drm/i915: Always calculate 8xx WM values based on a 32-bpp framebuffer

The specs for gen2 say that the watermark values "should always be set
assuming a 32bpp display mode, even though the display mode may be 15 or
16 bpp."

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 11 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 8f1561616bfb..0cbc0e6402b4 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1468,9 +1468,12 @@ static void i9xx_update_wm(struct drm_device *dev)
         fifo_size = dev_priv->display.get_fifo_size(dev, 0);
         crtc = intel_get_crtc_for_plane(dev, 0);
         if (crtc->enabled && crtc->fb) {
+                int cpp = crtc->fb->bits_per_pixel / 8;
+                if (IS_GEN2(dev))
+                        cpp = 4;
+
                 planea_wm = intel_calculate_wm(crtc->mode.clock,
-                                               wm_info, fifo_size,
-                                               crtc->fb->bits_per_pixel / 8,
+                                               wm_info, fifo_size, cpp,
                                                latency_ns);
                 enabled = crtc;
         } else
@@ -1479,9 +1482,12 @@ static void i9xx_update_wm(struct drm_device *dev)
         fifo_size = dev_priv->display.get_fifo_size(dev, 1);
         crtc = intel_get_crtc_for_plane(dev, 1);
         if (crtc->enabled && crtc->fb) {
+                int cpp = crtc->fb->bits_per_pixel / 8;
+                if (IS_GEN2(dev))
+                        cpp = 4;
+
                 planeb_wm = intel_calculate_wm(crtc->mode.clock,
-                                               wm_info, fifo_size,
-                                               crtc->fb->bits_per_pixel / 8,
+                                               wm_info, fifo_size, cpp,
                                                latency_ns);
                 if (enabled == NULL)
                         enabled = crtc;
@@ -1571,8 +1577,7 @@ static void i830_update_wm(struct drm_device *dev)
 
         planea_wm = intel_calculate_wm(crtc->mode.clock, &i830_wm_info,
                                        dev_priv->display.get_fifo_size(dev, 0),
-                                       crtc->fb->bits_per_pixel / 8,
-                                       latency_ns);
+                                       4, latency_ns);
         fwater_lo = I915_READ(FW_BLC) & ~0xfff;
         fwater_lo |= (3<<8) | planea_wm;