Hi Dmitry,
On Thu, Jan 12, 2023 at 05:42:47PM +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 fix the following warning reported after merging the HPD series:
s/fix/fixes/
>
> 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")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_probe_helper.c | 110 +++++++++++++++++------------
> 1 file changed, 63 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 7973f2589ced..ef919d95fea6 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -222,6 +222,45 @@ drm_connector_mode_valid(struct drm_connector *connector,
> return ret;
> }
>
> +static void drm_kms_helper_disable_hpd(struct drm_device *dev)
> +{
> + struct drm_connector *connector;
> + struct drm_connector_list_iter conn_iter;
> +
> + drm_connector_list_iter_begin(dev, &conn_iter);
> + drm_for_each_connector_iter(connector, &conn_iter) {
> + const struct drm_connector_helper_funcs *funcs =
> + connector->helper_private;
> +
> + if (funcs && funcs->disable_hpd)
> + funcs->disable_hpd(connector);
> + }
> + drm_connector_list_iter_end(&conn_iter);
> +}
> +
> +static bool drm_kms_helper_enable_hpd(struct drm_device *dev)
> +{
> + bool poll = false;
> + struct drm_connector *connector;
> + struct drm_connector_list_iter conn_iter;
> +
> + drm_connector_list_iter_begin(dev, &conn_iter);
> + drm_for_each_connector_iter(connector, &conn_iter) {
> + const struct drm_connector_helper_funcs *funcs =
> + connector->helper_private;
> +
> + if (funcs && funcs->disable_hpd)
> + funcs->disable_hpd(connector);
I believe this is not right. You probably wanted to use enable_hpd
instead of disable_hpd on these two lines? Otherwise HPD would not work
at all.
Thanks,
Laurentiu
> +
> + if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
> + DRM_CONNECTOR_POLL_DISCONNECT))
> + poll = true;
> + }
> + drm_connector_list_iter_end(&conn_iter);
> +
> + return poll;
> +}
> +
> #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
> /**
> * drm_kms_helper_poll_enable - re-enable output polling.
> @@ -241,26 +280,14 @@ drm_connector_mode_valid(struct drm_connector *connector,
> void drm_kms_helper_poll_enable(struct drm_device *dev)
> {
> bool poll = false;
> - struct drm_connector *connector;
> - struct drm_connector_list_iter conn_iter;
> unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
>
> - if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
> + if (!dev->mode_config.poll_enabled ||
> + !drm_kms_helper_poll ||
> + dev->mode_config.poll_running)
> return;
>
> - drm_connector_list_iter_begin(dev, &conn_iter);
> - drm_for_each_connector_iter(connector, &conn_iter) {
> - const struct drm_connector_helper_funcs *funcs =
> - connector->helper_private;
> -
> - if (funcs && funcs->enable_hpd)
> - funcs->enable_hpd(connector);
> -
> - if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
> - DRM_CONNECTOR_POLL_DISCONNECT))
> - poll = true;
> - }
> - drm_connector_list_iter_end(&conn_iter);
> + poll = drm_kms_helper_enable_hpd(dev);
>
> if (dev->mode_config.delayed_event) {
> /*
> @@ -279,6 +306,8 @@ void drm_kms_helper_poll_enable(struct drm_device *dev)
>
> if (poll)
> schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
> +
> + dev->mode_config.poll_running = true;
> }
> EXPORT_SYMBOL(drm_kms_helper_poll_enable);
>
> @@ -567,10 +596,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
> }
>
> /* Re-enable polling in case the global poll config changed. */
> - if (drm_kms_helper_poll != dev->mode_config.poll_running)
> - drm_kms_helper_poll_enable(dev);
> -
> - dev->mode_config.poll_running = drm_kms_helper_poll;
> + drm_kms_helper_poll_enable(dev);
>
> if (connector->status == connector_status_disconnected) {
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
> @@ -710,8 +736,12 @@ static void output_poll_execute(struct work_struct *work)
> changed = dev->mode_config.delayed_event;
> dev->mode_config.delayed_event = false;
>
> - if (!drm_kms_helper_poll)
> + if (!drm_kms_helper_poll &&
> + dev->mode_config.poll_running) {
> + drm_kms_helper_disable_hpd(dev);
> + dev->mode_config.poll_running = false;
> goto out;
> + }
>
> if (!mutex_trylock(&dev->mode_config.mutex)) {
> repoll = true;
> @@ -808,30 +838,6 @@ bool drm_kms_helper_is_poll_worker(void)
> }
> EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
>
> -static void drm_kms_helper_poll_disable_fini(struct drm_device *dev, bool fini)
> -{
> - struct drm_connector *connector;
> - struct drm_connector_list_iter conn_iter;
> -
> - if (!dev->mode_config.poll_enabled)
> - return;
> -
> - if (fini)
> - dev->mode_config.poll_enabled = false;
> -
> - drm_connector_list_iter_begin(dev, &conn_iter);
> - drm_for_each_connector_iter(connector, &conn_iter) {
> - const struct drm_connector_helper_funcs *funcs =
> - connector->helper_private;
> -
> - if (funcs && funcs->disable_hpd)
> - funcs->disable_hpd(connector);
> - }
> - drm_connector_list_iter_end(&conn_iter);
> -
> - cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
> -}
> -
> /**
> * drm_kms_helper_poll_disable - disable output polling
> * @dev: drm_device
> @@ -848,7 +854,12 @@ static void drm_kms_helper_poll_disable_fini(struct drm_device *dev, bool fini)
> */
> void drm_kms_helper_poll_disable(struct drm_device *dev)
> {
> - drm_kms_helper_poll_disable_fini(dev, false);
> + if (dev->mode_config.poll_running)
> + drm_kms_helper_disable_hpd(dev);
> +
> + cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
> +
> + dev->mode_config.poll_running = false;
> }
> EXPORT_SYMBOL(drm_kms_helper_poll_disable);
>
> @@ -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;
> }
> EXPORT_SYMBOL(drm_kms_helper_poll_fini);
>
> --
> 2.39.0
>
