[v4,04/15] drm/bridge: tc358764: add drm_panel_bridge support

Thu Aug 27 11:39:06 UTC 2020

Hi Sam,

On 26.07.2020 22:33, Sam Ravnborg wrote:
> Prepare the tc358764 bridge driver for use in a chained setup by
> replacing direct use of drm_panel with drm_panel_bridge support.
>
> The bridge panel will use the connector type reported by the panel,
> where the connector for this driver hardcodes DRM_MODE_CONNECTOR_LVDS.
>
> The tc358764 did not any additional info the the connector so the
> connector creation is passed to the bridge panel driver.
>
> v3:
>    - Merge with patch to make connector creation optional to avoid
>      creating two connectors (Laurent)
>    - Pass connector creation to bridge panel, as this bridge driver
>      did not add any extra info to the connector.
>    - Set bridge.type to DRM_MODE_CONNECTOR_LVDS.
>
> v2:
>    - Use PTR_ERR_OR_ZERO() (kbuild test robot)
>
> Signed-off-by: Sam Ravnborg <sam at ravnborg.org>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Cc: kbuild test robot <lkp at intel.com>
> Cc: Andrzej Hajda <a.hajda at samsung.com>
> Cc: Neil Armstrong <narmstrong at baylibre.com>
> Cc: Jonas Karlman <jonas at kwiboo.se>
> Cc: Jernej Skrabec <jernej.skrabec at siol.net>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

I've noticed that this patch has been merged recently to linux-next. 
Sadly it causes regression on Samsung Exynos5250-based Arndale board.

It can be observed by the following warning during boot:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_atomic_state_helper.c:494 
drm_atomic_helper_connector_duplicate_state+0x60/0x68
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc2-00501-g1644127f83bc 
#1526
Hardware name: Samsung Exynos (Flattened Device Tree)
[<c011184c>] (unwind_backtrace) from [<c010d250>] (show_stack+0x10/0x14)
[<c010d250>] (show_stack) from [<c0517ce4>] (dump_stack+0xbc/0xe8)
[<c0517ce4>] (dump_stack) from [<c01270a8>] (__warn+0xf0/0x108)
[<c01270a8>] (__warn) from [<c0127170>] (warn_slowpath_fmt+0xb0/0xb8)
[<c0127170>] (warn_slowpath_fmt) from [<c05e81f0>] 
(drm_atomic_helper_connector_duplicate_state+0x60/0x68)
[<c05e81f0>] (drm_atomic_helper_connector_duplicate_state) from 
[<c06014b8>] (drm_atomic_get_connector_state+0xfc/0x184)
[<c06014b8>] (drm_atomic_get_connector_state) from [<c0602238>] 
(__drm_atomic_helper_set_config+0x2a0/0x368)
[<c0602238>] (__drm_atomic_helper_set_config) from [<c06183b8>] 
(drm_client_modeset_commit_atomic+0x180/0x284)
[<c06183b8>] (drm_client_modeset_commit_atomic) from [<c061859c>] 
(drm_client_modeset_commit_locked+0x64/0x1cc)
[<c061859c>] (drm_client_modeset_commit_locked) from [<c0618728>] 
(drm_client_modeset_commit+0x24/0x40)
[<c0618728>] (drm_client_modeset_commit) from [<c05eb6b4>] 
(drm_fb_helper_restore_fbdev_mode_unlocked+0x50/0x94)
[<c05eb6b4>] (drm_fb_helper_restore_fbdev_mode_unlocked) from 
[<c05eb728>] (drm_fb_helper_set_par+0x30/0x5c)
[<c05eb728>] (drm_fb_helper_set_par) from [<c055dedc>] 
(fbcon_init+0x5c8/0x65c)
[<c055dedc>] (fbcon_init) from [<c05a8530>] (visual_init+0xc0/0x108)
[<c05a8530>] (visual_init) from [<c05aaca4>] 
(do_bind_con_driver+0x180/0x39c)
[<c05aaca4>] (do_bind_con_driver) from [<c05ab244>] 
(do_take_over_console+0x140/0x1cc)
[<c05ab244>] (do_take_over_console) from [<c055ac04>] 
(do_fbcon_takeover+0x84/0xe0)
[<c055ac04>] (do_fbcon_takeover) from [<c0553820>] 
(register_framebuffer+0x1cc/0x2dc)
[<c0553820>] (register_framebuffer) from [<c05eb19c>] 
(__drm_fb_helper_initial_config_and_unlock+0x3f0/0x5e8)
[<c05eb19c>] (__drm_fb_helper_initial_config_and_unlock) from 
[<c05d941c>] (drm_kms_helper_hotplug_event+0x24/0x30)
[<c05d941c>] (drm_kms_helper_hotplug_event) from [<c0628f74>] 
(exynos_dsi_host_attach+0x184/0x2d8)
[<c0628f74>] (exynos_dsi_host_attach) from [<c0634120>] 
(tc358764_probe+0x13c/0x1ac)
[<c0634120>] (tc358764_probe) from [<c064cce4>] (really_probe+0x200/0x48c)
[<c064cce4>] (really_probe) from [<c064d0d8>] 
(driver_probe_device+0x78/0x1fc)
[<c064d0d8>] (driver_probe_device) from [<c064d4c0>] 
(device_driver_attach+0x58/0x60)
[<c064d4c0>] (device_driver_attach) from [<c064d5a4>] 
(__driver_attach+0xdc/0x174)
[<c064d5a4>] (__driver_attach) from [<c064aaf0>] 
(bus_for_each_dev+0x68/0xb4)
[<c064aaf0>] (bus_for_each_dev) from [<c064be24>] 
(bus_add_driver+0x158/0x214)
[<c064be24>] (bus_add_driver) from [<c064e478>] (driver_register+0x78/0x110)
[<c064e478>] (driver_register) from [<c0102378>] 
(do_one_initcall+0x8c/0x424)
[<c0102378>] (do_one_initcall) from [<c1001158>] 
(kernel_init_freeable+0x190/0x204)
[<c1001158>] (kernel_init_freeable) from [<c0ab835c>] 
(kernel_init+0x8/0x118)
[<c0ab835c>] (kernel_init) from [<c0100114>] (ret_from_fork+0x14/0x20)
Exception stack(0xee8ddfb0 to 0xee8ddff8)
dfa0:                                     00000000 00000000 00000000 
00000000
dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
00000000
dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
irq event stamp: 171647
hardirqs last  enabled at (171653): [<c019ec00>] vprintk_emit+0x2ac/0x2ec
hardirqs last disabled at (171658): [<c019eab8>] vprintk_emit+0x164/0x2ec
softirqs last  enabled at (171486): [<c010174c>] __do_softirq+0x50c/0x608
softirqs last disabled at (171473): [<c0130340>] irq_exit+0x168/0x16c
---[ end trace 33117a16f066466a ]---

Then calling modetest end with segmentation fault. I'm not able to check 
currently if there is anything on the display because of having only 
remote access to the board. If this is important I will try to ask 
someone to help checking at the board's display at the office.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland