On 20/01/2023 18:39, Laurent Pinchart wrote:
Hi Dmitry, Thank you for the patch. On Wed, Jan 18, 2023 at 01:39:05AM +0200, Dmitry Baryshkov wrote:There are two flags attemting to guard connector polling: poll_enabled and poll_running. While poll_enabled semantics is clearly defined and fully adhered (mark that drm_kms_helper_poll_init() was called and not finalized by the _fini() call), the poll_running flag doesn't have such clearliness. This flag is used only in drm_helper_probe_single_connector_modes() to guard calling of drm_kms_helper_poll_enable, it doesn't guard the drm_kms_helper_poll_fini(), etc. Change it to only be set if the polling is actually running. Tie HPD enablement to this flag. This fixes the following warning reported after merging the HPD series: Hot plug detection already enabled WARNING: CPU: 2 PID: 9 at drivers/gpu/drm/drm_bridge.c:1257 drm_bridge_hpd_enable+0x94/0x9c [drm] Modules linked in: videobuf2_memops snd_soc_simple_card snd_soc_simple_card_utils fsl_imx8_ddr_perf videobuf2_common snd_soc_imx_spdif adv7511 etnaviv imx8m_ddrc imx_dcss mc cec nwl_dsi gov CPU: 2 PID: 9 Comm: kworker/u8:0 Not tainted 6.2.0-rc2-15208-g25b283acd578 #6 Hardware name: NXP i.MX8MQ EVK (DT) Workqueue: events_unbound deferred_probe_work_func pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : drm_bridge_hpd_enable+0x94/0x9c [drm] lr : drm_bridge_hpd_enable+0x94/0x9c [drm] sp : ffff800009ef3740 x29: ffff800009ef3740 x28: ffff000009331f00 x27: 0000000000001000 x26: 0000000000000020 x25: ffff800001148ed8 x24: ffff00000a8fe000 x23: 00000000fffffffd x22: ffff000005086348 x21: ffff800001133ee0 x20: ffff00000550d800 x19: ffff000005086288 x18: 0000000000000006 x17: 0000000000000000 x16: ffff8000096ef008 x15: 97ffff2891004260 x14: 2a1403e194000000 x13: 97ffff2891004260 x12: 2a1403e194000000 x11: 7100385f29400801 x10: 0000000000000aa0 x9 : ffff800008112744 x8 : ffff000000250b00 x7 : 0000000000000003 x6 : 0000000000000011 x5 : 0000000000000000 x4 : ffff0000bd986a48 x3 : 0000000000000001 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000000250000 Call trace: drm_bridge_hpd_enable+0x94/0x9c [drm] drm_bridge_connector_enable_hpd+0x2c/0x3c [drm_kms_helper] drm_kms_helper_poll_enable+0x94/0x10c [drm_kms_helper] drm_helper_probe_single_connector_modes+0x1a8/0x510 [drm_kms_helper] drm_client_modeset_probe+0x204/0x1190 [drm] __drm_fb_helper_initial_config_and_unlock+0x5c/0x4a4 [drm_kms_helper] drm_fb_helper_initial_config+0x54/0x6c [drm_kms_helper] drm_fbdev_client_hotplug+0xd0/0x140 [drm_kms_helper] drm_fbdev_generic_setup+0x90/0x154 [drm_kms_helper] dcss_kms_attach+0x1c8/0x254 [imx_dcss] dcss_drv_platform_probe+0x90/0xfc [imx_dcss] platform_probe+0x70/0xcc really_probe+0xc4/0x2e0 __driver_probe_device+0x80/0xf0 driver_probe_device+0xe0/0x164 __device_attach_driver+0xc0/0x13c bus_for_each_drv+0x84/0xe0 __device_attach+0xa4/0x1a0 device_initial_probe+0x1c/0x30 bus_probe_device+0xa4/0xb0 deferred_probe_work_func+0x90/0xd0 process_one_work+0x200/0x474 worker_thread+0x74/0x43c kthread+0xfc/0x110 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- Reported-by: Laurentiu Palcu <laurentiu.palcu@xxxxxxxxxxx> Fixes: c8268795c9a9 ("drm/probe-helper: enable and disable HPD on connectors") Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Tested-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>This fixes the issue on my Renesas boards. Tested-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> Please see below for a few comments.
[skipped two small comments, will fix them in v3]
@@ -886,7 +897,12 @@ EXPORT_SYMBOL(drm_kms_helper_poll_init); */ void drm_kms_helper_poll_fini(struct drm_device *dev) { - drm_kms_helper_poll_disable_fini(dev, true); + if (!dev->mode_config.poll_enabled) + return; + + drm_kms_helper_poll_disable(dev); + + dev->mode_config.poll_enabled = false;The fact that poll_enabled guard init/fini and poll_running guards enable/disable is confusing :-S It would be nice if the poll_enable flag matched the enable/disable function names. One option could be - drm_kms_helper_poll_enable() -> drm_kms_helper_poll_resume() - drm_kms_helper_poll_disable() -> drm_kms_helper_poll_suspend() - drm_kms_helper_poll_init() -> drm_kms_helper_poll_enable() - drm_kms_helper_poll_fini() -> drm_kms_helper_poll_disable() This would align quite well with intended usage in drivers I think, the current enable/disable functions are documented as being used by drivers for suspend/resume, and the init()/fini() functions are documented as "init and enable" and "disable and cleanup". This isn't a candidate for this patch of course, it can be done on top.
Yes, but I'd extremely dislike renaming a function to use the name of the function that existed previously. It can lead to very confusing issue.
What do you think about keeping poll_init()/_fini() as is, reaming dev->mode_config.poll_enabled to poll_initialized, and renaming poll_enable()/disable() to suspend()/resume() as you suggested?
} EXPORT_SYMBOL(drm_kms_helper_poll_fini);
-- With best wishes Dmitry
