On 2014년 09월 12일 18:27, Andrzej Hajda wrote:
On 09/12/2014 10:57 AM, Daniel Vetter wrote:
On Fri, Sep 12, 2014 at 05:34:50PM +0900, Inki Dae wrote:
Hi Andrzej,
On 2014년 09월 09일 22:16, Andrzej Hajda wrote:
Adding reference to framebuffer should be accompanied with removing reference to old framebuffer assigned to the plane. This patch removes following warning:
[ 95.038017] WARNING: CPU: 1 PID: 3067 at drivers/gpu/drm/drm_crtc.c:5115 drm_mode_config_cleanup+0x258/0x268() [ 95.048086] Modules linked in: [ 95.051430] CPU: 1 PID: 3067 Comm: bash Tainted: G W 3.16.0-11355-g7a6eca5-dirty #3015 [ 95.060058] [<c0013e90>] (unwind_backtrace) from [<c0011128>] (show_stack+0x10/0x14) [ 95.067766] [<c0011128>] (show_stack) from [<c04a5dc4>] (dump_stack+0x70/0xbc) [ 95.074953] [<c04a5dc4>] (dump_stack) from [<c0021784>] (warn_slowpath_common+0x64/0x88) [ 95.083005] [<c0021784>] (warn_slowpath_common) from [<c00217c4>] (warn_slowpath_null+0x1c/0x24) [ 95.091780] [<c00217c4>] (warn_slowpath_null) from [<c0275fa0>] (drm_mode_config_cleanup+0x258/0x268) [ 95.100983] [<c0275fa0>] (drm_mode_config_cleanup) from [<c0281724>] (exynos_drm_unload+0x38/0x50) [ 95.109915] [<c0281724>] (exynos_drm_unload) from [<c026e248>] (drm_dev_unregister+0x24/0x98) [ 95.118414] [<c026e248>] (drm_dev_unregister) from [<c026ecb0>] (drm_put_dev+0x28/0x64) [ 95.126412] [<c026ecb0>] (drm_put_dev) from [<c02947c4>] (take_down_master+0x24/0x44) [ 95.134218] [<c02947c4>] (take_down_master) from [<c0294870>] (component_del+0x8c/0xc8) [ 95.142201] [<c0294870>] (component_del) from [<c0286c10>] (exynos_dsi_remove+0x18/0x2c) [ 95.150294] [<c0286c10>] (exynos_dsi_remove) from [<c0299e04>] (platform_drv_remove+0x18/0x1c) [ 95.158872] [<c0299e04>] (platform_drv_remove) from [<c02987a4>] (__device_release_driver+0x70/0xc4) [ 95.167981] [<c02987a4>] (__device_release_driver) from [<c0298818>] (device_release_driver+0x20/0x2c) [ 95.177268] [<c0298818>] (device_release_driver) from [<c02979d0>] (unbind_store+0x5c/0x94) [ 95.185597] [<c02979d0>] (unbind_store) from [<c0297278>] (drv_attr_store+0x20/0x2c) [ 95.193323] [<c0297278>] (drv_attr_store) from [<c012aa90>] (sysfs_kf_write+0x4c/0x50) [ 95.201224] [<c012aa90>] (sysfs_kf_write) from [<c0129e94>] (kernfs_fop_write+0xc4/0x184) [ 95.209393] [<c0129e94>] (kernfs_fop_write) from [<c00d03ec>] (vfs_write+0xa0/0x1a8) [ 95.217111] [<c00d03ec>] (vfs_write) from [<c00d07f8>] (SyS_write+0x40/0x8c) [ 95.224146] [<c00d07f8>] (SyS_write) from [<c000e660>] (ret_fast_syscall+0x0/0x48)
Signed-off-by: Andrzej Hajda a.hajda@samsung.com
drivers/gpu/drm/exynos/exynos_drm_crtc.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c index b68e58f..bde19f4 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c @@ -145,10 +145,16 @@ exynos_drm_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode, if (ret) return ret;
/* we need to unreference current fb after replacing it with new one */
old_fb = plane->fb;
plane->crtc = crtc; plane->fb = crtc->primary->fb; drm_framebuffer_reference(plane->fb);
if (old_fb)
drm_framebuffer_unreference(old_fb);This time would be a good chance that we can consider drm flip queue to make sure that whole memory region to old_fb is scanned out completely before dropping a reference of old_fb. the reference of old_fb should be dropped at irq handler of each crtc devices, fimd and mixer.
Generally it's not a good idea to drop fb references from irq context, since if you actually drop the last reference it'll blow up: fb cleanup needs a bunch of mutexes.
I agree with that.
Also the drm core really should be taking care of this for you, you only need to grab references yourself for async flips if you want the buffer to survive a bit. crtc_mode_set has not need for this. I expect that the refcounting bug is somewhere else, at least from my experience chasing such issues in i915 ;-)
Hmm, maybe I miss something but I do not see the core grabbing fb reference on plane->fb update. On the other side drm_framebuffer_remove calls drm_plane_force_disable which drops plane->fb reference. I am not yet familiar with this code so maybe there is better solution.
If not I guess it would be better to move this code to exynos_plane_mode_set. At least it is done this way in omap and msm, in fact it seems better place
I cannot see it in msm. In case of msm, drm flip queue is used in mdp4/5_crtc_mode_set function. See update_fb function there.
for such things. What do you think?
Regards Andrzej
-Daniel
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