kernel.git/drivers/gpu/drm/msm/msm_fbdev.c, branch linux-6.4.y

drm/client: Send hotplug event after registering a client

2023-07-23T11:53:50Z

commit 27655b9bb9f0d9c32b8de8bec649b676898c52d5 upstream. Generate a hotplug event after registering a client to allow the client to configure its display. Remove the hotplug calls from the existing clients for fbdev emulation. This change fixes a concurrency bug between registering a client and receiving events from the DRM core. The bug is present in the fbdev emulation of all drivers. The fbdev emulation currently generates a hotplug event before registering the client to the device. For each new output, the DRM core sends an additional hotplug event to each registered client. If the DRM core detects first output between sending the artificial hotplug and registering the device, the output's hotplug event gets lost. If this is the first output, the fbdev console display remains dark. This has been observed with amdgpu and fbdev-generic. Fix this by adding hotplug generation directly to the client's register helper drm_client_register(). Registering the client and receiving events are serialized by struct drm_device.clientlist_mutex. So an output is either configured by the initial hotplug event, or the client has already been registered. The bug was originally added in commit 6e3f17ee73f7 ("drm/fb-helper: generic: Call drm_client_add() after setup is done"), in which adding a client and receiving a hotplug event switched order. It was hidden, as most hardware and drivers have at least on static output configured. Other drivers didn't use the internal DRM client or still had struct drm_mode_config_funcs.output_poll_changed set. That callback handled hotplug events as well. After not setting the callback in amdgpu in commit 0e3172bac3f4 ("drm/amdgpu: Don't set struct drm_driver.output_poll_changed"), amdgpu did not show a framebuffer console if output events got lost. The bug got copy-pasted from fbdev-generic into the other fbdev emulation. Reported-by: Moritz Duge Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2649 Fixes: 6e3f17ee73f7 ("drm/fb-helper: generic: Call drm_client_add() after setup is done") Fixes: 8ab59da26bc0 ("drm/fb-helper: Move generic fbdev emulation into separate source file") Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers") Fixes: 63c381552f69 ("drm/armada: Implement fbdev emulation as in-kernel client") Fixes: 49953b70e7d3 ("drm/exynos: Implement fbdev emulation as in-kernel client") Fixes: 8f1aaccb04b7 ("drm/gma500: Implement client-based fbdev emulation") Fixes: 940b869c2f2f ("drm/msm: Implement fbdev emulation as in-kernel client") Fixes: 9e69bcd88e45 ("drm/omapdrm: Implement fbdev emulation as in-kernel client") Fixes: e317a69fe891 ("drm/radeon: Implement client-based fbdev emulation") Fixes: 71ec16f45ef8 ("drm/tegra: Implement fbdev emulation as in-kernel client") Fixes: 0e3172bac3f4 ("drm/amdgpu: Don't set struct drm_driver.output_poll_changed") Signed-off-by: Thomas Zimmermann Tested-by: Moritz Duge Tested-by: Torsten Krah Tested-by: Paul Schyska Cc: Daniel Vetter Cc: David Airlie Cc: Noralf Trønnes Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Javier Martinez Canillas Cc: Russell King Cc: Inki Dae Cc: Seung-Woo Kim Cc: Kyungmin Park Cc: Krzysztof Kozlowski Cc: Patrik Jakobsson Cc: Rob Clark Cc: Abhinav Kumar Cc: Dmitry Baryshkov Cc: Tomi Valkeinen Cc: Alex Deucher Cc: "Christian König" Cc: "Pan, Xinhui" Cc: Thierry Reding Cc: Mikko Perttunen Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org Cc: freedreno@lists.freedesktop.org Cc: amd-gfx@lists.freedesktop.org Cc: linux-tegra@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: # v5.2+ Reviewed-by: Javier Martinez Canillas Reviewed-by: Dmitry Baryshkov # msm Link: https://patchwork.freedesktop.org/patch/msgid/20230710091029.27503-1-tzimmermann@suse.de [ Dropped changes to drivers/gpu/drm/armada/armada_fbdev.c as 174c3c38e3a2 drm/armada: Initialize fbdev DRM client was introduced in 6.5-rc1 ] Signed-off-by: Mario Limonciello Signed-off-by: Greg Kroah-Hartman

drm/msm: Implement fbdev emulation as in-kernel client

2023-04-06T17:29:40Z

Move code from ad-hoc fbdev callbacks into DRM client functions and remove the old callbacks. The functions instruct the client to poll for changed output or restore the display. The DRM core calls both, the old callbacks and the new client helpers, from the same places. The new functions perform the same operation as before, so there's no change in functionality. Replace all code that initializes or releases fbdev emulation throughout the driver. Instead initialize the fbdev client by a single call to msm_fbdev_setup() after msm has registered its DRM device. As in most drivers, msm's fbdev emulation now acts like a regular DRM client. The fbdev client setup consists of the initial preparation and the hot-plugging of the display. The latter creates the fbdev device and sets up the fbdev framebuffer. The setup performs display hot-plugging once. If no display can be detected, DRM probe helpers re-run the detection on each hotplug event. A call to drm_dev_unregister() releases the client automatically. No further action is required within msm. If the fbdev framebuffer has been fully set up, struct fb_ops.fb_destroy implements the release. For partially initialized emulation, the fbdev client reverts the initial setup. v2: * handle fbdev module parameter correctly (kernel test robot) Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Tested-by: Dmitry Baryshkov # RB5 Patchwork: https://patchwork.freedesktop.org/patch/530560/ Link: https://lore.kernel.org/r/20230403124538.8497-9-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Initialize fbdev DRM client

2023-04-06T17:29:40Z

Initialize the fbdev client in the fbdev code with empty helper functions. Also clean up the client. The helpers will later implement various functionality of the DRM client. No functional changes. Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530557/ Link: https://lore.kernel.org/r/20230403124538.8497-8-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Move module parameter 'fbdev' to fbdev code

2023-04-06T17:29:40Z

Define the module's parameter 'fbdev' in fbdev code. No other code uses it. No functional changes, but simplifies the later conversion to struct drm_client. Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530555/ Link: https://lore.kernel.org/r/20230403124538.8497-7-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Remove fbdev from struct msm_drm_private

2023-04-06T17:29:40Z

The DRM device stores a pointer to the fbdev helper. Remove struct msm_drm_private.fbdev, which contains the same value. No functional changes. v2: * test for fb_helper->fb in debugfs code Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530559/ Link: https://lore.kernel.org/r/20230403124538.8497-6-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Remove struct msm_fbdev

2023-04-06T17:29:40Z

Remove struct msm_fbdev, which is an empty wrapper around struct drm_fb_helper. Use the latter directly. No functional changes. v2: * kfree fbdev helper instance on init errors (Dmitri) Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530554/ Link: https://lore.kernel.org/r/20230403124538.8497-5-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Remove fb from struct msm_fbdev

2023-04-06T17:29:40Z

Fbdev's struct fb_helper stores a pointer to the framebuffer. Remove struct msm_fbdev.fb, which contains thre same value. No functional changes. Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530552/ Link: https://lore.kernel.org/r/20230403124538.8497-4-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Clear aperture ownership outside of fbdev code

2023-04-06T17:29:40Z

Move aperture management out of the fbdev code. It is unrelated and needs to run even if fbdev support has been disabled. Call the helper at the top of msm_drm_init() to take over hardware from other drivers. v2: * bind all subdevices before acquiring device (Dmitri) Signed-off-by: Thomas Zimmermann Reviewed-by: Dmitry Baryshkov Patchwork: https://patchwork.freedesktop.org/patch/530553/ Link: https://lore.kernel.org/r/20230403124538.8497-3-tzimmermann@suse.de Signed-off-by: Dmitry Baryshkov

drm/msm: Fix possible uninitialized access in fbdev

2023-02-22T16:12:36Z

Do not run drm_fb_helper_unprepare() if fbdev allocation fails. Avoids access to an uninitialized pointer. Original bug report is at [1]. Reported-by: kernel test robot Signed-off-by: Thomas Zimmermann Fixes: 3fb1f62f80a1 ("drm/fb-helper: Remove drm_fb_helper_unprepare() from drm_fb_helper_fini()") Link: https://lore.kernel.org/oe-kbuild-all/202302220810.9dymwCQ8-lkp@intel.com/ # 1 Reviewed-by: Dmitry Baryshkov Link: https://patchwork.freedesktop.org/patch/msgid/20230222123712.5049-1-tzimmermann@suse.de

drm/fb-helper: Remove drm_fb_helper_unprepare() from drm_fb_helper_fini()

2023-02-21T12:26:18Z

Move drm_fb_helper_unprepare() from drm_fb_helper_fini() into the calling fbdev implementation. Avoids a possible stale mutex with generic fbdev code. As indicated by its name, drm_fb_helper_prepare() prepares struct drm_fb_helper before setting up the fbdev support with a call to drm_fb_helper_init(). In legacy fbdev emulation, this happens next to each other. If successful, drm_fb_helper_fini() later tear down the fbdev device and also unprepare via drm_fb_helper_unprepare(). Generic fbdev emulation prepares struct drm_fb_helper immediately after allocating the instance. It only calls drm_fb_helper_init() as part of processing a hotplug event. If the hotplug-handling fails, it runs drm_fb_helper_fini(). This unprepares the fb-helper instance and the next hotplug event runs on stale data. Solve this by moving drm_fb_helper_unprepare() from drm_fb_helper_fini() into the fbdev implementations. Call it right before freeing the fb-helper instance. Fixes: 643231b28380 ("drm/fbdev-generic: Minimize hotplug error handling") Cc: Thomas Zimmermann Cc: Javier Martinez Canillas Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: David Airlie Cc: Daniel Vetter Cc: dri-devel@lists.freedesktop.org Signed-off-by: Thomas Zimmermann Reviewed-by: Daniel Vetter Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20230216140620.17699-1-tzimmermann@suse.de