From: Damien Lespiau Date: Mon, 30 Sep 2013 13:21:49 +0000 (+0100) Subject: drm/i915: Add a more detailed comment about the set_base() fastboot hack X-Git-Tag: firefly_0821_release~176^2~4694^2~167^2~2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=bb2043de02ef15901c2a1e6f9349c989dce42615;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 214984c814e8..fe863255dedc 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -2320,7 +2320,19 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y, 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) |