When performing a modeset the atomic core calls ipu_crtc_atomic_disable() which switches off the DC and DI.
When we immediately restart as in the modeset case this sometimes leads to corruption at the bottom of the screen looking like a mirror image of the top.
The exact reason isn't understood but it seems timing related.
This was observed on i.MX6DL on a system that does 2 mode transitions on boot (fbcon->android boot animation->android homescreen) then no more during normal operation resulting in corruption about once every 10 boots that lasted for variable durations from a few seconds to several hours.
Dumping the buffers confirmed that they were correct in memory, just the display was wrong.
For tests the problem was reproduced systematically by forcing a full modeset every 10 frames even if when not required.
Leaving the DC and DI on if the CRTC is staying on fixes this.
Signed-off-by: Martin Fuzzey martin.fuzzey@flowbird.group --- drivers/gpu/drm/imx/ipuv3-crtc.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c index 63c0284..9137b64 100644 --- a/drivers/gpu/drm/imx/ipuv3-crtc.c +++ b/drivers/gpu/drm/imx/ipuv3-crtc.c @@ -84,8 +84,15 @@ static void ipu_crtc_atomic_disable(struct drm_crtc *crtc, struct ipu_crtc *ipu_crtc = to_ipu_crtc(crtc); struct ipu_soc *ipu = dev_get_drvdata(ipu_crtc->dev->parent);
- ipu_dc_disable_channel(ipu_crtc->dc); - ipu_di_disable(ipu_crtc->di); + /* + * If we are just doing a modeset don't disable dc/di as that + * sometimes leads to corruption at the bottom of the screen + */ + if (!crtc->state->active) { + ipu_dc_disable_channel(ipu_crtc->dc); + ipu_di_disable(ipu_crtc->di); + } + /* * Planes must be disabled before DC clock is removed, as otherwise the * attached IDMACs will be left in undefined state, possibly hanging