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.ha...@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. 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 ;-) -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
