	 * to make further code nicer and simpler.
+	 */
+	drm_atomic_crtc_state_for_each_plane_state(plane, plane_state, new_state) {
+		tegra_state = to_const_tegra_plane_state(plane_state);
+		tegra = to_tegra_plane(plane);
+
+		if (WARN_ON_ONCE(tegra->index >= TEGRA_DC_LEGACY_PLANES_NUM))
+			return -EINVAL;
+
+		plane_peak_bw[tegra->index] = tegra_state->peak_memory_bandwidth;
+		mask = tegra_plane_overlap_mask(new_state, plane_state);
+		overlap_mask[tegra->index] = mask;
+
+		if (hweight_long(mask) != 3)
+			all_planes_overlap_simultaneously = false;
+	}
+
+	/*
+	 * Then we calculate maximum bandwidth of each plane state.
+	 * The bandwidth includes the plane BW + BW of the "simultaneously"
+	 * overlapping planes, where "simultaneously" means areas where DC
+	 * fetches from the planes simultaneously during of scan-out process.
+	 *
+	 * For example, if plane A overlaps with planes B and C, but B and C
+	 * don't overlap, then the peak bandwidth will be either in area where
+	 * A-and-B or A-and-C planes overlap.
+	 *
+	 * The plane_peak_bw[] contains peak memory bandwidth values of
+	 * each plane, this information is needed by interconnect provider
+	 * in order to set up latency allowance based on the peak BW, see
+	 * tegra_crtc_update_memory_bandwidth().
+	 */
+	drm_atomic_crtc_state_for_each_plane_state(plane, plane_state, new_state) {
+		u32 i, old_peak_bw, new_peak_bw, overlap_bw = 0;
+
+		/*
+		 * Note that plane's atomic check doesn't touch the
+		 * total_peak_memory_bandwidth of enabled plane, hence the
+		 * current state contains the old bandwidth state from the
+		 * previous CRTC commit.
+		 */
+		tegra_state = to_const_tegra_plane_state(plane_state);
+		tegra = to_tegra_plane(plane);
+
+		for_each_set_bit(i, &overlap_mask[tegra->index], 3) {
+			if (i == tegra->index)
+				continue;
+
+			if (all_planes_overlap_simultaneously)
+				overlap_bw += plane_peak_bw[i];
+			else
+				overlap_bw = max(overlap_bw, plane_peak_bw[i]);
+		}
+
+		new_peak_bw = plane_peak_bw[tegra->index] + overlap_bw;
+		old_peak_bw = tegra_state->total_peak_memory_bandwidth;
+
+		/*
+		 * If plane's peak bandwidth changed (for example plane isn't
+		 * overlapped anymore) and plane isn't in the atomic state,
+		 * then add plane to the state in order to have the bandwidth
+		 * updated.
+		 */
+		if (old_peak_bw != new_peak_bw) {
+			struct tegra_plane_state *new_tegra_state;
+			struct drm_plane_state *new_plane_state;
+
+			new_plane_state = drm_atomic_get_plane_state(state, plane);
+			if (IS_ERR(new_plane_state))
+				return PTR_ERR(new_plane_state);
+
+			new_tegra_state = to_tegra_plane_state(new_plane_state);
+			new_tegra_state->total_peak_memory_bandwidth = new_peak_bw;
+		}
+	}
+
+	return 0;
+}
+
+static int tegra_crtc_atomic_check(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	int err;
+
+	err = tegra_crtc_calculate_memory_bandwidth(crtc, state);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+void tegra_crtc_atomic_post_commit(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	/*
+	 * Display bandwidth is allowed to go down only once hardware state
+	 * is known to be armed, i.e. state was committed and VBLANK event
+	 * received.
+	 */
+	tegra_crtc_update_memory_bandwidth(crtc, state, false);
+}
+
 static const struct drm_crtc_helper_funcs tegra_crtc_helper_funcs = {
+	.atomic_check = tegra_crtc_atomic_check,
 	.atomic_begin = tegra_crtc_atomic_begin,
 	.atomic_flush = tegra_crtc_atomic_flush,
 	.atomic_enable = tegra_crtc_atomic_enable,
@@ -2343,7 +2675,9 @@ static const struct tegra_dc_soc_info tegra20_dc_soc_info = {
 	.overlay_formats = tegra20_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = true,
+	.has_win_b_vfilter_mem_client = true,
 	.has_win_c_without_vert_filter = true,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_dc_soc_info tegra30_dc_soc_info = {
@@ -2363,7 +2697,9 @@ static const struct tegra_dc_soc_info tegra30_dc_soc_info = {
 	.overlay_formats = tegra20_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = true,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = true,
 };
 
 static const struct tegra_dc_soc_info tegra114_dc_soc_info = {
@@ -2383,7 +2719,9 @@ static const struct tegra_dc_soc_info tegra114_dc_soc_info = {
 	.overlay_formats = tegra114_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = true,
 };
 
 static const struct tegra_dc_soc_info tegra124_dc_soc_info = {
@@ -2403,7 +2741,9 @@ static const struct tegra_dc_soc_info tegra124_dc_soc_info = {
 	.overlay_formats = tegra124_overlay_formats,
 	.modifiers = tegra124_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_dc_soc_info tegra210_dc_soc_info = {
@@ -2423,7 +2763,9 @@ static const struct tegra_dc_soc_info tegra210_dc_soc_info = {
 	.overlay_formats = tegra114_overlay_formats,
 	.modifiers = tegra124_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_windowgroup_soc tegra186_dc_wgrps[] = {
@@ -2473,6 +2815,7 @@ static const struct tegra_dc_soc_info tegra186_dc_soc_info = {
 	.has_nvdisplay = true,
 	.wgrps = tegra186_dc_wgrps,
 	.num_wgrps = ARRAY_SIZE(tegra186_dc_wgrps),
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_windowgroup_soc tegra194_dc_wgrps[] = {
@@ -2522,6 +2865,7 @@ static const struct tegra_dc_soc_info tegra194_dc_soc_info = {
 	.has_nvdisplay = true,
 	.wgrps = tegra194_dc_wgrps,
 	.num_wgrps = ARRAY_SIZE(tegra194_dc_wgrps),
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct of_device_id tegra_dc_of_match[] = {
diff --git a/drivers/gpu/drm/tegra/dc.h b/drivers/gpu/drm/tegra/dc.h
index 29f19c3c6149..581263c7614a 100644
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -15,6 +15,8 @@
 
 struct tegra_output;
 
+#define TEGRA_DC_LEGACY_PLANES_NUM	7
+
 struct tegra_dc_state {
 	struct drm_crtc_state base;
 
@@ -33,6 +35,12 @@ static inline struct tegra_dc_state *to_dc_state(struct drm_crtc_state *state)
 	return NULL;
 }
 
+static inline const struct tegra_dc_state *
+to_const_dc_state(const struct drm_crtc_state *state)
+{
+	return to_dc_state((struct drm_crtc_state *)state);
+}
+
 struct tegra_dc_stats {
 	unsigned long frames;
 	unsigned long vblank;
@@ -66,7 +74,9 @@ struct tegra_dc_soc_info {
 	unsigned int num_overlay_formats;
 	const u64 *modifiers;
 	bool has_win_a_without_filters;
+	bool has_win_b_vfilter_mem_client;
 	bool has_win_c_without_vert_filter;
+	bool plane_tiled_memory_bandwidth_x2;
 };
 
 struct tegra_dc {
@@ -152,6 +162,8 @@ int tegra_dc_state_setup_clock(struct tegra_dc *dc,
 			       struct drm_crtc_state *crtc_state,
 			       struct clk *clk, unsigned long pclk,
 			       unsigned int div);
+void tegra_crtc_atomic_post_commit(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state);
 
 /* from rgb.c */
 int tegra_dc_rgb_probe(struct tegra_dc *dc);
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index c850991241e8..ca1f66fd8d63 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -25,6 +25,7 @@
 #include <asm/dma-iommu.h>
 #endif
 
+#include "dc.h"
 #include "drm.h"
 #include "gem.h"
 
@@ -64,6 +65,17 @@ static const struct drm_mode_config_funcs tegra_drm_mode_config_funcs = {
 	.atomic_commit = drm_atomic_helper_commit,
 };
 
+static void tegra_atomic_post_commit(struct drm_device *drm,
+				     struct drm_atomic_state *old_state)
+{
+	struct drm_crtc_state *old_crtc_state __maybe_unused;
+	struct drm_crtc *crtc;
+	unsigned int i;
+
+	for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i)
+		tegra_crtc_atomic_post_commit(crtc, old_state);
+}
+
 static void tegra_atomic_commit_tail(struct drm_atomic_state *old_state)
 {
 	struct drm_device *drm = old_state->dev;
@@ -83,6 +95,8 @@ static void tegra_atomic_commit_tail(struct drm_atomic_state *old_state)
 	} else {
 		drm_atomic_helper_commit_tail_rpm(old_state);
 	}
+
+	tegra_atomic_post_commit(drm, old_state);
 }
 
 static const struct drm_mode_config_helper_funcs
diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c
index 2e11b4b1f702..ad6f5fbec00c 100644
--- a/drivers/gpu/drm/tegra/plane.c
+++ b/drivers/gpu/drm/tegra/plane.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/iommu.h>
+#include <linux/interconnect.h>
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
@@ -64,6 +65,9 @@ tegra_plane_atomic_duplicate_state(struct drm_plane *plane)
 	copy->reflect_x = state->reflect_x;
 	copy->reflect_y = state->reflect_y;
 	copy->opaque = state->opaque;
+	copy->total_peak_memory_bandwidth = state->total_peak_memory_bandwidth;
+	copy->peak_memory_bandwidth = state->peak_memory_bandwidth;
+	copy->avg_memory_bandwidth = state->avg_memory_bandwidth;
 
 	for (i = 0; i < 2; i++)
 		copy->blending[i] = state->blending[i];
@@ -244,6 +248,78 @@ void tegra_plane_cleanup_fb(struct drm_plane *plane,
 		tegra_dc_unpin(dc, to_tegra_plane_state(state));
 }
 
+static int tegra_plane_calculate_memory_bandwidth(struct drm_plane_state *state)
+{
+	struct tegra_plane_state *tegra_state = to_tegra_plane_state(state);
+	unsigned int i, bpp, dst_w, dst_h, src_w, src_h, mul;
+	const struct tegra_dc_soc_info *soc;
+	const struct drm_format_info *fmt;
+	struct drm_crtc_state *crtc_state;
+	u64 avg_bandwidth, peak_bandwidth;
+
+	if (!state->visible)
+		return 0;
+
+	crtc_state = drm_atomic_get_new_crtc_state(state->state, state->crtc);
+	if (!crtc_state)
+		return -EINVAL;
+
+	src_w = drm_rect_width(&state->src) >> 16;
+	src_h = drm_rect_height(&state->src) >> 16;
+	dst_w = drm_rect_width(&state->dst);
+	dst_h = drm_rect_height(&state->dst);
+
+	fmt = state->fb->format;
+	soc = to_tegra_dc(state->crtc)->soc;
+
+	/*
+	 * Note that real memory bandwidth vary depending on format and
+	 * memory layout, we are not taking that into account because small
+	 * estimation error isn't important since bandwidth is rounded up
+	 * anyway.
+	 */
+	for (i = 0, bpp = 0; i < fmt->num_planes; i++) {
+		unsigned int bpp_plane = fmt->cpp[i] * 8;
+
+		/*
+		 * Sub-sampling is relevant for chroma planes only and vertical
+		 * readouts are not cached, hence only horizontal sub-sampling
+		 * matters.
+		 */
+		if (i > 0)
+			bpp_plane /= fmt->hsub;
+
+		bpp += bpp_plane;
+	}
+
+	/* average bandwidth in kbytes/sec */
+	avg_bandwidth  = min(src_w, dst_w) * min(src_h, dst_h);
+	avg_bandwidth *= drm_mode_vrefresh(&crtc_state->adjusted_mode);
+	avg_bandwidth  = DIV_ROUND_UP(avg_bandwidth * bpp, 8) + 999;
+	do_div(avg_bandwidth, 1000);
+
+	/* mode.clock in kHz, peak bandwidth in kbytes/sec */
+	peak_bandwidth = DIV_ROUND_UP(crtc_state->adjusted_mode.clock * bpp, 8);
+
+	/*
+	 * Tegra30/114 Memory Controller can't interleave DC memory requests
+	 * for the tiled windows because DC uses 16-bytes atom, while DDR3
+	 * uses 32-bytes atom.  Hence there is x2 memory overfetch for tiled
+	 * framebuffer and DDR3 on these SoCs.
+	 */
+	if (soc->plane_tiled_memory_bandwidth_x2 &&
+	    tegra_state->tiling.mode == TEGRA_BO_TILING_MODE_TILED)
+		mul = 2;
+	else
+		mul = 1;
+
+	/* ICC bandwidth in kbytes/sec */
+	tegra_state->peak_memory_bandwidth = kBps_to_icc(peak_bandwidth) * mul;
+	tegra_state->avg_memory_bandwidth  = kBps_to_icc(avg_bandwidth)  * mul;
+
+	return 0;
+}
+
 int tegra_plane_state_add(struct tegra_plane *plane,
 			  struct drm_plane_state *state)
 {
@@ -262,6 +338,10 @@ int tegra_plane_state_add(struct tegra_plane *plane,
 	if (err < 0)
 		return err;
 
+	err = tegra_plane_calculate_memory_bandwidth(state);
+	if (err < 0)
+		return err;
+
 	tegra = to_dc_state(crtc_state);
 
 	tegra->planes |= WIN_A_ACT_REQ << plane->index;
@@ -627,3 +707,40 @@ int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
 
 	return 0;
 }
+
+static const char * const tegra_plane_icc_names[TEGRA_DC_LEGACY_PLANES_NUM] = {
+	"wina", "winb", "winc", NULL, NULL, NULL, "cursor",
+};
+
+int tegra_plane_interconnect_init(struct tegra_plane *plane)
+{
+	const char *icc_name = tegra_plane_icc_names[plane->index];
+	struct device *dev = plane->dc->dev;
+	struct tegra_dc *dc = plane->dc;
+	int err;
+
+	if (WARN_ON(plane->index >= TEGRA_DC_LEGACY_PLANES_NUM) ||
+	    WARN_ON(!tegra_plane_icc_names[plane->index]))
+		return -EINVAL;
+
+	plane->icc_mem = devm_of_icc_get(dev, icc_name);
+	err = PTR_ERR_OR_ZERO(plane->icc_mem);
+	if (err) {
+		dev_err_probe(dev, err, "failed to get %s interconnect\n",
+			      icc_name);
+		return err;
+	}
+
+	/* plane B on T20/30 has a dedicated memory client for a 6-tap vertical filter */
+	if (plane->index == 1 && dc->soc->has_win_b_vfilter_mem_client) {
+		plane->icc_mem_vfilter = devm_of_icc_get(dev, "winb-vfilter");
+		err = PTR_ERR_OR_ZERO(plane->icc_mem_vfilter);
+		if (err) {
+			dev_err_probe(dev, err, "failed to get %s interconnect\n",
+				      "winb-vfilter");
+			return err;
+		}
+	}
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/tegra/plane.h b/drivers/gpu/drm/tegra/plane.h
index c691dd79b27b..31ff7721e9a9 100644
--- a/drivers/gpu/drm/tegra/plane.h
+++ b/drivers/gpu/drm/tegra/plane.h
@@ -8,6 +8,7 @@
 
 #include <drm/drm_plane.h>
 
+struct icc_path;
 struct tegra_bo;
 struct tegra_dc;
 
@@ -16,6 +17,9 @@ struct tegra_plane {
 	struct tegra_dc *dc;
 	unsigned int offset;
 	unsigned int index;
+
+	struct icc_path *icc_mem;
+	struct icc_path *icc_mem_vfilter;
 };
 
 struct tegra_cursor {
@@ -52,6 +56,11 @@ struct tegra_plane_state {
 	/* used for legacy blending support only */
 	struct tegra_plane_legacy_blending_state blending[2];
 	bool opaque;
+
+	/* bandwidths are in ICC units, i.e. kbytes/sec */
+	u32 total_peak_memory_bandwidth;
+	u32 peak_memory_bandwidth;
+	u32 avg_memory_bandwidth;
 };
 
 static inline struct tegra_plane_state *
@@ -63,6 +72,12 @@ to_tegra_plane_state(struct drm_plane_state *state)
 	return NULL;
 }
 
+static inline const struct tegra_plane_state *
+to_const_tegra_plane_state(const struct drm_plane_state *state)
+{
+	return to_tegra_plane_state((struct drm_plane_state *)state);
+}
+
 extern const struct drm_plane_funcs tegra_plane_funcs;
 
 int tegra_plane_prepare_fb(struct drm_plane *plane,
@@ -77,5 +92,6 @@ int tegra_plane_format(u32 fourcc, u32 *format, u32 *swap);
 bool tegra_plane_format_is_yuv(unsigned int format, bool *planar);
 int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
 				   struct tegra_plane_state *state);
+int tegra_plane_interconnect_init(struct tegra_plane *plane);
 
 #endif /* TEGRA_PLANE_H */
-- 
2.30.2

[PATCH v18 1/2] drm/tegra: dc: Support memory bandwidth management

[Dmitry Osipenko]

Display controller (DC) performs isochronous memory transfers, and thus,
has a requirement for a minimum memory bandwidth that shall be fulfilled,
otherwise framebuffer data can't be fetched fast enough and this results
in a DC's data-FIFO underflow that follows by a visual corruption.

The Memory Controller drivers provide facility for memory bandwidth
management via interconnect API. Let's wire up the interconnect API
support to the DC driver in order to fix the distorted display output
on T30 Ouya, T124 TK1 and other Tegra devices.

Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
Tested-by: Nicolas Chauvet <kwizart@gmail.com> # PAZ00 T20 and TK1 T124
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/tegra/Kconfig |   1 +
 drivers/gpu/drm/tegra/dc.c    | 348 +++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/tegra/dc.h    |  12 ++
 drivers/gpu/drm/tegra/drm.c   |  14 ++
 drivers/gpu/drm/tegra/plane.c | 117 ++++++++++++
 drivers/gpu/drm/tegra/plane.h |  16 ++
 6 files changed, 506 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/Kconfig b/drivers/gpu/drm/tegra/Kconfig
index 5043dcaf1cf9..1650a448eabd 100644
--- a/drivers/gpu/drm/tegra/Kconfig
+++ b/drivers/gpu/drm/tegra/Kconfig
@@ -9,6 +9,7 @@ config DRM_TEGRA
 	select DRM_MIPI_DSI
 	select DRM_PANEL
 	select TEGRA_HOST1X
+	select INTERCONNECT
 	select IOMMU_IOVA
 	select CEC_CORE if CEC_NOTIFIER
 	help
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 074563ca586c..7dfe3250761f 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -8,6 +8,7 @@
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/iommu.h>
+#include <linux/interconnect.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/pm_runtime.h>
@@ -618,9 +619,14 @@ static int tegra_plane_atomic_check(struct drm_plane *plane,
 	struct tegra_dc *dc = to_tegra_dc(new_plane_state->crtc);
 	int err;
 
+	plane_state->peak_memory_bandwidth = 0;
+	plane_state->avg_memory_bandwidth = 0;
+
 	/* no need for further checks if the plane is being disabled */
-	if (!new_plane_state->crtc)
+	if (!new_plane_state->crtc) {
+		plane_state->total_peak_memory_bandwidth = 0;
 		return 0;
+	}
 
 	err = tegra_plane_format(new_plane_state->fb->format->format,
 				 &plane_state->format,
@@ -808,6 +814,12 @@ static struct drm_plane *tegra_primary_plane_create(struct drm_device *drm,
 	formats = dc->soc->primary_formats;
 	modifiers = dc->soc->modifiers;
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	err = drm_universal_plane_init(drm, &plane->base, possible_crtcs,
 				       &tegra_plane_funcs, formats,
 				       num_formats, modifiers, type, NULL);
@@ -845,12 +857,18 @@ static int tegra_cursor_atomic_check(struct drm_plane *plane,
 {
 	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
 										 plane);
+	struct tegra_plane_state *plane_state = to_tegra_plane_state(new_plane_state);
 	struct tegra_plane *tegra = to_tegra_plane(plane);
 	int err;
 
+	plane_state->peak_memory_bandwidth = 0;
+	plane_state->avg_memory_bandwidth = 0;
+
 	/* no need for further checks if the plane is being disabled */
-	if (!new_plane_state->crtc)
+	if (!new_plane_state->crtc) {
+		plane_state->total_peak_memory_bandwidth = 0;
 		return 0;
+	}
 
 	/* scaling not supported for cursor */
 	if ((new_plane_state->src_w >> 16 != new_plane_state->crtc_w) ||
@@ -1035,6 +1053,12 @@ static struct drm_plane *tegra_dc_cursor_plane_create(struct drm_device *drm,
 		formats = tegra_cursor_plane_formats;
 	}
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	err = drm_universal_plane_init(drm, &plane->base, possible_crtcs,
 				       &tegra_plane_funcs, formats,
 				       num_formats, linear_modifiers,
@@ -1149,6 +1173,12 @@ static struct drm_plane *tegra_dc_overlay_plane_create(struct drm_device *drm,
 	num_formats = dc->soc->num_overlay_formats;
 	formats = dc->soc->overlay_formats;
 
+	err = tegra_plane_interconnect_init(plane);
+	if (err) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
 	if (!cursor)
 		type = DRM_PLANE_TYPE_OVERLAY;
 	else
@@ -1804,6 +1834,106 @@ static int tegra_dc_wait_idle(struct tegra_dc *dc, unsigned long timeout)
 	return -ETIMEDOUT;
 }
 
+static void
+tegra_crtc_update_memory_bandwidth(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state,
+				   bool prepare_bandwidth_transition)
+{
+	const struct tegra_plane_state *old_tegra_state, *new_tegra_state;
+	const struct tegra_dc_state *old_dc_state, *new_dc_state;
+	u32 i, new_avg_bw, old_avg_bw, new_peak_bw, old_peak_bw;
+	const struct drm_plane_state *old_plane_state;
+	const struct drm_crtc_state *old_crtc_state;
+	struct tegra_dc_window window, old_window;
+	struct tegra_dc *dc = to_tegra_dc(crtc);
+	struct tegra_plane *tegra;
+	struct drm_plane *plane;
+
+	if (dc->soc->has_nvdisplay)
+		return;
+
+	old_crtc_state = drm_atomic_get_old_crtc_state(state, crtc);
+	old_dc_state = to_const_dc_state(old_crtc_state);
+	new_dc_state = to_const_dc_state(crtc->state);
+
+	if (!crtc->state->active) {
+		if (!old_crtc_state->active)
+			return;
+
+		/*
+		 * When CRTC is disabled on DPMS, the state of attached planes
+		 * is kept unchanged. Hence we need to enforce removal of the
+		 * bandwidths from the ICC paths.
+		 */
+		drm_atomic_crtc_for_each_plane(plane, crtc) {
+			tegra = to_tegra_plane(plane);
+
+			icc_set_bw(tegra->icc_mem, 0, 0);
+			icc_set_bw(tegra->icc_mem_vfilter, 0, 0);
+		}
+
+		return;
+	}
+
+	for_each_old_plane_in_state(old_crtc_state->state, plane,
+				    old_plane_state, i) {
+		old_tegra_state = to_const_tegra_plane_state(old_plane_state);
+		new_tegra_state = to_const_tegra_plane_state(plane->state);
+		tegra = to_tegra_plane(plane);
+
+		/*
+		 * We're iterating over the global atomic state and it contains
+		 * planes from another CRTC, hence we need to filter out the
+		 * planes unrelated to this CRTC.
+		 */
+		if (tegra->dc != dc)
+			continue;
+
+		new_avg_bw = new_tegra_state->avg_memory_bandwidth;
+		old_avg_bw = old_tegra_state->avg_memory_bandwidth;
+
+		new_peak_bw = new_tegra_state->total_peak_memory_bandwidth;
+		old_peak_bw = old_tegra_state->total_peak_memory_bandwidth;
+
+		/*
+		 * See the comment related to !crtc->state->active above,
+		 * which explains why bandwidths need to be updated when
+		 * CRTC is turning ON.
+		 */
+		if (new_avg_bw == old_avg_bw && new_peak_bw == old_peak_bw &&
+		    old_crtc_state->active)
+			continue;
+
+		window.src.h = drm_rect_height(&plane->state->src) >> 16;
+		window.dst.h = drm_rect_height(&plane->state->dst);
+
+		old_window.src.h = drm_rect_height(&old_plane_state->src) >> 16;
+		old_window.dst.h = drm_rect_height(&old_plane_state->dst);
+
+		/*
+		 * During the preparation phase (atomic_begin), the memory
+		 * freq should go high before the DC changes are committed
+		 * if bandwidth requirement goes up, otherwise memory freq
+		 * should to stay high if BW requirement goes down.  The
+		 * opposite applies to the completion phase (post_commit).
+		 */
+		if (prepare_bandwidth_transition) {
+			new_avg_bw = max(old_avg_bw, new_avg_bw);
+			new_peak_bw = max(old_peak_bw, new_peak_bw);
+
+			if (tegra_plane_use_vertical_filtering(tegra, &old_window))
+				window = old_window;
+		}
+
+		icc_set_bw(tegra->icc_mem, new_avg_bw, new_peak_bw);
+
+		if (tegra_plane_use_vertical_filtering(tegra, &window))
+			icc_set_bw(tegra->icc_mem_vfilter, new_avg_bw, new_peak_bw);
+		else
+			icc_set_bw(tegra->icc_mem_vfilter, 0, 0);
+	}
+}
+
 static void tegra_crtc_atomic_disable(struct drm_crtc *crtc,
 				      struct drm_atomic_state *state)
 {
@@ -1985,6 +2115,8 @@ static void tegra_crtc_atomic_begin(struct drm_crtc *crtc,
 {
 	unsigned long flags;
 
+	tegra_crtc_update_memory_bandwidth(crtc, state, true);
+
 	if (crtc->state->event) {
 		spin_lock_irqsave(&crtc->dev->event_lock, flags);
 
@@ -2017,7 +2149,207 @@ static void tegra_crtc_atomic_flush(struct drm_crtc *crtc,
 	value = tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
 }
 
+static bool tegra_plane_is_cursor(const struct drm_plane_state *state)
+{
+	const struct tegra_dc_soc_info *soc = to_tegra_dc(state->crtc)->soc;
+	const struct drm_format_info *fmt = state->fb->format;
+	unsigned int src_w = drm_rect_width(&state->src) >> 16;
+	unsigned int dst_w = drm_rect_width(&state->dst);
+
+	if (state->plane->type != DRM_PLANE_TYPE_CURSOR)
+		return false;
+
+	if (soc->supports_cursor)
+		return true;
+
+	if (src_w != dst_w || fmt->num_planes != 1 || src_w * fmt->cpp[0] > 256)
+		return false;
+
+	return true;
+}
+
+static unsigned long
+tegra_plane_overlap_mask(struct drm_crtc_state *state,
+			 const struct drm_plane_state *plane_state)
+{
+	const struct drm_plane_state *other_state;
+	const struct tegra_plane *tegra;
+	unsigned long overlap_mask = 0;
+	struct drm_plane *plane;
+	struct drm_rect rect;
+
+	if (!plane_state->visible || !plane_state->fb)
+		return 0;
+
+	/*
+	 * Data-prefetch FIFO will easily help to overcome temporal memory
+	 * pressure if other plane overlaps with the cursor plane.
+	 */
+	if (tegra_plane_is_cursor(plane_state))
+		return 0;
+
+	drm_atomic_crtc_state_for_each_plane_state(plane, other_state, state) {
+		rect = plane_state->dst;
+
+		tegra = to_tegra_plane(other_state->plane);
+
+		if (!other_state->visible || !other_state->fb)
+			continue;
+
+		/*
+		 * Ignore cursor plane overlaps because it's not practical to
+		 * assume that it contributes to the bandwidth in overlapping
+		 * area if window width is small.
+		 */
+		if (tegra_plane_is_cursor(other_state))
+			continue;
+
+		if (drm_rect_intersect(&rect, &other_state->dst))
+			overlap_mask |= BIT(tegra->index);
+	}
+
+	return overlap_mask;
+}
+
+static int tegra_crtc_calculate_memory_bandwidth(struct drm_crtc *crtc,
+						 struct drm_atomic_state *state)
+{
+	ulong overlap_mask[TEGRA_DC_LEGACY_PLANES_NUM] = {}, mask;
+	u32 plane_peak_bw[TEGRA_DC_LEGACY_PLANES_NUM] = {};
+	bool all_planes_overlap_simultaneously = true;
+	const struct tegra_plane_state *tegra_state;
+	const struct drm_plane_state *plane_state;
+	struct tegra_dc *dc = to_tegra_dc(crtc);
+	const struct drm_crtc_state *old_state;
+	struct drm_crtc_state *new_state;
+	struct tegra_plane *tegra;
+	struct drm_plane *plane;
+
+	/*
+	 * The nv-display uses shared planes.  The algorithm below assumes
+	 * maximum 3 planes per-CRTC, this assumption isn't applicable to
+	 * the nv-display.  Note that T124 support has additional windows,
+	 * but currently they aren't supported by the driver.
+	 */
+	if (dc->soc->has_nvdisplay)
+		return 0;
+
+	new_state = drm_atomic_get_new_crtc_state(state, crtc);
+	old_state = drm_atomic_get_old_crtc_state(state, crtc);
+
+	/*
+	 * For overlapping planes pixel's data is fetched for each plane at
+	 * the same time, hence bandwidths are accumulated in this case.
+	 * This needs to be taken into account for calculating total bandwidth
+	 * consumed by all planes.
+	 *
+	 * Here we get the overlapping state of each plane, which is a
+	 * bitmask of plane indices telling with what planes there is an
+	 * overlap. Note that bitmask[plane] includes BIT(plane) in order
+	 * to make further code nicer and simpler.
+	 */
+	drm_atomic_crtc_state_for_each_plane_state(plane, plane_state, new_state) {
+		tegra_state = to_const_tegra_plane_state(plane_state);
+		tegra = to_tegra_plane(plane);
+
+		if (WARN_ON_ONCE(tegra->index >= TEGRA_DC_LEGACY_PLANES_NUM))
+			return -EINVAL;
+
+		plane_peak_bw[tegra->index] = tegra_state->peak_memory_bandwidth;
+		mask = tegra_plane_overlap_mask(new_state, plane_state);
+		overlap_mask[tegra->index] = mask;
+
+		if (hweight_long(mask) != 3)
+			all_planes_overlap_simultaneously = false;
+	}
+
+	/*
+	 * Then we calculate maximum bandwidth of each plane state.
+	 * The bandwidth includes the plane BW + BW of the "simultaneously"
+	 * overlapping planes, where "simultaneously" means areas where DC
+	 * fetches from the planes simultaneously during of scan-out process.
+	 *
+	 * For example, if plane A overlaps with planes B and C, but B and C
+	 * don't overlap, then the peak bandwidth will be either in area where
+	 * A-and-B or A-and-C planes overlap.
+	 *
+	 * The plane_peak_bw[] contains peak memory bandwidth values of
+	 * each plane, this information is needed by interconnect provider
+	 * in order to set up latency allowance based on the peak BW, see
+	 * tegra_crtc_update_memory_bandwidth().
+	 */
+	drm_atomic_crtc_state_for_each_plane_state(plane, plane_state, new_state) {
+		u32 i, old_peak_bw, new_peak_bw, overlap_bw = 0;
+
+		/*
+		 * Note that plane's atomic check doesn't touch the
+		 * total_peak_memory_bandwidth of enabled plane, hence the
+		 * current state contains the old bandwidth state from the
+		 * previous CRTC commit.
+		 */
+		tegra_state = to_const_tegra_plane_state(plane_state);
+		tegra = to_tegra_plane(plane);
+
+		for_each_set_bit(i, &overlap_mask[tegra->index], 3) {
+			if (i == tegra->index)
+				continue;
+
+			if (all_planes_overlap_simultaneously)
+				overlap_bw += plane_peak_bw[i];
+			else
+				overlap_bw = max(overlap_bw, plane_peak_bw[i]);
+		}
+
+		new_peak_bw = plane_peak_bw[tegra->index] + overlap_bw;
+		old_peak_bw = tegra_state->total_peak_memory_bandwidth;
+
+		/*
+		 * If plane's peak bandwidth changed (for example plane isn't
+		 * overlapped anymore) and plane isn't in the atomic state,
+		 * then add plane to the state in order to have the bandwidth
+		 * updated.
+		 */
+		if (old_peak_bw != new_peak_bw) {
+			struct tegra_plane_state *new_tegra_state;
+			struct drm_plane_state *new_plane_state;
+
+			new_plane_state = drm_atomic_get_plane_state(state, plane);
+			if (IS_ERR(new_plane_state))
+				return PTR_ERR(new_plane_state);
+
+			new_tegra_state = to_tegra_plane_state(new_plane_state);
+			new_tegra_state->total_peak_memory_bandwidth = new_peak_bw;
+		}
+	}
+
+	return 0;
+}
+
+static int tegra_crtc_atomic_check(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	int err;
+
+	err = tegra_crtc_calculate_memory_bandwidth(crtc, state);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+void tegra_crtc_atomic_post_commit(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	/*
+	 * Display bandwidth is allowed to go down only once hardware state
+	 * is known to be armed, i.e. state was committed and VBLANK event
+	 * received.
+	 */
+	tegra_crtc_update_memory_bandwidth(crtc, state, false);
+}
+
 static const struct drm_crtc_helper_funcs tegra_crtc_helper_funcs = {
+	.atomic_check = tegra_crtc_atomic_check,
 	.atomic_begin = tegra_crtc_atomic_begin,
 	.atomic_flush = tegra_crtc_atomic_flush,
 	.atomic_enable = tegra_crtc_atomic_enable,
@@ -2343,7 +2675,9 @@ static const struct tegra_dc_soc_info tegra20_dc_soc_info = {
 	.overlay_formats = tegra20_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = true,
+	.has_win_b_vfilter_mem_client = true,
 	.has_win_c_without_vert_filter = true,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_dc_soc_info tegra30_dc_soc_info = {
@@ -2363,7 +2697,9 @@ static const struct tegra_dc_soc_info tegra30_dc_soc_info = {
 	.overlay_formats = tegra20_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = true,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = true,
 };
 
 static const struct tegra_dc_soc_info tegra114_dc_soc_info = {
@@ -2383,7 +2719,9 @@ static const struct tegra_dc_soc_info tegra114_dc_soc_info = {
 	.overlay_formats = tegra114_overlay_formats,
 	.modifiers = tegra20_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = true,
 };
 
 static const struct tegra_dc_soc_info tegra124_dc_soc_info = {
@@ -2403,7 +2741,9 @@ static const struct tegra_dc_soc_info tegra124_dc_soc_info = {
 	.overlay_formats = tegra124_overlay_formats,
 	.modifiers = tegra124_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_dc_soc_info tegra210_dc_soc_info = {
@@ -2423,7 +2763,9 @@ static const struct tegra_dc_soc_info tegra210_dc_soc_info = {
 	.overlay_formats = tegra114_overlay_formats,
 	.modifiers = tegra124_modifiers,
 	.has_win_a_without_filters = false,
+	.has_win_b_vfilter_mem_client = false,
 	.has_win_c_without_vert_filter = false,
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_windowgroup_soc tegra186_dc_wgrps[] = {
@@ -2473,6 +2815,7 @@ static const struct tegra_dc_soc_info tegra186_dc_soc_info = {
 	.has_nvdisplay = true,
 	.wgrps = tegra186_dc_wgrps,
 	.num_wgrps = ARRAY_SIZE(tegra186_dc_wgrps),
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct tegra_windowgroup_soc tegra194_dc_wgrps[] = {
@@ -2522,6 +2865,7 @@ static const struct tegra_dc_soc_info tegra194_dc_soc_info = {
 	.has_nvdisplay = true,
 	.wgrps = tegra194_dc_wgrps,
 	.num_wgrps = ARRAY_SIZE(tegra194_dc_wgrps),
+	.plane_tiled_memory_bandwidth_x2 = false,
 };
 
 static const struct of_device_id tegra_dc_of_match[] = {
diff --git a/drivers/gpu/drm/tegra/dc.h b/drivers/gpu/drm/tegra/dc.h
index 29f19c3c6149..581263c7614a 100644
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -15,6 +15,8 @@
 
 struct tegra_output;
 
+#define TEGRA_DC_LEGACY_PLANES_NUM	7
+
 struct tegra_dc_state {
 	struct drm_crtc_state base;
 
@@ -33,6 +35,12 @@ static inline struct tegra_dc_state *to_dc_state(struct drm_crtc_state *state)
 	return NULL;
 }
 
+static inline const struct tegra_dc_state *
+to_const_dc_state(const struct drm_crtc_state *state)
+{
+	return to_dc_state((struct drm_crtc_state *)state);
+}
+
 struct tegra_dc_stats {
 	unsigned long frames;
 	unsigned long vblank;
@@ -66,7 +74,9 @@ struct tegra_dc_soc_info {
 	unsigned int num_overlay_formats;
 	const u64 *modifiers;
 	bool has_win_a_without_filters;
+	bool has_win_b_vfilter_mem_client;
 	bool has_win_c_without_vert_filter;
+	bool plane_tiled_memory_bandwidth_x2;
 };
 
 struct tegra_dc {
@@ -152,6 +162,8 @@ int tegra_dc_state_setup_clock(struct tegra_dc *dc,
 			       struct drm_crtc_state *crtc_state,
 			       struct clk *clk, unsigned long pclk,
 			       unsigned int div);
+void tegra_crtc_atomic_post_commit(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state);
 
 /* from rgb.c */
 int tegra_dc_rgb_probe(struct tegra_dc *dc);
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index c850991241e8..ca1f66fd8d63 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -25,6 +25,7 @@
 #include <asm/dma-iommu.h>
 #endif
 
+#include "dc.h"
 #include "drm.h"
 #include "gem.h"
 
@@ -64,6 +65,17 @@ static const struct drm_mode_config_funcs tegra_drm_mode_config_funcs = {
 	.atomic_commit = drm_atomic_helper_commit,
 };
 
+static void tegra_atomic_post_commit(struct drm_device *drm,
+				     struct drm_atomic_state *old_state)
+{
+	struct drm_crtc_state *old_crtc_state __maybe_unused;
+	struct drm_crtc *crtc;
+	unsigned int i;
+
+	for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i)
+		tegra_crtc_atomic_post_commit(crtc, old_state);
+}
+
 static void tegra_atomic_commit_tail(struct drm_atomic_state *old_state)
 {
 	struct drm_device *drm = old_state->dev;
@@ -83,6 +95,8 @@ static void tegra_atomic_commit_tail(struct drm_atomic_state *old_state)
 	} else {
 		drm_atomic_helper_commit_tail_rpm(old_state);
 	}
+
+	tegra_atomic_post_commit(drm, old_state);
 }
 
 static const struct drm_mode_config_helper_funcs
diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c
index 2e11b4b1f702..ad6f5fbec00c 100644
--- a/drivers/gpu/drm/tegra/plane.c
+++ b/drivers/gpu/drm/tegra/plane.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/iommu.h>
+#include <linux/interconnect.h>
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
@@ -64,6 +65,9 @@ tegra_plane_atomic_duplicate_state(struct drm_plane *plane)
 	copy->reflect_x = state->reflect_x;
 	copy->reflect_y = state->reflect_y;
 	copy->opaque = state->opaque;
+	copy->total_peak_memory_bandwidth = state->total_peak_memory_bandwidth;
+	copy->peak_memory_bandwidth = state->peak_memory_bandwidth;
+	copy->avg_memory_bandwidth = state->avg_memory_bandwidth;
 
 	for (i = 0; i < 2; i++)
 		copy->blending[i] = state->blending[i];
@@ -244,6 +248,78 @@ void tegra_plane_cleanup_fb(struct drm_plane *plane,
 		tegra_dc_unpin(dc, to_tegra_plane_state(state));
 }
 
+static int tegra_plane_calculate_memory_bandwidth(struct drm_plane_state *state)
+{
+	struct tegra_plane_state *tegra_state = to_tegra_plane_state(state);
+	unsigned int i, bpp, dst_w, dst_h, src_w, src_h, mul;
+	const struct tegra_dc_soc_info *soc;
+	const struct drm_format_info *fmt;
+	struct drm_crtc_state *crtc_state;
+	u64 avg_bandwidth, peak_bandwidth;
+
+	if (!state->visible)
+		return 0;
+
+	crtc_state = drm_atomic_get_new_crtc_state(state->state, state->crtc);
+	if (!crtc_state)
+		return -EINVAL;
+
+	src_w = drm_rect_width(&state->src) >> 16;
+	src_h = drm_rect_height(&state->src) >> 16;
+	dst_w = drm_rect_width(&state->dst);
+	dst_h = drm_rect_height(&state->dst);
+
+	fmt = state->fb->format;
+	soc = to_tegra_dc(state->crtc)->soc;
+
+	/*
+	 * Note that real memory bandwidth vary depending on format and
+	 * memory layout, we are not taking that into account because small
+	 * estimation error isn't important since bandwidth is rounded up
+	 * anyway.
+	 */
+	for (i = 0, bpp = 0; i < fmt->num_planes; i++) {
+		unsigned int bpp_plane = fmt->cpp[i] * 8;
+
+		/*
+		 * Sub-sampling is relevant for chroma planes only and vertical
+		 * readouts are not cached, hence only horizontal sub-sampling
+		 * matters.
+		 */
+		if (i > 0)
+			bpp_plane /= fmt->hsub;
+
+		bpp += bpp_plane;
+	}
+
+	/* average bandwidth in kbytes/sec */
+	avg_bandwidth  = min(src_w, dst_w) * min(src_h, dst_h);
+	avg_bandwidth *= drm_mode_vrefresh(&crtc_state->adjusted_mode);
+	avg_bandwidth  = DIV_ROUND_UP(avg_bandwidth * bpp, 8) + 999;
+	do_div(avg_bandwidth, 1000);
+
+	/* mode.clock in kHz, peak bandwidth in kbytes/sec */
+	peak_bandwidth = DIV_ROUND_UP(crtc_state->adjusted_mode.clock * bpp, 8);
+
+	/*
+	 * Tegra30/114 Memory Controller can't interleave DC memory requests
+	 * for the tiled windows because DC uses 16-bytes atom, while DDR3
+	 * uses 32-bytes atom.  Hence there is x2 memory overfetch for tiled
+	 * framebuffer and DDR3 on these SoCs.
+	 */
+	if (soc->plane_tiled_memory_bandwidth_x2 &&
+	    tegra_state->tiling.mode == TEGRA_BO_TILING_MODE_TILED)
+		mul = 2;
+	else
+		mul = 1;
+
+	/* ICC bandwidth in kbytes/sec */
+	tegra_state->peak_memory_bandwidth = kBps_to_icc(peak_bandwidth) * mul;
+	tegra_state->avg_memory_bandwidth  = kBps_to_icc(avg_bandwidth)  * mul;
+
+	return 0;
+}
+
 int tegra_plane_state_add(struct tegra_plane *plane,
 			  struct drm_plane_state *state)
 {
@@ -262,6 +338,10 @@ int tegra_plane_state_add(struct tegra_plane *plane,
 	if (err < 0)
 		return err;
 
+	err = tegra_plane_calculate_memory_bandwidth(state);
+	if (err < 0)
+		return err;
+
 	tegra = to_dc_state(crtc_state);
 
 	tegra->planes |= WIN_A_ACT_REQ << plane->index;
@@ -627,3 +707,40 @@ int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
 
 	return 0;
 }
+
+static const char * const tegra_plane_icc_names[TEGRA_DC_LEGACY_PLANES_NUM] = {
+	"wina", "winb", "winc", NULL, NULL, NULL, "cursor",
+};
+
+int tegra_plane_interconnect_init(struct tegra_plane *plane)
+{
+	const char *icc_name = tegra_plane_icc_names[plane->index];
+	struct device *dev = plane->dc->dev;
+	struct tegra_dc *dc = plane->dc;
+	int err;
+
+	if (WARN_ON(plane->index >= TEGRA_DC_LEGACY_PLANES_NUM) ||
+	    WARN_ON(!tegra_plane_icc_names[plane->index]))
+		return -EINVAL;
+
+	plane->icc_mem = devm_of_icc_get(dev, icc_name);
+	err = PTR_ERR_OR_ZERO(plane->icc_mem);
+	if (err) {
+		dev_err_probe(dev, err, "failed to get %s interconnect\n",
+			      icc_name);
+		return err;
+	}
+
+	/* plane B on T20/30 has a dedicated memory client for a 6-tap vertical filter */
+	if (plane->index == 1 && dc->soc->has_win_b_vfilter_mem_client) {
+		plane->icc_mem_vfilter = devm_of_icc_get(dev, "winb-vfilter");
+		err = PTR_ERR_OR_ZERO(plane->icc_mem_vfilter);
+		if (err) {
+			dev_err_probe(dev, err, "failed to get %s interconnect\n",
+				      "winb-vfilter");
+			return err;
+		}
+	}
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/tegra/plane.h b/drivers/gpu/drm/tegra/plane.h
index c691dd79b27b..31ff7721e9a9 100644
--- a/drivers/gpu/drm/tegra/plane.h
+++ b/drivers/gpu/drm/tegra/plane.h
@@ -8,6 +8,7 @@
 
 #include <drm/drm_plane.h>
 
+struct icc_path;
 struct tegra_bo;
 struct tegra_dc;
 
@@ -16,6 +17,9 @@ struct tegra_plane {
 	struct tegra_dc *dc;
 	unsigned int offset;
 	unsigned int index;
+
+	struct icc_path *icc_mem;
+	struct icc_path *icc_mem_vfilter;
 };
 
 struct tegra_cursor {
@@ -52,6 +56,11 @@ struct tegra_plane_state {
 	/* used for legacy blending support only */
 	struct tegra_plane_legacy_blending_state blending[2];
 	bool opaque;
+
+	/* bandwidths are in ICC units, i.e. kbytes/sec */
+	u32 total_peak_memory_bandwidth;
+	u32 peak_memory_bandwidth;
+	u32 avg_memory_bandwidth;
 };
 
 static inline struct tegra_plane_state *
@@ -63,6 +72,12 @@ to_tegra_plane_state(struct drm_plane_state *state)
 	return NULL;
 }
 
+static inline const struct tegra_plane_state *
+to_const_tegra_plane_state(const struct drm_plane_state *state)
+{
+	return to_tegra_plane_state((struct drm_plane_state *)state);
+}
+
 extern const struct drm_plane_funcs tegra_plane_funcs;
 
 int tegra_plane_prepare_fb(struct drm_plane *plane,
@@ -77,5 +92,6 @@ int tegra_plane_format(u32 fourcc, u32 *format, u32 *swap);
 bool tegra_plane_format_is_yuv(unsigned int format, bool *planar);
 int tegra_plane_setup_legacy_state(struct tegra_plane *tegra,
 				   struct tegra_plane_state *state);
+int tegra_plane_interconnect_init(struct tegra_plane *plane);
 
 #endif /* TEGRA_PLANE_H */
-- 
2.30.2

[PATCH v18 2/2] drm/tegra: dc: Extend debug stats with total number of events

[Dmitry Osipenko]

It's useful to know the total number of underflow events and currently
the debug stats are getting reset each time CRTC is being disabled. Let's
account the overall number of events that doesn't get a reset.

Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/tegra/dc.c | 10 ++++++++++
 drivers/gpu/drm/tegra/dc.h |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 7dfe3250761f..173304f3467d 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1602,6 +1602,11 @@ static int tegra_dc_show_stats(struct seq_file *s, void *data)
 	seq_printf(s, "underflow: %lu\n", dc->stats.underflow);
 	seq_printf(s, "overflow: %lu\n", dc->stats.overflow);
 
+	seq_printf(s, "frames total: %lu\n", dc->stats.frames_total);
+	seq_printf(s, "vblank total: %lu\n", dc->stats.vblank_total);
+	seq_printf(s, "underflow total: %lu\n", dc->stats.underflow_total);
+	seq_printf(s, "overflow total: %lu\n", dc->stats.overflow_total);
+
 	return 0;
 }
 
@@ -2368,6 +2373,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): frame end\n", __func__);
 		*/
+		dc->stats.frames_total++;
 		dc->stats.frames++;
 	}
 
@@ -2376,6 +2382,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		dev_dbg(dc->dev, "%s(): vertical blank\n", __func__);
 		*/
 		drm_crtc_handle_vblank(&dc->base);
+		dc->stats.vblank_total++;
 		dc->stats.vblank++;
 	}
 
@@ -2383,6 +2390,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): underflow\n", __func__);
 		*/
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 
@@ -2390,11 +2398,13 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): overflow\n", __func__);
 		*/
+		dc->stats.overflow_total++;
 		dc->stats.overflow++;
 	}
 
 	if (status & HEAD_UF_INT) {
 		dev_dbg_ratelimited(dc->dev, "%s(): head underflow\n", __func__);
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 
diff --git a/drivers/gpu/drm/tegra/dc.h b/drivers/gpu/drm/tegra/dc.h
index 581263c7614a..dd171daace9e 100644
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -46,6 +46,11 @@ struct tegra_dc_stats {
 	unsigned long vblank;
 	unsigned long underflow;
 	unsigned long overflow;
+
+	unsigned long frames_total;
+	unsigned long vblank_total;
+	unsigned long underflow_total;
+	unsigned long overflow_total;
 };
 
 struct tegra_windowgroup_soc {
-- 
2.30.2

[PATCH v18 2/2] drm/tegra: dc: Extend debug stats with total number of events

[Dmitry Osipenko]

It's useful to know the total number of underflow events and currently
the debug stats are getting reset each time CRTC is being disabled. Let's
account the overall number of events that doesn't get a reset.

Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/gpu/drm/tegra/dc.c | 10 ++++++++++
 drivers/gpu/drm/tegra/dc.h |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 7dfe3250761f..173304f3467d 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1602,6 +1602,11 @@ static int tegra_dc_show_stats(struct seq_file *s, void *data)
 	seq_printf(s, "underflow: %lu\n", dc->stats.underflow);
 	seq_printf(s, "overflow: %lu\n", dc->stats.overflow);
 
+	seq_printf(s, "frames total: %lu\n", dc->stats.frames_total);
+	seq_printf(s, "vblank total: %lu\n", dc->stats.vblank_total);
+	seq_printf(s, "underflow total: %lu\n", dc->stats.underflow_total);
+	seq_printf(s, "overflow total: %lu\n", dc->stats.overflow_total);
+
 	return 0;
 }
 
@@ -2368,6 +2373,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): frame end\n", __func__);
 		*/
+		dc->stats.frames_total++;
 		dc->stats.frames++;
 	}
 
@@ -2376,6 +2382,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		dev_dbg(dc->dev, "%s(): vertical blank\n", __func__);
 		*/
 		drm_crtc_handle_vblank(&dc->base);
+		dc->stats.vblank_total++;
 		dc->stats.vblank++;
 	}
 
@@ -2383,6 +2390,7 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): underflow\n", __func__);
 		*/
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 
@@ -2390,11 +2398,13 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 		/*
 		dev_dbg(dc->dev, "%s(): overflow\n", __func__);
 		*/
+		dc->stats.overflow_total++;
 		dc->stats.overflow++;
 	}
 
 	if (status & HEAD_UF_INT) {
 		dev_dbg_ratelimited(dc->dev, "%s(): head underflow\n", __func__);
+		dc->stats.underflow_total++;
 		dc->stats.underflow++;
 	}
 
diff --git a/drivers/gpu/drm/tegra/dc.h b/drivers/gpu/drm/tegra/dc.h
index 581263c7614a..dd171daace9e 100644
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -46,6 +46,11 @@ struct tegra_dc_stats {
 	unsigned long vblank;
 	unsigned long underflow;
 	unsigned long overflow;
+
+	unsigned long frames_total;
+	unsigned long vblank_total;
+	unsigned long underflow_total;
+	unsigned long overflow_total;
 };
 
 struct tegra_windowgroup_soc {
-- 
2.30.2

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

01.06.2021 07:21, Dmitry Osipenko пишет:
> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
> which is done using interconnect framework. It fixes display corruption that
> happens due to insufficient memory bandwidth.
> 
> Changelog:
> 
> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>        dummy plane bandwidth state initialization from T186+ plane hub. This
>        was suggested by Thierry Reding to v17.
> 
>      - I haven't done anything about the cursor's plane bandwidth which
>        doesn't contribute to overlapping bandwidths for a small sized
>        window because it works okay as-is.

Thierry, will you take these patches for 5.14?

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

01.06.2021 07:21, Dmitry Osipenko пишет:
> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
> which is done using interconnect framework. It fixes display corruption that
> happens due to insufficient memory bandwidth.
> 
> Changelog:
> 
> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>        dummy plane bandwidth state initialization from T186+ plane hub. This
>        was suggested by Thierry Reding to v17.
> 
>      - I haven't done anything about the cursor's plane bandwidth which
>        doesn't contribute to overlapping bandwidths for a small sized
>        window because it works okay as-is.

Thierry, will you take these patches for 5.14?

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

07.06.2021 01:40, Dmitry Osipenko пишет:
> 01.06.2021 07:21, Dmitry Osipenko пишет:
>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>> which is done using interconnect framework. It fixes display corruption that
>> happens due to insufficient memory bandwidth.
>>
>> Changelog:
>>
>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>        was suggested by Thierry Reding to v17.
>>
>>      - I haven't done anything about the cursor's plane bandwidth which
>>        doesn't contribute to overlapping bandwidths for a small sized
>>        window because it works okay as-is.
> 
> Thierry, will you take these patches for 5.14?
> 

The display controller does _NOT_WORK_ properly without bandwidth
management. Can we get this patch into 5.14? What is the problem?

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

07.06.2021 01:40, Dmitry Osipenko пишет:
> 01.06.2021 07:21, Dmitry Osipenko пишет:
>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>> which is done using interconnect framework. It fixes display corruption that
>> happens due to insufficient memory bandwidth.
>>
>> Changelog:
>>
>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>        was suggested by Thierry Reding to v17.
>>
>>      - I haven't done anything about the cursor's plane bandwidth which
>>        doesn't contribute to overlapping bandwidths for a small sized
>>        window because it works okay as-is.
> 
> Thierry, will you take these patches for 5.14?
> 

The display controller does _NOT_WORK_ properly without bandwidth
management. Can we get this patch into 5.14? What is the problem?

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1479 bytes --]

On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
> 07.06.2021 01:40, Dmitry Osipenko пишет:
> > 01.06.2021 07:21, Dmitry Osipenko пишет:
> >> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
> >> which is done using interconnect framework. It fixes display corruption that
> >> happens due to insufficient memory bandwidth.
> >>
> >> Changelog:
> >>
> >> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
> >>        dummy plane bandwidth state initialization from T186+ plane hub. This
> >>        was suggested by Thierry Reding to v17.
> >>
> >>      - I haven't done anything about the cursor's plane bandwidth which
> >>        doesn't contribute to overlapping bandwidths for a small sized
> >>        window because it works okay as-is.
> > 
> > Thierry, will you take these patches for 5.14?
> > 
> 
> The display controller does _NOT_WORK_ properly without bandwidth
> management.

That's surprising. So either it has never worked before (which I think
I'd know) or something has caused this regression recently. In the
latter case we need to identify what that was and revert (or fix) it.

> Can we get this patch into 5.14? What is the problem?

There was not enough time to review and test this, so I didn't feel
comfortable picking it up so close to the -rc6 cut-off. I plan to pick
this up early in the v5.14 release cycle and target v5.15.

Thierry

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Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1479 bytes --]

On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
> 07.06.2021 01:40, Dmitry Osipenko пишет:
> > 01.06.2021 07:21, Dmitry Osipenko пишет:
> >> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
> >> which is done using interconnect framework. It fixes display corruption that
> >> happens due to insufficient memory bandwidth.
> >>
> >> Changelog:
> >>
> >> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
> >>        dummy plane bandwidth state initialization from T186+ plane hub. This
> >>        was suggested by Thierry Reding to v17.
> >>
> >>      - I haven't done anything about the cursor's plane bandwidth which
> >>        doesn't contribute to overlapping bandwidths for a small sized
> >>        window because it works okay as-is.
> > 
> > Thierry, will you take these patches for 5.14?
> > 
> 
> The display controller does _NOT_WORK_ properly without bandwidth
> management.

That's surprising. So either it has never worked before (which I think
I'd know) or something has caused this regression recently. In the
latter case we need to identify what that was and revert (or fix) it.

> Can we get this patch into 5.14? What is the problem?

There was not enough time to review and test this, so I didn't feel
comfortable picking it up so close to the -rc6 cut-off. I plan to pick
this up early in the v5.14 release cycle and target v5.15.

Thierry

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Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

21.06.2021 14:01, Thierry Reding пишет:
> On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
>> 07.06.2021 01:40, Dmitry Osipenko пишет:
>>> 01.06.2021 07:21, Dmitry Osipenko пишет:
>>>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>>>> which is done using interconnect framework. It fixes display corruption that
>>>> happens due to insufficient memory bandwidth.
>>>>
>>>> Changelog:
>>>>
>>>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>>>        was suggested by Thierry Reding to v17.
>>>>
>>>>      - I haven't done anything about the cursor's plane bandwidth which
>>>>        doesn't contribute to overlapping bandwidths for a small sized
>>>>        window because it works okay as-is.
>>>
>>> Thierry, will you take these patches for 5.14?
>>>
>>
>> The display controller does _NOT_WORK_ properly without bandwidth
>> management.
> 
> That's surprising. So either it has never worked before (which I think
> I'd know) or something has caused this regression recently. In the
> latter case we need to identify what that was and revert (or fix) it.

The problem is caused by the support of dynamic memory frequency scaling
which does a good job at keeping memory in a low power state during idle
time. So display controller may not get enough bandwidth at the start of
scanout if it won't request BW beforehand. This problem existed for many
years on T124 and now T20/30 are also affected. The DC of T20 is the
least tolerant to memory bandwidth troubles.

This problem is not critical, but it hurts user experience since high
resolution modes may not work at all and display output may become
distorted, requiring a DC reset.

>> Can we get this patch into 5.14? What is the problem?
> 
> There was not enough time to review and test this, so I didn't feel
> comfortable picking it up so close to the -rc6 cut-off. I plan to pick
> this up early in the v5.14 release cycle and target v5.15.

Thank you for the explanation! It's not uncommon to forget about
patches, so the silence worries me. I hoped that both the dynamic freq
scaling and display BW support would be merged around the same time, but
apparently we got a disconnect here.

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

21.06.2021 14:01, Thierry Reding пишет:
> On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
>> 07.06.2021 01:40, Dmitry Osipenko пишет:
>>> 01.06.2021 07:21, Dmitry Osipenko пишет:
>>>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>>>> which is done using interconnect framework. It fixes display corruption that
>>>> happens due to insufficient memory bandwidth.
>>>>
>>>> Changelog:
>>>>
>>>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>>>        was suggested by Thierry Reding to v17.
>>>>
>>>>      - I haven't done anything about the cursor's plane bandwidth which
>>>>        doesn't contribute to overlapping bandwidths for a small sized
>>>>        window because it works okay as-is.
>>>
>>> Thierry, will you take these patches for 5.14?
>>>
>>
>> The display controller does _NOT_WORK_ properly without bandwidth
>> management.
> 
> That's surprising. So either it has never worked before (which I think
> I'd know) or something has caused this regression recently. In the
> latter case we need to identify what that was and revert (or fix) it.

The problem is caused by the support of dynamic memory frequency scaling
which does a good job at keeping memory in a low power state during idle
time. So display controller may not get enough bandwidth at the start of
scanout if it won't request BW beforehand. This problem existed for many
years on T124 and now T20/30 are also affected. The DC of T20 is the
least tolerant to memory bandwidth troubles.

This problem is not critical, but it hurts user experience since high
resolution modes may not work at all and display output may become
distorted, requiring a DC reset.

>> Can we get this patch into 5.14? What is the problem?
> 
> There was not enough time to review and test this, so I didn't feel
> comfortable picking it up so close to the -rc6 cut-off. I plan to pick
> this up early in the v5.14 release cycle and target v5.15.

Thank you for the explanation! It's not uncommon to forget about
patches, so the silence worries me. I hoped that both the dynamic freq
scaling and display BW support would be merged around the same time, but
apparently we got a disconnect here.

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

21.06.2021 14:43, Dmitry Osipenko пишет:
> 21.06.2021 14:01, Thierry Reding пишет:
>> On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
>>> 07.06.2021 01:40, Dmitry Osipenko пишет:
>>>> 01.06.2021 07:21, Dmitry Osipenko пишет:
>>>>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>>>>> which is done using interconnect framework. It fixes display corruption that
>>>>> happens due to insufficient memory bandwidth.
>>>>>
>>>>> Changelog:
>>>>>
>>>>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>>>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>>>>        was suggested by Thierry Reding to v17.
>>>>>
>>>>>      - I haven't done anything about the cursor's plane bandwidth which
>>>>>        doesn't contribute to overlapping bandwidths for a small sized
>>>>>        window because it works okay as-is.
>>>>
>>>> Thierry, will you take these patches for 5.14?
>>>>
>>>
>>> The display controller does _NOT_WORK_ properly without bandwidth
>>> management.
>>
>> That's surprising. So either it has never worked before (which I think
>> I'd know) or something has caused this regression recently. In the
>> latter case we need to identify what that was and revert (or fix) it.
> 
> The problem is caused by the support of dynamic memory frequency scaling
> which does a good job at keeping memory in a low power state during idle
> time. So display controller may not get enough bandwidth at the start of
> scanout if it won't request BW beforehand. This problem existed for many
> years on T124 and now T20/30 are also affected. The DC of T20 is the
> least tolerant to memory bandwidth troubles.
> 
> This problem is not critical, but it hurts user experience since high
> resolution modes may not work at all and display output may become
> distorted, requiring a DC reset.
> 
>>> Can we get this patch into 5.14? What is the problem?
>>
>> There was not enough time to review and test this, so I didn't feel
>> comfortable picking it up so close to the -rc6 cut-off. I plan to pick
>> this up early in the v5.14 release cycle and target v5.15.
> 
> Thank you for the explanation! It's not uncommon to forget about
> patches, so the silence worries me. I hoped that both the dynamic freq
> scaling and display BW support would be merged around the same time, but
> apparently we got a disconnect here.
> 

Reminder ping :)

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

21.06.2021 14:43, Dmitry Osipenko пишет:
> 21.06.2021 14:01, Thierry Reding пишет:
>> On Mon, Jun 21, 2021 at 07:19:15AM +0300, Dmitry Osipenko wrote:
>>> 07.06.2021 01:40, Dmitry Osipenko пишет:
>>>> 01.06.2021 07:21, Dmitry Osipenko пишет:
>>>>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>>>>> which is done using interconnect framework. It fixes display corruption that
>>>>> happens due to insufficient memory bandwidth.
>>>>>
>>>>> Changelog:
>>>>>
>>>>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>>>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>>>>        was suggested by Thierry Reding to v17.
>>>>>
>>>>>      - I haven't done anything about the cursor's plane bandwidth which
>>>>>        doesn't contribute to overlapping bandwidths for a small sized
>>>>>        window because it works okay as-is.
>>>>
>>>> Thierry, will you take these patches for 5.14?
>>>>
>>>
>>> The display controller does _NOT_WORK_ properly without bandwidth
>>> management.
>>
>> That's surprising. So either it has never worked before (which I think
>> I'd know) or something has caused this regression recently. In the
>> latter case we need to identify what that was and revert (or fix) it.
> 
> The problem is caused by the support of dynamic memory frequency scaling
> which does a good job at keeping memory in a low power state during idle
> time. So display controller may not get enough bandwidth at the start of
> scanout if it won't request BW beforehand. This problem existed for many
> years on T124 and now T20/30 are also affected. The DC of T20 is the
> least tolerant to memory bandwidth troubles.
> 
> This problem is not critical, but it hurts user experience since high
> resolution modes may not work at all and display output may become
> distorted, requiring a DC reset.
> 
>>> Can we get this patch into 5.14? What is the problem?
>>
>> There was not enough time to review and test this, so I didn't feel
>> comfortable picking it up so close to the -rc6 cut-off. I plan to pick
>> this up early in the v5.14 release cycle and target v5.15.
> 
> Thank you for the explanation! It's not uncommon to forget about
> patches, so the silence worries me. I hoped that both the dynamic freq
> scaling and display BW support would be merged around the same time, but
> apparently we got a disconnect here.
> 

Reminder ping :)

Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 985 bytes --]

On Mon, Jun 07, 2021 at 01:40:06AM +0300, Dmitry Osipenko wrote:
> 01.06.2021 07:21, Dmitry Osipenko пишет:
> > This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
> > which is done using interconnect framework. It fixes display corruption that
> > happens due to insufficient memory bandwidth.
> > 
> > Changelog:
> > 
> > v18: - Moved total peak bandwidth from CRTC state to plane state and removed
> >        dummy plane bandwidth state initialization from T186+ plane hub. This
> >        was suggested by Thierry Reding to v17.
> > 
> >      - I haven't done anything about the cursor's plane bandwidth which
> >        doesn't contribute to overlapping bandwidths for a small sized
> >        window because it works okay as-is.
> 
> Thierry, will you take these patches for 5.14?

As discussed offline, I've picked these up for v5.15 with a small patch
squashed in to unbreak the Tegra186 and later support.

Thanks,
Thierry

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Re: [PATCH v18 0/2] Add memory bandwidth management to NVIDIA Tegra DRM driver

[Dmitry Osipenko]

13.08.2021 13:33, Thierry Reding пишет:
> On Mon, Jun 07, 2021 at 01:40:06AM +0300, Dmitry Osipenko wrote:
>> 01.06.2021 07:21, Dmitry Osipenko пишет:
>>> This series adds memory bandwidth management to the NVIDIA Tegra DRM driver,
>>> which is done using interconnect framework. It fixes display corruption that
>>> happens due to insufficient memory bandwidth.
>>>
>>> Changelog:
>>>
>>> v18: - Moved total peak bandwidth from CRTC state to plane state and removed
>>>        dummy plane bandwidth state initialization from T186+ plane hub. This
>>>        was suggested by Thierry Reding to v17.
>>>
>>>      - I haven't done anything about the cursor's plane bandwidth which
>>>        doesn't contribute to overlapping bandwidths for a small sized
>>>        window because it works okay as-is.
>>
>> Thierry, will you take these patches for 5.14?
> 
> As discussed offline, I've picked these up for v5.15 with a small patch
> squashed in to unbreak the Tegra186 and later support.

Cool, thanks.