> Am 12.04.2023 um 10:50 schrieb Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>: > > Hi Tony, > > Thank you for the patch. > > On Wed, Apr 12, 2023 at 10:39:53AM +0300, Tony Lindgren wrote: >> We may not have dsi->dsidev initialized during probe, and that can >> lead into various dsi related warnings as omap_dsi_host_detach() gets >> called with dsi->dsidev set to NULL. >> >> The warnings can be "Fixed dependency cycle(s)" followed by a >> WARNING: CPU: 0 PID: 787 at drivers/gpu/drm/omapdrm/dss/dsi.c:4414. > > How can this happen ? I assume .detach() can't be called without a > priori successful call to .attach(), that that sets dsi->dsidev. I have a similar patch (not submitted because it looks like a workaround) in our LetuxOS kernel: https://git.goldelico.com/?p=letux-kernel.git;a=commitdiff;h=0656acb534439d4546b33826de62694e1df1b8ad There I had commented: dsi_init_output() called by dsi_probe() may fail. In that case mipi_dsi_host_unregister() is called which may call omap_dsi_host_detach() with uninitialized dsi->dsidev because omap_dsi_host_attach() was never called before. This happens if the panel driver asks for an EPROBE_DEFER. So let's suppress the WARN() in this special case. [ 7.416759] WARNING: CPU: 0 PID: 32 at drivers/gpu/drm/omapdrm/dss/dsi.c:4419 omap_dsi_host_detach+0x3c/0xbc [omapdrm] [ 7.436053] Modules linked in: ina2xx_adc snd_soc_ts3a227e bq2429x_charger bq27xxx_battery_i2c(+) bq27xxx_battery ina2xx tca8418_keypad as5013(+) omapdrm hci_uart cec palmas_pwrbutton btbcm bmp280_spi palmas_gpadc bluetooth usb3503 ecdh_generic bmc150_accel_i2c bmg160_i2c ecc bmc150_accel_core bmg160_core bmc150_magn_i2c bmp280_i2c bmc150_magn bno055 industrialio_triggered_buffer bmp280 kfifo_buf snd_soc_omap_aess display_connector drm_kms_helper syscopyarea snd_soc_omap_mcbsp snd_soc_ti_sdma sysfillrect ti_tpd12s015 sysimgblt fb_sys_fops wwan_on_off snd_soc_gtm601 generic_adc_battery drm snd_soc_w2cbw003_bt industrialio drm_panel_orientation_quirks pwm_bl pwm_omap_dmtimer ip_tables x_tables ipv6 autofs4 [ 7.507068] CPU: 0 PID: 32 Comm: kworker/u4:2 Tainted: G W 6.1.0-rc3-letux-lpae+ #11107 [ 7.516964] Hardware name: Generic OMAP5 (Flattened Device Tree) [ 7.523284] Workqueue: events_unbound deferred_probe_work_func [ 7.529456] unwind_backtrace from show_stack+0x10/0x14 [ 7.534972] show_stack from dump_stack_lvl+0x40/0x4c [ 7.540315] dump_stack_lvl from __warn+0xb0/0x164 [ 7.545379] __warn from warn_slowpath_fmt+0x70/0x9c [ 7.550625] warn_slowpath_fmt from omap_dsi_host_detach+0x3c/0xbc [omapdrm] [ 7.558137] omap_dsi_host_detach [omapdrm] from mipi_dsi_remove_device_fn+0x10/0x20 [ 7.566376] mipi_dsi_remove_device_fn from device_for_each_child+0x60/0x94 [ 7.573729] device_for_each_child from mipi_dsi_host_unregister+0x20/0x54 [ 7.580992] mipi_dsi_host_unregister from dsi_probe+0x5d8/0x744 [omapdrm] [ 7.588315] dsi_probe [omapdrm] from platform_probe+0x58/0xa8 [ 7.594542] platform_probe from really_probe+0x144/0x2ac [ 7.600249] really_probe from __driver_probe_device+0xc4/0xd8 [ 7.606411] __driver_probe_device from driver_probe_device+0x3c/0xb8 [ 7.613216] driver_probe_device from __device_attach_driver+0x58/0xbc [ 7.620115] __device_attach_driver from bus_for_each_drv+0xa0/0xb4 [ 7.626737] bus_for_each_drv from __device_attach+0xdc/0x150 [ 7.632808] __device_attach from bus_probe_device+0x28/0x80 [ 7.638792] bus_probe_device from deferred_probe_work_func+0x84/0xa0 [ 7.645595] deferred_probe_work_func from process_one_work+0x1a4/0x2d8 [ 7.652587] process_one_work from worker_thread+0x214/0x2b8 [ 7.658567] worker_thread from kthread+0xe4/0xf0 [ 7.663542] kthread from ret_from_fork+0x14/0x1c [ 7.668515] Exception stack(0xf01b5fb0 to 0xf01b5ff8) [ 7.673827] 5fa0: 00000000 00000000 00000000 00000000 [ 7.682435] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 7.691038] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 Hope this helps to find the real cause. BR, Nikolaus
