2bcd3ecab7
Since Linux 4.17, calls to drm_crtc_vblank_on/off are mandatory, and we get a warning when ctrc is disabled : " driver forgot to call drm_crtc_vblank_off()" But, the vsync IRQ was not totally disabled due the transient hardware state and specific interrupt line, thus adding proper IRQ masking from the HHI system control registers. The last change fixes a race condition introduced by calling the added drm_crtc_vblank_on/off when an HPD event occurs from the HDMI connector, triggering a WARN_ON() in the _atomic_begin() callback when the CRTC is disabled, thus also triggering a WARN_ON() in drm_vblank_put() : WARNING: CPU: 0 PID: 1185 at drivers/gpu/drm/meson/meson_crtc.c:157 meson_crtc_atomic_begin+0x78/0x80 [...] Call trace: meson_crtc_atomic_begin+0x78/0x80 drm_atomic_helper_commit_planes+0x140/0x218 drm_atomic_helper_commit_tail+0x38/0x80 commit_tail+0x7c/0x80 drm_atomic_helper_commit+0xdc/0x150 drm_atomic_commit+0x54/0x60 restore_fbdev_mode_atomic+0x198/0x238 restore_fbdev_mode+0x6c/0x1c0 drm_fb_helper_restore_fbdev_mode_unlocked+0x7c/0xf0 drm_fb_helper_set_par+0x34/0x60 drm_fb_helper_hotplug_event.part.28+0xb8/0xc8 drm_fbdev_client_hotplug+0xa4/0xe0 drm_client_dev_hotplug+0x90/0xe0 drm_kms_helper_hotplug_event+0x3c/0x48 drm_helper_hpd_irq_event+0x134/0x168 dw_hdmi_top_thread_irq+0x3c/0x50 [...] WARNING: CPU: 0 PID: 1185 at drivers/gpu/drm/drm_vblank.c:1026 drm_vblank_put+0xb4/0xc8 [...] Call trace: drm_vblank_put+0xb4/0xc8 drm_crtc_vblank_put+0x24/0x30 drm_atomic_helper_wait_for_vblanks.part.9+0x130/0x2b8 drm_atomic_helper_commit_tail+0x68/0x80 [...] The issue is that vblank need to be enabled in any occurrence of : - atomic_enable() - atomic_begin() and state->enable == true, which was not the case Moving the CRTC enable code to a common function and calling in one of these occurrence solves this race condition and makes sure vblank is enabled in each call to _atomic_begin() from the HPD event leading to drm_atomic_helper_commit_planes(). To Summarize : - Make sure that the CRTC code will call the drm_crtc_vblank_on()/off() - *Really* mask the Vsync IRQ - Initialize and enable vblank at the first atomic_begin()/_atomic_enable() Cc: stable@vger.kernel.org # 4.17+ Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Reviewed-by: Lyude Paul <lyude@redhat.com> [fixed typos+added cc for stable] Signed-off-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20181122160103.10993-1-narmstrong@baylibre.com Signed-off-by: Sean Paul <seanpaul@chromium.org> |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.