On Fri, Nov 06, 2015 at 11:05:48AM +0100, Philipp Zabel wrote:
Am Mittwoch, den 04.11.2015, 18:15 +0800 schrieb Liu Ying:
Since we are using ipu_plane_init() to add one primary plane for each IPU CRTC, it's unnecessary to create the safe one by using the helper create_primary_plane().
Furthermore, the safe one is attached to crtc->primary, which actually carries a framebuffer(crtc->primary->fb) created by the fbdev helper to build up the fbcon. Instead, the one created by ipu_plane_init() is dangling, but it is the one actually does ipu_plane_mode_set() for the fbcon. This may causes the mismatch bewteen ipu_plane->enabled(true) and ipu_plane->base.fb(NULL). Thus, it brings a NULL pointer dereference issue in ipu_plane_mode_set() when we try to additionally touch the IDMAC channel of the ipu_plane. This issue could be reproduced by running the drm modetest with command line 'modetest -P 19:1024x768@XR24' on the i.MX6Q SabreSD platform(single LVDS display). This patch binds the plane created by ipu_plane_init() with crtc->primary and removes the safe one to address this issue.
Signed-off-by: Liu Ying Ying.Liu@freescale.com
drivers/gpu/drm/imx/imx-drm-core.c | 3 ++- drivers/gpu/drm/imx/ipuv3-crtc.c | 6 ++++++ 2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c index 6faa735..08eceeb 100644 --- a/drivers/gpu/drm/imx/imx-drm-core.c +++ b/drivers/gpu/drm/imx/imx-drm-core.c @@ -373,7 +373,8 @@ int imx_drm_add_crtc(struct drm_device *drm, struct drm_crtc *crtc, drm_crtc_helper_add(crtc, imx_drm_crtc->imx_drm_helper_funcs.crtc_helper_funcs);
- drm_crtc_init(drm, crtc,
- /* The related primary plane will be created in ipu_plane_init(). */
- drm_crtc_init_with_planes(drm, crtc, NULL, NULL, imx_drm_crtc->imx_drm_helper_funcs.crtc_funcs);
We rather should generate the plane first and add the primary_plane parameter to imx_drm_add_crtc than calling drm_crtc_init_with_planes without planes.
Yes, that is the regular way. I thought about that, though I took the easy approach here.
The question is that we currently generate the crtc pipe number in imx_drm_add_crtc() first, and then pass it to ipu_plane_init(). Do you think it would be good to add OF alias id for IPU, pass the id to ipu_crtc_init() via struct ipu_soc and determine the pipe number in ipu_crtc_init() by using the IPU id and pdata->di? This way, ipu_plane_init() may know the pipe number in the first place. Or, any other suggestions?
Regards, Liu Ying
regards Philipp