Hi Martin,
On Tue, 2020-07-07 at 17:56 +0200, Martin Fuzzey wrote:
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.
Could this be just a panel getting confused because the pixel clock is disabled, or is there really an issue with the IPU? Have you tried just keeping clk_di_pixel enabled in ipu_di_disable(), but continuing to disable DI and DC?
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);
Just removing ipu_di_disable() leaks a clk_prepare_enable refcount on the di->clk_di_pixel clock.
Also this is followed by an ipu_dc_disable(), which should remove the DC module's clock if this is the only display. So the DC should be disabled anyway.
- }
- /*
- Planes must be disabled before DC clock is removed, as otherwise the
- attached IDMACs will be left in undefined state, possibly hanging
regards Philipp