[PATCH 48/89 v6] drm/i915/skl: Allocate DDB portions for display planes

Damien Lespiau
2014-09-27T14:15:03Z

v2: Fix the 3rd plane/cursor logic (Pradeep Bhat)
v3: Fix one-by-one error in the DDB allocation code
v4: Rebase on top of the skl_pipe_pixel_rate() argument change
v5: Replace the available/start/end output parameters of
skl_ddb_get_pipe_allocation_limits() by a single ddb entry constify
a few arguments
Make nth_active_pipe 0 indexed
Use sizeof(variable) instead of sizeof(type)
(Ville)
v6: Use the for_each_crtc() macro instead of list_for_each_entry()

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
---
drivers/gpu/drm/i915/intel_pm.c | 148 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 148 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 1db4aa8..3dc689e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2965,6 +2965,153 @@ static bool ilk_disable_lp_wm(struct drm_device *dev)
return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
}

+/*
+ * On gen9, we need to allocate Display Data Buffer (DDB) portions to the
+ * different active planes.
+ */
+
+#define SKL_DDB_SIZE 896 /* in blocks */
+
+static void
+skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
+ struct drm_crtc *for_crtc,
+ const struct intel_wm_config *config,
+ const struct skl_pipe_wm_parameters *params,
+ struct skl_ddb_entry *alloc /* out */)
+{
+ struct drm_crtc *crtc;
+ unsigned int pipe_size, ddb_size;
+ int nth_active_pipe;
+
+ if (!params->active) {
+ alloc->start = 0;
+ alloc->end = 0;
+ return;
+ }
+
+ ddb_size = SKL_DDB_SIZE;
+
+ ddb_size -= 4; /* 4 blocks for bypass path allocation */
+
+ nth_active_pipe = 0;
+ for_each_crtc(dev, crtc) {
+ if (!intel_crtc_active(crtc))
+ continue;
+
+ if (crtc == for_crtc)
+ break;
+
+ nth_active_pipe++;
+ }
+
+ pipe_size = ddb_size / config->num_pipes_active;
+ alloc->start = nth_active_pipe * ddb_size / config->num_pipes_active;
+ alloc->end = alloc->start + pipe_size - 1;
+}
+
+static unsigned int skl_cursor_allocation(const struct intel_wm_config *config)
+{
+ if (config->num_pipes_active == 1)
+ return 32;
+
+ return 8;
+}
+
+static unsigned int
+skl_plane_relative_data_rate(const struct intel_plane_wm_parameters *p)
+{
+ return p->horiz_pixels * p->vert_pixels * p->bytes_per_pixel;
+}
+
+/*
+ * We don't overflow 32 bits. Worst case is 3 planes enabled, each fetching
+ * a 8192x4096@32bpp framebuffer:
+ * 3 * 4096 * 8192 * 4 < 2^32
+ */
+static unsigned int
+skl_get_total_relative_data_rate(struct intel_crtc *intel_crtc,
+ const struct skl_pipe_wm_parameters *params)
+{
+ unsigned int total_data_rate = 0;
+ int plane;
+
+ for (plane = 0; plane < intel_num_planes(intel_crtc); plane++) {
+ const struct intel_plane_wm_parameters *p;
+
+ p = &params->plane[plane];
+ if (!p->enabled)
+ continue;
+
+ total_data_rate += skl_plane_relative_data_rate(p);
+ }
+
+ return total_data_rate;
+}
+
+static void
+skl_allocate_pipe_ddb(struct drm_crtc *crtc,
+ const struct intel_wm_config *config,
+ const struct skl_pipe_wm_parameters *params,
+ struct skl_ddb_allocation *ddb /* out */)
+{
+ struct drm_device *dev = crtc->dev;
+ struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+ enum pipe pipe = intel_crtc->pipe;
+ struct skl_ddb_entry alloc;
+ uint16_t alloc_size, start, cursor_blocks;
+ unsigned int total_data_rate;
+ int plane;
+
+ skl_ddb_get_pipe_allocation_limits(dev, crtc, config, params, &alloc);
+ alloc_size = skl_ddb_entry_size(&alloc);
+ if (alloc_size == 0) {
+ memset(ddb->plane[pipe], 0, sizeof(ddb->plane[pipe]));
+ memset(&ddb->cursor[pipe], 0, sizeof(ddb->cursor[pipe]));
+ return;
+ }
+
+ cursor_blocks = skl_cursor_allocation(config);
+ ddb->cursor[pipe].start = alloc.end - cursor_blocks + 1;
+ ddb->cursor[pipe].end = alloc.end;
+
+ alloc_size -= cursor_blocks;
+ alloc.end -= cursor_blocks;
+
+ /*
+ * Each active plane get a portion of the remaining space, in
+ * proportion to the amount of data they need to fetch from memory.
+ *
+ * FIXME: we may not allocate every single block here.
+ */
+ total_data_rate = skl_get_total_relative_data_rate(intel_crtc, params);
+
+ start = alloc.start;
+ for (plane = 0; plane < intel_num_planes(intel_crtc); plane++) {
+ const struct intel_plane_wm_parameters *p;
+ unsigned int data_rate;
+ uint16_t plane_blocks;
+
+ p = &params->plane[plane];
+ if (!p->enabled)
+ continue;
+
+ data_rate = skl_plane_relative_data_rate(p);
+
+ /*
+ * promote the expression to 64 bits to avoid overflowing, the
+ * result is < available as data_rate / total_data_rate < 1
+ */
+ plane_blocks = div_u64((uint64_t)alloc_size * data_rate,
+ total_data_rate);
+
+ ddb->plane[pipe][plane].start = start;
+ ddb->plane[pipe][plane].end = start + plane_blocks - 1;
+
+ start += plane_blocks;
+ }
+
+}
+
static uint32_t skl_pipe_pixel_rate(const struct intel_crtc_config *config)
{
/* TODO: Take into account the scalers once we support them */
@@ -3286,6 +3433,7 @@ static bool skl_update_pipe_wm(struct drm_crtc *crtc,
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);

skl_compute_wm_pipe_parameters(crtc, params);
+ skl_allocate_pipe_ddb(crtc, config, params, ddb);
skl_compute_pipe_wm(crtc, ddb, params, pipe_wm);

if (!memcmp(&intel_crtc->wm.skl_active, pipe_wm, sizeof(*pipe_wm)))
--
1.8.3.1