drm/i915: Add a more detailed comment about the set_base() fastboot hack
Instead of it just being on the mailing list, let's put Jesse's
explanation next to the code in question.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 214984c..fe86325 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2320,7 +2320,19 @@
return ret;
}
- /* Update pipe size and adjust fitter if needed */
+ /*
+ * Update pipe size and adjust fitter if needed: the reason for this is
+ * that in compute_mode_changes we check the native mode (not the pfit
+ * mode) to see if we can flip rather than do a full mode set. In the
+ * fastboot case, we'll flip, but if we don't update the pipesrc and
+ * pfit state, we'll end up with a big fb scanned out into the wrong
+ * sized surface.
+ *
+ * To fix this properly, we need to hoist the checks up into
+ * compute_mode_changes (or above), check the actual pfit state and
+ * whether the platform allows pfit disable with pipe active, and only
+ * then update the pipesrc and pfit state, even on the flip path.
+ */
if (i915_fastboot) {
I915_WRITE(PIPESRC(intel_crtc->pipe),
((crtc->mode.hdisplay - 1) << 16) |