Re: [PATCH drm-dp 02/10] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq

[Yongbang Shi]

> On Fri, May 30, 2025 at 05:54:24PM +0800, Yongbang Shi wrote:
> > From: Baihan Li <libaihan@xxxxxxxxxx>
> >
> > The debouncing when HPD pulled out still remains sometimes, 200ms still can
> > not ensure helper_detect() is correct. So add a flag to hold the sink
> > status, and changed detect_ctx() functions by using flag to check status.
> >
> > Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
> > Signed-off-by: Baihan Li <libaihan@xxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h    |  1 +
> >   .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 38 +++++++++++++------
> >   2 files changed, 28 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > index 665f5b166dfb..68867475508c 100644
> > --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > @@ -50,6 +50,7 @@ struct hibmc_dp {
> >   	struct drm_dp_aux aux;
> >   	struct hibmc_dp_cbar_cfg cfg;
> >   	u32 irq_status;
> > +	int hpd_status;
> >   };
> >   
> >   int hibmc_dp_hw_init(struct hibmc_dp *dp);
> > diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > index d06832e62e96..191fb434baa7 100644
> > --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > @@ -13,7 +13,8 @@
> >   #include "hibmc_drm_drv.h"
> >   #include "dp/dp_hw.h"
> >   
> > -#define DP_MASKED_SINK_HPD_PLUG_INT	BIT(2)
> > +#define HIBMC_DP_MASKED_SINK_HPD_PLUG_INT	BIT(2)
> > +#define HIBMC_DP_MASKED_SINK_HPD_UNPLUG_INT	BIT(3)
> >   
> >   static int hibmc_dp_connector_get_modes(struct drm_connector *connector)
> >   {
> > @@ -34,9 +35,12 @@ static int hibmc_dp_connector_get_modes(struct drm_connector *connector)
> >   static int hibmc_dp_detect(struct drm_connector *connector,
> >   			   struct drm_modeset_acquire_ctx *ctx, bool force)
> >   {
> > -	mdelay(200);
> > +	struct hibmc_dp *dp = to_hibmc_dp(connector);
> >   
> > -	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
> > +	if (dp->hpd_status)
> > +		return connector_status_connected;
> > +	else
> > +		return connector_status_disconnected;
> >   }
> >   
> >   static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
> > @@ -115,22 +119,34 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
> >   {
> >   	struct drm_device *dev = (struct drm_device *)arg;
> >   	struct hibmc_drm_private *priv = to_hibmc_drm_private(dev);
> > +	struct hibmc_dp *dp = &priv->dp;
> >   	int idx;
> >   
> >   	if (!drm_dev_enter(dev, &idx))
> >   		return -ENODEV;
> >   
> > -	if (priv->dp.irq_status & DP_MASKED_SINK_HPD_PLUG_INT) {
> > -		drm_dbg_dp(&priv->dev, "HPD IN isr occur!\n");
> > -		hibmc_dp_hpd_cfg(&priv->dp);
> > +	if (dp->hpd_status) { /* only check unplug int when the last status is HPD in */
> I think this way you'll ignore HPD short pulses. Could you possibly
> clarify whether it is the case or not?

We actually doesn't enable short HPD here, this feature just used in our electrical tests.


> > +		if ((dp->irq_status & HIBMC_DP_MASKED_SINK_HPD_UNPLUG_INT)) {
> > +			drm_dbg_dp(dev, "HPD OUT isr occur.");
> > +			hibmc_dp_reset_link(dp);
> > +			dp->hpd_status = 0;
> > +			if (dev->registered)
> > +				drm_connector_helper_hpd_irq_event(&dp->connector);
> > +		} else {
> > +			drm_warn(dev, "HPD OUT occurs, irq status err: %u", dp->irq_status);
> These should be ratelimited.

Sorry, I didn't get it. Do you mean I need print the link rate here?


> > +		}
> >   	} else {
> > -		drm_dbg_dp(&priv->dev, "HPD OUT isr occur!\n");
> > -		hibmc_dp_reset_link(&priv->dp);
> > +		if (dp->irq_status & HIBMC_DP_MASKED_SINK_HPD_PLUG_INT) {
> > +			drm_dbg_dp(&priv->dev, "HPD IN isr occur.");
> > +			hibmc_dp_hpd_cfg(dp);
> > +			dp->hpd_status = 1;
> > +			if (dev->registered)
> > +				drm_connector_helper_hpd_irq_event(&dp->connector);
> > +		} else {
> > +			drm_warn(dev, "HPD IN occurs, irq status err: %u", dp->irq_status);
> > +		}
> >   	}
> >   
> > -	if (dev->registered)
> > -		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
> There is no need to, just call this function always at the end of the
> ISR handler as it is done currently.

Ok.


> > -
> >   	drm_dev_exit(idx);
> >   
> >   	return IRQ_HANDLED;
> > --
> > 2.33.0