934aef885f
Trigger hotplug event with drm_kms_helper_hotplug_event might fail if the connector state pointer is NULL. BUG observed in exynos dsi driver where drm_bridge_attach is trying to register a connector in panel_bridge before the hotplug event is triggered. WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_atomic_state_helper.c:494 drm_atomic_helper_connector_duplicate_state+0x94/0x9c Modules linked in: CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.16.0-rc1-00009-g704b1dbfa4c2 #11058 Hardware name: Samsung Exynos (Flattened Device Tree) [<c0110b30>] (unwind_backtrace) from [<c010c618>] (show_stack+0x10/0x14) [<c010c618>] (show_stack) from [<c0b657d4>] (dump_stack_lvl+0x58/0x70) [<c0b657d4>] (dump_stack_lvl) from [<c01261dc>] (__warn+0xd0/0x134) [<c01261dc>] (__warn) from [<c0b5f628>] (warn_slowpath_fmt+0x5c/0xb4) [<c0b5f628>] (warn_slowpath_fmt) from [<c064bce4>] (drm_atomic_helper_connector_duplicate_state+0x94/0x9c) [<c064bce4>] (drm_atomic_helper_connector_duplicate_state) from [<c0666b64>] (drm_atomic_get_connector_state+0xd4/0x190) [<c0666b64>] (drm_atomic_get_connector_state) from [<c0667928>] (__drm_atomic_helper_set_config+0x314/0x368) [<c0667928>] (__drm_atomic_helper_set_config) from [<c067e628>] (drm_client_modeset_commit_atomic+0x170/0x278) [<c067e628>] (drm_client_modeset_commit_atomic) from [<c067e800>] (drm_client_modeset_commit_locked+0x60/0x1c8) [<c067e800>] (drm_client_modeset_commit_locked) from [<c067e98c>] (drm_client_modeset_commit+0x24/0x40) [<c067e98c>] (drm_client_modeset_commit) from [<c06509c0>] (drm_fb_helper_set_par+0xb8/0xf8) [<c06509c0>] (drm_fb_helper_set_par) from [<c05b86d0>] (fbcon_init+0x2c0/0x518) [<c05b86d0>] (fbcon_init) from [<c060636c>] (visual_init+0xc0/0x108) [<c060636c>] (visual_init) from [<c06085e4>] (do_bind_con_driver+0x1b8/0x3a4) [<c06085e4>] (do_bind_con_driver) from [<c0608b40>] (do_take_over_console+0x13c/0x1e8) [<c0608b40>] (do_take_over_console) from [<c05b6854>] (do_fbcon_takeover+0x78/0xd8) [<c05b6854>] (do_fbcon_takeover) from [<c05b1154>] (register_framebuffer+0x208/0x2e0) [<c05b1154>] (register_framebuffer) from [<c064ead0>] (__drm_fb_helper_initial_config_and_unlock+0x400/0x63c) [<c064ead0>] (__drm_fb_helper_initial_config_and_unlock) from [<c063a718>] (drm_kms_helper_hotplug_event+0x24/0x30) [<c063a718>] (drm_kms_helper_hotplug_event) from [<c068f668>] (exynos_dsi_host_attach+0x174/0x1fc) [<c068f668>] (exynos_dsi_host_attach) from [<c0699354>] (s6e8aa0_probe+0x1b4/0x218) So reset the atomic state for a given connector by freeing the state pointer and allocate a new empty state object. This can be done using connector funcs->reset helper and has to be done before the hotplug even calls. This patch calls the connector->funcs->reset in panel_bridge_attach. Signed-off-by: Jagan Teki <jagan@amarulasolutions.com> Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Robert Foss <robert.foss@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20220303163654.3381470-3-jagan@amarulasolutions.com
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.