linux-kernel - imx-drm: Possible regression after update to atomic

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date:	Sat, 13 Aug 2016 13:37:32 +0100
from:	"Peter Senna Tschudin" <peter.senna@...labora.co.uk>
to:	airlied@...ux.ie, linux-kernel@...r.kernel.org,
	peter.senna@...il.com, p.zabel@...gutronix.de,
	dri-devel@...ts.freedesktop.org, gnuiyl@...il.com
subject: imx-drm: Possible regression after update to atomic


d7868cb7ac58640e9c0383205ba31bd6a985cc6f is the last commit that works for me. I'm experiencing black screen after Weston starts in two different i.MX based devices:

 - i.MX6 -> arch/arm/boot/dts/imx6q-b850v3.dts
 - i.MX53 based device

Weston starts, but nothing is shown on screen. fb works fine. Disabling fb on Kconfig or simply commenting out drm_fbdev_cma_init() solves the black screen issue.

The tests that are causing the black screen:

diff --git a/drivers/gpu/drm/imx/ipuv3-plane.c b/drivers/gpu/drm/imx/ipuv3-plane.c
index 4ad67d0..52dc1b7 100644
--- a/drivers/gpu/drm/imx/ipuv3-plane.c
+++ b/drivers/gpu/drm/imx/ipuv3-plane.c
@@ -325,7 +325,7 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
        if (old_fb && (state->src_w != old_state->src_w ||
                              state->src_h != old_state->src_h ||
                              fb->pixel_format != old_fb->pixel_format))
-               return -EINVAL;
 
        eba = drm_plane_state_to_eba(state);
 
@@ -336,7 +336,7 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
                return -EINVAL;
 
        if (old_fb && fb->pitches[0] != old_fb->pitches[0])
-               return -EINVAL;
 
        switch (fb->pixel_format) {
        case DRM_FORMAT_YUV420:
@@ -372,7 +372,7 @@ static int ipu_plane_atomic_check(struct drm_plane *plane,
                        return -EINVAL;
 
                if (old_fb && old_fb->pitches[1] != fb->pitches[1])
-                       return -EINVAL;
        }

I tried to replace the return -EINVAL by crtc_state->mode_changed = true with no positive results.

I'm trying to understand what is the difference with and without fb, but I have no conclusions yet.

Hints on what could be the cause here?

Thank you,

Peter

P.S. This is what I get after replacing the return -EINVAL(the mode is correct): https://goo.gl/photos/1eRdcco9GpszgvzM8