On Fri, 13 Jan 2023 at 09:12, Laurentiu Palcu
<laurentiu.palcu@xxxxxxxxxxx> wrote:
>
> 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.
Argh. Too many refactorings. I'll check that it works correctly and respin.
>
> 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
> >
--
With best wishes
Dmitry
