From: "Kumar, Mahesh" <mahesh1.ku...@intel.com>

 If the arbitary display bandwidth is > 60% of memory bandwith, for
 x-tile we should increase latency at all levels by 15us.

 If the arbitary dsplay bandwidth is greater than 20% of memory bandwith
 in case of y-tile  being enabled, double the scan lines

v2: Update the commit message to explain the WA (shobhit)

v3: - Address Damien's comment, use DIV_ROUND_UP_ULL macro
    - Check both mem_speed and mem_channel to be valid before applying
      WA(shobhit)

Signed-off-by: Shobhit Kumar <shobhit.ku...@intel.com>
Signed-off-by: Kumar, Mahesh <mahesh1.ku...@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.ku...@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |  9 ++++
 drivers/gpu/drm/i915/intel_pm.c | 92 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b040e7a..450e6d3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1624,6 +1624,12 @@ enum intel_pipe_crc_source {
        INTEL_PIPE_CRC_SOURCE_MAX,
 };
 
+enum watermark_memory_wa {
+       WATERMARK_WA_NONE,
+       WATERMARK_WA_X_TILED,
+       WATERMARK_WA_Y_TILED,
+};
+
 struct intel_pipe_crc_entry {
        uint32_t frame;
        uint32_t crc[5];
@@ -1926,6 +1932,9 @@ struct drm_i915_private {
                /* Committed wm config */
                struct intel_wm_config config;
 
+               /* This stores if WaterMark memory workaround is needed */
+               enum watermark_memory_wa mem_wa;
+
                /*
                 * The skl_wm_values structure is a bit too big for stack
                 * allocation, so we keep the staging struct where we store
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index a9f9396..da5ff34 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3225,6 +3225,11 @@ static bool skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
        if (latency == 0 || !cstate->base.active || !intel_pstate->visible)
                return false;
 
+       if (dev_priv->wm.mem_wa != WATERMARK_WA_NONE) {
+               if (fb->modifier[0] == I915_FORMAT_MOD_X_TILED)
+                       latency += 15;
+       }
+
        width = drm_rect_width(&intel_pstate->src) >> 16;
        height = drm_rect_height(&intel_pstate->src) >> 16;
 
@@ -3265,6 +3270,9 @@ static bool skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
                                WARN(1, "Unsupported pixel depth for rotation");
                        }
                }
+               if (dev_priv->wm.mem_wa == WATERMARK_WA_Y_TILED)
+                       min_scanlines *= 2;
+
                y_tile_minimum = plane_blocks_per_line * min_scanlines;
                selected_result = max(method2, y_tile_minimum);
        } else {
@@ -3715,6 +3723,89 @@ static void skl_set_plane_pixel_rate(struct drm_crtc 
*crtc)
 
 }
 
+static void
+skl_set_display_memory_wa(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct intel_crtc *intel_crtc = NULL;
+       struct intel_plane *intel_plane = NULL;
+       uint32_t num_active_crtc = 0;
+       uint64_t max_pixel_rate_pipe = 0;
+       uint64_t display_bw = 0, available_bw = 0;
+       bool y_tile_enabled = false;
+       int memory_portion = 0;
+
+       /* Verify that we got proper memory information */
+       if (dev_priv->dmi.mem_channel == 0 || dev_priv->dmi.mem_speed == -1) {
+               dev_priv->wm.mem_wa = WATERMARK_WA_NONE;
+               return;
+       }
+
+       for_each_intel_crtc(dev, intel_crtc) {
+               uint64_t max_pixel_rate_plane = 0;
+               uint64_t pipe_bw;
+               uint32_t num_active_plane = 0;
+               const struct intel_crtc_state *cstate = NULL;
+
+               if (!intel_crtc->active)
+                       continue;
+               cstate = to_intel_crtc_state(intel_crtc->base.state);
+               num_active_crtc++;
+
+               for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
+                       struct drm_plane *plane = &intel_plane->base;
+                       struct drm_framebuffer *fb = plane->state->fb;
+                       uint64_t plane_bw, interm_bw = 10000000;
+
+                       if (fb == NULL)
+                               continue;
+                       if (plane->type == DRM_PLANE_TYPE_CURSOR)
+                               continue;
+                       num_active_plane++;
+
+                       if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED)
+                               y_tile_enabled = true;
+
+                       /*
+                        * planeBW = pixel_rate(MHz) * BPP * plane downscale
+                        *              amount * pipe downscale amount;
+                        *
+                        * skl_pipe_pixel_rate return adjusted value according
+                        * to downscaling  amount
+                        * pixel rate is in KHz & downscale factor is multiplied
+                        * by 1000, so devide by 1000*1000
+                        */
+                       interm_bw = skl_pipe_pixel_rate(cstate) *
+                               drm_format_plane_cpp(fb->pixel_format, 0) *
+                               skl_plane_downscale_amount(intel_plane);
+
+                       if (fb->pixel_format == DRM_FORMAT_NV12)
+                               interm_bw += skl_pipe_pixel_rate(cstate) *
+                               drm_format_plane_cpp(fb->pixel_format, 1) *
+                               skl_plane_downscale_amount(intel_plane);
+
+                       plane_bw = DIV_ROUND_UP(interm_bw, (uint64_t) (1000 *
+                                               1000));
+                       max_pixel_rate_plane = max(max_pixel_rate_plane,
+                                       plane_bw);
+               }
+               pipe_bw = max_pixel_rate_plane * num_active_plane;
+               max_pixel_rate_pipe = max(max_pixel_rate_pipe, pipe_bw);
+       }
+       display_bw = max_pixel_rate_pipe * num_active_crtc;
+
+       available_bw = dev_priv->dmi.mem_channel * dev_priv->dmi.mem_speed * 8;
+
+       memory_portion = DIV_ROUND_UP_ULL((display_bw * 100), available_bw);
+
+       if (y_tile_enabled && (memory_portion >= 20))
+               dev_priv->wm.mem_wa = WATERMARK_WA_Y_TILED;
+       else if (memory_portion >= 60)
+               dev_priv->wm.mem_wa = WATERMARK_WA_X_TILED;
+       else
+               dev_priv->wm.mem_wa = WATERMARK_WA_NONE;
+}
+
 static void skl_clear_wm(struct skl_wm_values *watermarks, enum pipe pipe)
 {
        watermarks->wm_linetime[pipe] = 0;
@@ -3752,6 +3843,7 @@ static void skl_update_wm(struct drm_crtc *crtc)
 
        /* Calculate plane pixel rate for each plane in advance */
        skl_set_plane_pixel_rate(crtc);
+       skl_set_display_memory_wa(dev);
 
        if (!skl_update_pipe_wm(crtc, &results->ddb, pipe_wm))
                return;
-- 
2.5.0

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