On Mon, Aug 7, 2023 at 8:06 AM Liu Ying <victor.liu@xxxxxxx> wrote: > Add the device link when panel bridge is attached and delete the link > when panel bridge is detached. The drm device is the consumer while > the panel device is the supplier. This makes sure that the drm device > suspends eariler and resumes later than the panel device, hence resolves > problems where the order is reversed, like the problematic case mentioned > in the below link. > > Link: https://lore.kernel.org/lkml/CAPDyKFr0XjrU_udKoUKQ_q8RWaUkyqL+8fV-7s1CTMqi7u3-Rg@xxxxxxxxxxxxxx/T/ > Suggested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx> > --- > v2->v3: > * Improve commit message s/swapped/reversed/. This patch causes a regression in the Ux500 MCDE drivers/gpu/drm/mcde/* driver with the nt35510 panel drivers/gpu/drm/panel/panel-novatek-nt35510.c my dmesg looks like this: [ 1.678680] mcde a0350000.mcde: MCDE clk rate 199680000 Hz [ 1.684448] mcde a0350000.mcde: found MCDE HW revision 3.0 (dev 8, metal fix 0) [ 1.692840] mcde-dsi a0351000.dsi: HW revision 0x02327457 [ 1.699310] mcde-dsi a0351000.dsi: attached DSI device with 2 lanes [ 1.705627] mcde-dsi a0351000.dsi: format 00000000, 24bpp [ 1.711059] mcde-dsi a0351000.dsi: mode flags: 00000400 [ 1.716400] mcde-dsi a0351000.dsi: registered DSI host [ 1.722473] mcde-dsi a0352000.dsi: HW revision 0x02327457 [ 1.727874] mcde-dsi a0352000.dsi: registered DSI host [ 1.733734] mcde-dsi a0353000.dsi: HW revision 0x02327457 [ 1.739135] mcde-dsi a0353000.dsi: registered DSI host [ 1.814971] mcde-dsi a0351000.dsi: connected to panel [ 1.820037] mcde-dsi a0351000.dsi: initialized MCDE DSI bridge [ 1.825958] mcde a0350000.mcde: bound a0351000.dsi (ops mcde_dsi_component_ops) [ 1.833312] mcde-dsi a0352000.dsi: unused DSI interface [ 1.838531] mcde a0350000.mcde: bound a0352000.dsi (ops mcde_dsi_component_ops) [ 1.845886] mcde-dsi a0353000.dsi: unused DSI interface [ 1.851135] mcde a0350000.mcde: bound a0353000.dsi (ops mcde_dsi_component_ops) [ 1.858917] [drm:panel_bridge_attach] *ERROR* Failed to add device link between a0350000.mcde and a0351000.dsi.0 [ 1.869171] [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc/mcde@a0350000/dsi@a0351000/panel to encoder None-34: -22 [ 1.880920] [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc/mcde@a0350000/dsi@a0351000 to encoder None-34: -22 [ 1.892120] mcde a0350000.mcde: failed to attach display output bridge [ 1.898773] mcde a0350000.mcde: adev bind failed: -22 [ 1.903991] mcde a0350000.mcde: failed to add component master [ 1.909912] mcde: probe of a0350000.mcde failed with error -22 [ 1.916656] ------------[ cut here ]------------ [ 1.921295] WARNING: CPU: 1 PID: 1 at drivers/regulator/core.c:2996 _regulator_disable+0x130/0x190 [ 1.930297] unbalanced disables for AUX6 [ 1.934265] Modules linked in: [ 1.937347] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.6.0-08649-g7d461b291e65 #3 [ 1.944915] Hardware name: ST-Ericsson Ux5x0 platform (Device Tree Support) [ 1.951873] unwind_backtrace from show_stack+0x10/0x14 [ 1.957122] show_stack from dump_stack_lvl+0x40/0x4c [ 1.962188] dump_stack_lvl from __warn+0x84/0xc8 [ 1.966918] __warn from warn_slowpath_fmt+0x124/0x190 [ 1.972076] warn_slowpath_fmt from _regulator_disable+0x130/0x190 [ 1.978271] _regulator_disable from regulator_bulk_disable+0x5c/0x100 [ 1.984802] regulator_bulk_disable from nt35510_remove+0x1c/0x58 [ 1.990905] nt35510_remove from mipi_dsi_drv_remove+0x18/0x20 [ 1.996765] mipi_dsi_drv_remove from device_release_driver_internal+0x184/0x1f8 [ 2.004180] device_release_driver_internal from bus_remove_device+0xc0/0xe4 [ 2.011230] bus_remove_device from device_del+0x14c/0x464 [ 2.016723] device_del from device_unregister+0xc/0x20 [ 2.021972] device_unregister from mipi_dsi_remove_device_fn+0x34/0x3c [ 2.028594] mipi_dsi_remove_device_fn from device_for_each_child+0x64/0xa4 [ 2.035583] device_for_each_child from mipi_dsi_host_unregister+0x24/0x50 [ 2.042480] mipi_dsi_host_unregister from platform_remove+0x20/0x5c [ 2.048858] platform_remove from device_release_driver_internal+0x184/0x1f8 [ 2.055908] device_release_driver_internal from bus_remove_device+0xc0/0xe4 [ 2.062957] bus_remove_device from device_del+0x14c/0x464 [ 2.068450] device_del from platform_device_del.part.0+0x10/0x74 [ 2.074554] platform_device_del.part.0 from platform_device_unregister+0x18/0x24 [ 2.082061] platform_device_unregister from of_platform_device_destroy+0x9c/0xac [ 2.089569] of_platform_device_destroy from device_for_each_child_reverse+0x78/0xbc [ 2.097320] device_for_each_child_reverse from devm_of_platform_populate_release+0x34/0x48 [ 2.105682] devm_of_platform_populate_release from devres_release_all+0x94/0xf8 [ 2.113098] devres_release_all from device_unbind_cleanup+0xc/0x60 [ 2.119384] device_unbind_cleanup from really_probe+0x1a0/0x2d8 [ 2.125396] really_probe from __driver_probe_device+0x84/0xd4 [ 2.131225] __driver_probe_device from driver_probe_device+0x30/0x104 [ 2.137756] driver_probe_device from __driver_attach+0x90/0x178 [ 2.143768] __driver_attach from bus_for_each_dev+0x7c/0xcc [ 2.149444] bus_for_each_dev from bus_add_driver+0xcc/0x1cc [ 2.155120] bus_add_driver from driver_register+0x7c/0x114 [ 2.160705] driver_register from do_one_initcall+0x5c/0x190 [ 2.166381] do_one_initcall from kernel_init_freeable+0x1f8/0x250 [ 2.172576] kernel_init_freeable from kernel_init+0x18/0x12c [ 2.178344] kernel_init from ret_from_fork+0x14/0x28 [ 2.183410] Exception stack(0xf08c5fb0 to 0xf08c5ff8) [ 2.188446] 5fa0: 00000000 00000000 00000000 00000000 [ 2.196624] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 2.204803] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 2.211486] ---[ end trace 0000000000000000 ]--- [ 2.216125] Failed to disable vddi: -EIO [ 2.220062] panel-novatek-nt35510 a0351000.dsi.0: Failed to power off Reverting the patch solves the problem. See device tree at e.g.: arch/arm/boot/dts/st/ste-ux500-samsung-skomer.dts The usual problems with patches like this is that our DSI panel is attached in the DT without any graph: mcde@a0350000 { status = "okay"; pinctrl-names = "default"; pinctrl-0 = <&dsi_default_mode>; dsi@a0351000 { panel { /* NT35510-based Hydis HVA40WV1 */ compatible = "hydis,hva40wv1", "novatek,nt35510"; reg = <0>; /* v_lcd_3v0 2.3-4.8V */ vdd-supply = <&ab8500_ldo_aux4_reg>; /* v_lcd_1v8 1.65-3.3V */ vddi-supply = <&ab8500_ldo_aux6_reg>; /* GPIO 139 */ reset-gpios = <&gpio4 11 GPIO_ACTIVE_LOW>; pinctrl-names = "default"; pinctrl-0 = <&display_default_mode>; backlight = <&ktd253>; }; }; }; The DSI bridge is inside the display controller (MCDE) and the panel is right inside the DSI bridge. Suggestions welcome, I'm clueless why this happens. Yours, Linus Walleij
