Hi Linus, On Wednesday, November 15, 2023 6:00 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > 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.k/ > ernel.org%2Flkml%2FCAPDyKFr0XjrU_udKoUKQ_q8RWaUkyqL%2B8fV- > 7s1CTMqi7u3- > Rg%40mail.gmail.com%2FT%2F&data=05%7C01%7Cvictor.liu%40nxp.com%7 > Cd007e6260de84d50c92b08dbe55d10e5%7C686ea1d3bc2b4c6fa92cd99c5c3 > 01635%7C0%7C0%7C638355960110773397%7CUnknown%7CTWFpbGZsb3d8 > eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3 > D%7C3000%7C%7C%7C&sdata=eXtezc2MPeFy1uo09iqHlYJq3iA6S%2BfxSre5y > s7xrhc%3D&reserved=0 > > 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 Sorry for the breakage and a bit late response(I'm a bit busy with internal things). I think device_link_add() fails because a0351000.dsi.0 already depends on a0350000.mcde. Can you confirm that device_link_add() returns NULL right after it calls device_is_dependent()? Does this patch fix the issue? --------------------------------------8<--------------------------------------------------- diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index e48823a4f1ed..d44de301a312 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -23,6 +23,7 @@ struct panel_bridge { struct drm_panel *panel; struct device_link *link; u32 connector_type; + bool is_independent; }; static inline struct panel_bridge * @@ -67,12 +68,17 @@ static int panel_bridge_attach(struct drm_bridge *bridge, struct drm_device *drm_dev = bridge->dev; int ret; - panel_bridge->link = device_link_add(drm_dev->dev, panel->dev, - DL_FLAG_STATELESS); - if (!panel_bridge->link) { - DRM_ERROR("Failed to add device link between %s and %s\n", - dev_name(drm_dev->dev), dev_name(panel->dev)); - return -EINVAL; + panel_bridge->is_independent = !device_is_dependent(drm_dev->dev, + panel->dev); + + if (panel_bridge->is_independent) { + panel_bridge->link = device_link_add(drm_dev->dev, panel->dev, + DL_FLAG_STATELESS); + if (!panel_bridge->link) { + DRM_ERROR("Failed to add device link between %s and %s\n", + dev_name(drm_dev->dev), dev_name(panel->dev)); + return -EINVAL; + } } if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) @@ -92,7 +98,8 @@ static int panel_bridge_attach(struct drm_bridge *bridge, panel_bridge->connector_type); if (ret) { DRM_ERROR("Failed to initialize connector\n"); - device_link_del(panel_bridge->link); + if (panel_bridge->is_independent) + device_link_del(panel_bridge->link); return ret; } @@ -115,7 +122,8 @@ static void panel_bridge_detach(struct drm_bridge *bridge) struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge); struct drm_connector *connector = &panel_bridge->connector; - device_link_del(panel_bridge->link); + if (panel_bridge->is_independent) + device_link_del(panel_bridge->link); /* * Cleanup the connector if we know it was initialized. --------------------------------------8<--------------------------------------------------- > [ 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. This indicates that the panel device already depends on the mcde device. Regards, Liu Ying > > Suggestions welcome, I'm clueless why this happens. > > Yours, > Linus Walleij
