1. Patchew
  2. linux
  3. [PATCH v6 drm-dp 0/4] Fix hibmc driver bugs
  4. View patch

[PATCH v6 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq

Yongbang Shi posted 4 patches 1 week, 3 days ago
There is a newer version of this series
[PATCH v6 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq
Posted by Yongbang Shi 1 week, 3 days ago 
From: Baihan Li <libaihan@huawei.com>

The issue is that drm_connector_helper_detect_from_ddc() returns wrong
status when plugging or unplugging the monitor. Use HPD pin status in
DP's detect_ctx() for real physcal monitor in/out, and keep using
detect_frome_ddc() if it's the first time to call detect because of
insmoding driver.

Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
Signed-off-by: Baihan Li <libaihan@huawei.com>
Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
---
ChangeLog:
v5 -> v6:
  - use HPD status in DP detect_ctx(), suggested by Dmitry Baryshkov.
v4 -> v5:
  - fix the commit message and DP detect_ctx(), suggested by Dmitry Baryshkov.
---
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c     | 12 ++++++++++++
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h     |  7 +++++++
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h    |  3 +++
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 13 +++++++++++--
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
index 8f0daec7d174..4d8d3e4d4f84 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
@@ -2,6 +2,7 @@
 // Copyright (c) 2024 Hisilicon Limited.
 
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/delay.h>
 #include "dp_config.h"
 #include "dp_comm.h"
@@ -305,3 +306,14 @@ void hibmc_dp_set_cbar(struct hibmc_dp *dp, const struct hibmc_dp_cbar_cfg *cfg)
 	hibmc_dp_reg_write_field(dp_dev, HIBMC_DP_COLOR_BAR_CTRL, BIT(0), cfg->enable);
 	writel(HIBMC_DP_SYNC_EN_MASK, dp_dev->base + HIBMC_DP_TIMING_SYNC_CTRL);
 }
+
+void hibmc_dp_update_hpd_status(struct hibmc_dp *dp)
+{
+	int status;
+
+	readl_poll_timeout(dp->dp_dev->base + HIBMC_DP_HPD_STATUS, status,
+			   FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status) != dp->hpd_status,
+			   1000, 100000); /* DP spec says 100ms */
+
+	dp->hpd_status = FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status);
+}
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
index 665f5b166dfb..8348ad9e34a8 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
@@ -14,6 +14,11 @@
 
 struct hibmc_dp_dev;
 
+enum hibmc_hpd_status {
+	HIBMC_HPD_OUT,
+	HIBMC_HPD_IN,
+};
+
 enum hibmc_dp_cbar_pattern {
 	CBAR_COLOR_BAR,
 	CBAR_WHITE,
@@ -50,6 +55,7 @@ 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);
@@ -60,5 +66,6 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp);
 void hibmc_dp_hpd_cfg(struct hibmc_dp *dp);
 void hibmc_dp_enable_int(struct hibmc_dp *dp);
 void hibmc_dp_disable_int(struct hibmc_dp *dp);
+void hibmc_dp_update_hpd_status(struct hibmc_dp *dp);
 
 #endif
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
index 394b1e933c3a..64306abcd986 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
@@ -24,6 +24,9 @@
 #define HIBMC_DP_CFG_AUX_READY_DATA_BYTE	GENMASK(16, 12)
 #define HIBMC_DP_CFG_AUX			GENMASK(24, 17)
 
+#define HIBMC_DP_HPD_STATUS			0x98
+#define HIBMC_DP_HPD_CUR_STATE		GENMASK(7, 4)
+
 #define HIBMC_DP_PHYIF_CTRL0			0xa0
 #define HIBMC_DP_CFG_SCRAMBLE_EN		BIT(0)
 #define HIBMC_DP_CFG_PAT_SEL			GENMASK(7, 4)
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index d06832e62e96..48c9c97eef0e 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -34,9 +34,16 @@ 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);
+
+	/* if no HPD just probe DDC */
+	if (!dp->irq_status)
+		return drm_connector_helper_detect_from_ddc(connector, ctx, force);
 
-	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
+	if (dp->hpd_status == HIBMC_HPD_IN)
+		return connector_status_connected;
+
+	return connector_status_disconnected;
 }
 
 static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
@@ -128,6 +135,8 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
 		hibmc_dp_reset_link(&priv->dp);
 	}
 
+	hibmc_dp_update_hpd_status(&priv->dp);
+
 	if (dev->registered)
 		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
 
-- 
2.33.0
Re: [PATCH v6 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq
Posted by Dmitry Baryshkov 1 week, 2 days ago 
On Mon, Sep 22, 2025 at 10:49:40AM +0800, Yongbang Shi wrote:
> From: Baihan Li <libaihan@huawei.com>
> 
> The issue is that drm_connector_helper_detect_from_ddc() returns wrong
> status when plugging or unplugging the monitor. Use HPD pin status in
> DP's detect_ctx() for real physcal monitor in/out, and keep using
> detect_frome_ddc() if it's the first time to call detect because of
> insmoding driver.

If I understand correct, this is not quite right. Consider DP-to-HDMI or
DP-to-DVI dongle being plugged without an actual monitor and then the
monitor being plugged later on.

> 
> Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
> Signed-off-by: Baihan Li <libaihan@huawei.com>
> Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
> ---
> ChangeLog:
> v5 -> v6:
>   - use HPD status in DP detect_ctx(), suggested by Dmitry Baryshkov.
> v4 -> v5:
>   - fix the commit message and DP detect_ctx(), suggested by Dmitry Baryshkov.
> ---
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c     | 12 ++++++++++++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h     |  7 +++++++
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h    |  3 +++
>  drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 13 +++++++++++--
>  4 files changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> index 8f0daec7d174..4d8d3e4d4f84 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> @@ -2,6 +2,7 @@
>  // Copyright (c) 2024 Hisilicon Limited.
>  
>  #include <linux/io.h>
> +#include <linux/iopoll.h>
>  #include <linux/delay.h>
>  #include "dp_config.h"
>  #include "dp_comm.h"
> @@ -305,3 +306,14 @@ void hibmc_dp_set_cbar(struct hibmc_dp *dp, const struct hibmc_dp_cbar_cfg *cfg)
>  	hibmc_dp_reg_write_field(dp_dev, HIBMC_DP_COLOR_BAR_CTRL, BIT(0), cfg->enable);
>  	writel(HIBMC_DP_SYNC_EN_MASK, dp_dev->base + HIBMC_DP_TIMING_SYNC_CTRL);
>  }
> +
> +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp)
> +{
> +	int status;
> +
> +	readl_poll_timeout(dp->dp_dev->base + HIBMC_DP_HPD_STATUS, status,
> +			   FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status) != dp->hpd_status,
> +			   1000, 100000); /* DP spec says 100ms */
> +
> +	dp->hpd_status = FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status);
> +}
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> index 665f5b166dfb..8348ad9e34a8 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> @@ -14,6 +14,11 @@
>  
>  struct hibmc_dp_dev;
>  
> +enum hibmc_hpd_status {
> +	HIBMC_HPD_OUT,
> +	HIBMC_HPD_IN,
> +};
> +
>  enum hibmc_dp_cbar_pattern {
>  	CBAR_COLOR_BAR,
>  	CBAR_WHITE,
> @@ -50,6 +55,7 @@ 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);
> @@ -60,5 +66,6 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp);
>  void hibmc_dp_hpd_cfg(struct hibmc_dp *dp);
>  void hibmc_dp_enable_int(struct hibmc_dp *dp);
>  void hibmc_dp_disable_int(struct hibmc_dp *dp);
> +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp);
>  
>  #endif
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> index 394b1e933c3a..64306abcd986 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> @@ -24,6 +24,9 @@
>  #define HIBMC_DP_CFG_AUX_READY_DATA_BYTE	GENMASK(16, 12)
>  #define HIBMC_DP_CFG_AUX			GENMASK(24, 17)
>  
> +#define HIBMC_DP_HPD_STATUS			0x98
> +#define HIBMC_DP_HPD_CUR_STATE		GENMASK(7, 4)
> +
>  #define HIBMC_DP_PHYIF_CTRL0			0xa0
>  #define HIBMC_DP_CFG_SCRAMBLE_EN		BIT(0)
>  #define HIBMC_DP_CFG_PAT_SEL			GENMASK(7, 4)
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> index d06832e62e96..48c9c97eef0e 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> @@ -34,9 +34,16 @@ 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);
> +
> +	/* if no HPD just probe DDC */
> +	if (!dp->irq_status)
> +		return drm_connector_helper_detect_from_ddc(connector, ctx, force);
>  
> -	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
> +	if (dp->hpd_status == HIBMC_HPD_IN)
> +		return connector_status_connected;
> +
> +	return connector_status_disconnected;
>  }
>  
>  static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
> @@ -128,6 +135,8 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
>  		hibmc_dp_reset_link(&priv->dp);
>  	}
>  
> +	hibmc_dp_update_hpd_status(&priv->dp);
> +
>  	if (dev->registered)
>  		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
>  
> -- 
> 2.33.0
> 

-- 
With best wishes
Dmitry
Re: [PATCH v6 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq
Posted by Yongbang Shi 1 week, 2 days ago 
> On Mon, Sep 22, 2025 at 10:49:40AM +0800, Yongbang Shi wrote:
>> From: Baihan Li <libaihan@huawei.com>
>>
>> The issue is that drm_connector_helper_detect_from_ddc() returns wrong
>> status when plugging or unplugging the monitor. Use HPD pin status in
>> DP's detect_ctx() for real physcal monitor in/out, and keep using
>> detect_frome_ddc() if it's the first time to call detect because of
>> insmoding driver.
> If I understand correct, this is not quite right. Consider DP-to-HDMI or
> DP-to-DVI dongle being plugged without an actual monitor and then the
> monitor being plugged later on.

Hi Dmitry,
Thanks for your correction. So your point is that if the HPD comes in from a dongle.
Is that okay to add those checks at the end?

         ret = drm_dp_read_dpcd_caps(dp_dev->aux, dp_dev->dpcd);
	if (ret)
		return connector_status_disconnected;

	if (!drm_dp_is_branch(dpcd))
		return connector_status_connected;

	if (drm_dp_read_sink_count_cap(connector, dp_dev->dpcd, &dp_dev->desc) &&
	    dp_dev->dpcd[DP_DOWNSTREAM_PORT_0] & DP_DS_PORT_HPD) {
		ret = drm_dp_read_sink_count(dp_dev->dpcd);
		if (ret > 0)
			return connector_status_connected;
	}

Thanks，
Baihan


>> Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
>> Signed-off-by: Baihan Li <libaihan@huawei.com>
>> Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
>> ---
>> ChangeLog:
>> v5 -> v6:
>>    - use HPD status in DP detect_ctx(), suggested by Dmitry Baryshkov.
>> v4 -> v5:
>>    - fix the commit message and DP detect_ctx(), suggested by Dmitry Baryshkov.
>> ---
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c     | 12 ++++++++++++
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h     |  7 +++++++
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h    |  3 +++
>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 13 +++++++++++--
>>   4 files changed, 33 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> index 8f0daec7d174..4d8d3e4d4f84 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> @@ -2,6 +2,7 @@
>>   // Copyright (c) 2024 Hisilicon Limited.
>>   
>>   #include <linux/io.h>
>> +#include <linux/iopoll.h>
>>   #include <linux/delay.h>
>>   #include "dp_config.h"
>>   #include "dp_comm.h"
>> @@ -305,3 +306,14 @@ void hibmc_dp_set_cbar(struct hibmc_dp *dp, const struct hibmc_dp_cbar_cfg *cfg)
>>   	hibmc_dp_reg_write_field(dp_dev, HIBMC_DP_COLOR_BAR_CTRL, BIT(0), cfg->enable);
>>   	writel(HIBMC_DP_SYNC_EN_MASK, dp_dev->base + HIBMC_DP_TIMING_SYNC_CTRL);
>>   }
>> +
>> +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp)
>> +{
>> +	int status;
>> +
>> +	readl_poll_timeout(dp->dp_dev->base + HIBMC_DP_HPD_STATUS, status,
>> +			   FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status) != dp->hpd_status,
>> +			   1000, 100000); /* DP spec says 100ms */
>> +
>> +	dp->hpd_status = FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status);
>> +}
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> index 665f5b166dfb..8348ad9e34a8 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> @@ -14,6 +14,11 @@
>>   
>>   struct hibmc_dp_dev;
>>   
>> +enum hibmc_hpd_status {
>> +	HIBMC_HPD_OUT,
>> +	HIBMC_HPD_IN,
>> +};
>> +
>>   enum hibmc_dp_cbar_pattern {
>>   	CBAR_COLOR_BAR,
>>   	CBAR_WHITE,
>> @@ -50,6 +55,7 @@ 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);
>> @@ -60,5 +66,6 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp);
>>   void hibmc_dp_hpd_cfg(struct hibmc_dp *dp);
>>   void hibmc_dp_enable_int(struct hibmc_dp *dp);
>>   void hibmc_dp_disable_int(struct hibmc_dp *dp);
>> +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp);
>>   
>>   #endif
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> index 394b1e933c3a..64306abcd986 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
>> @@ -24,6 +24,9 @@
>>   #define HIBMC_DP_CFG_AUX_READY_DATA_BYTE	GENMASK(16, 12)
>>   #define HIBMC_DP_CFG_AUX			GENMASK(24, 17)
>>   
>> +#define HIBMC_DP_HPD_STATUS			0x98
>> +#define HIBMC_DP_HPD_CUR_STATE		GENMASK(7, 4)
>> +
>>   #define HIBMC_DP_PHYIF_CTRL0			0xa0
>>   #define HIBMC_DP_CFG_SCRAMBLE_EN		BIT(0)
>>   #define HIBMC_DP_CFG_PAT_SEL			GENMASK(7, 4)
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> index d06832e62e96..48c9c97eef0e 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> @@ -34,9 +34,16 @@ 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);
>> +
>> +	/* if no HPD just probe DDC */
>> +	if (!dp->irq_status)
>> +		return drm_connector_helper_detect_from_ddc(connector, ctx, force);
>>   
>> -	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
>> +	if (dp->hpd_status == HIBMC_HPD_IN)
>> +		return connector_status_connected;
>> +
>> +	return connector_status_disconnected;
>>   }
>>   
>>   static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
>> @@ -128,6 +135,8 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
>>   		hibmc_dp_reset_link(&priv->dp);
>>   	}
>>   
>> +	hibmc_dp_update_hpd_status(&priv->dp);
>> +
>>   	if (dev->registered)
>>   		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
>>   
>> -- 
>> 2.33.0
>>
Re: [PATCH v6 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq
Posted by Dmitry Baryshkov 1 week, 2 days ago 
On Tue, Sep 23, 2025 at 10:57:56AM +0800, Yongbang Shi wrote:
> > On Mon, Sep 22, 2025 at 10:49:40AM +0800, Yongbang Shi wrote:
> > > From: Baihan Li <libaihan@huawei.com>
> > > 
> > > The issue is that drm_connector_helper_detect_from_ddc() returns wrong
> > > status when plugging or unplugging the monitor. Use HPD pin status in
> > > DP's detect_ctx() for real physcal monitor in/out, and keep using
> > > detect_frome_ddc() if it's the first time to call detect because of
> > > insmoding driver.
> > If I understand correct, this is not quite right. Consider DP-to-HDMI or
> > DP-to-DVI dongle being plugged without an actual monitor and then the
> > monitor being plugged later on.
> 
> Hi Dmitry,
> Thanks for your correction. So your point is that if the HPD comes in from a dongle.
> Is that okay to add those checks at the end?
> 
>         ret = drm_dp_read_dpcd_caps(dp_dev->aux, dp_dev->dpcd);
> 	if (ret)
> 		return connector_status_disconnected;
> 
> 	if (!drm_dp_is_branch(dpcd))
> 		return connector_status_connected;
> 
> 	if (drm_dp_read_sink_count_cap(connector, dp_dev->dpcd, &dp_dev->desc) &&
> 	    dp_dev->dpcd[DP_DOWNSTREAM_PORT_0] & DP_DS_PORT_HPD) {
> 		ret = drm_dp_read_sink_count(dp_dev->dpcd);
> 		if (ret > 0)
> 			return connector_status_connected;
> 	}

Yes

> 
> Thanks，
> Baihan
> 
> 
> > > Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
> > > Signed-off-by: Baihan Li <libaihan@huawei.com>
> > > Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
> > > ---
> > > ChangeLog:
> > > v5 -> v6:
> > >    - use HPD status in DP detect_ctx(), suggested by Dmitry Baryshkov.
> > > v4 -> v5:
> > >    - fix the commit message and DP detect_ctx(), suggested by Dmitry Baryshkov.
> > > ---
> > >   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c     | 12 ++++++++++++
> > >   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h     |  7 +++++++
> > >   drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h    |  3 +++
> > >   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 13 +++++++++++--
> > >   4 files changed, 33 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> > > index 8f0daec7d174..4d8d3e4d4f84 100644
> > > --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> > > +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> > > @@ -2,6 +2,7 @@
> > >   // Copyright (c) 2024 Hisilicon Limited.
> > >   #include <linux/io.h>
> > > +#include <linux/iopoll.h>
> > >   #include <linux/delay.h>
> > >   #include "dp_config.h"
> > >   #include "dp_comm.h"
> > > @@ -305,3 +306,14 @@ void hibmc_dp_set_cbar(struct hibmc_dp *dp, const struct hibmc_dp_cbar_cfg *cfg)
> > >   	hibmc_dp_reg_write_field(dp_dev, HIBMC_DP_COLOR_BAR_CTRL, BIT(0), cfg->enable);
> > >   	writel(HIBMC_DP_SYNC_EN_MASK, dp_dev->base + HIBMC_DP_TIMING_SYNC_CTRL);
> > >   }
> > > +
> > > +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp)
> > > +{
> > > +	int status;
> > > +
> > > +	readl_poll_timeout(dp->dp_dev->base + HIBMC_DP_HPD_STATUS, status,
> > > +			   FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status) != dp->hpd_status,
> > > +			   1000, 100000); /* DP spec says 100ms */
> > > +
> > > +	dp->hpd_status = FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status);
> > > +}
> > > diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > > index 665f5b166dfb..8348ad9e34a8 100644
> > > --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > > +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
> > > @@ -14,6 +14,11 @@
> > >   struct hibmc_dp_dev;
> > > +enum hibmc_hpd_status {
> > > +	HIBMC_HPD_OUT,
> > > +	HIBMC_HPD_IN,
> > > +};
> > > +
> > >   enum hibmc_dp_cbar_pattern {
> > >   	CBAR_COLOR_BAR,
> > >   	CBAR_WHITE,
> > > @@ -50,6 +55,7 @@ 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);
> > > @@ -60,5 +66,6 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp);
> > >   void hibmc_dp_hpd_cfg(struct hibmc_dp *dp);
> > >   void hibmc_dp_enable_int(struct hibmc_dp *dp);
> > >   void hibmc_dp_disable_int(struct hibmc_dp *dp);
> > > +void hibmc_dp_update_hpd_status(struct hibmc_dp *dp);
> > >   #endif
> > > diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> > > index 394b1e933c3a..64306abcd986 100644
> > > --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> > > +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h
> > > @@ -24,6 +24,9 @@
> > >   #define HIBMC_DP_CFG_AUX_READY_DATA_BYTE	GENMASK(16, 12)
> > >   #define HIBMC_DP_CFG_AUX			GENMASK(24, 17)
> > > +#define HIBMC_DP_HPD_STATUS			0x98
> > > +#define HIBMC_DP_HPD_CUR_STATE		GENMASK(7, 4)
> > > +
> > >   #define HIBMC_DP_PHYIF_CTRL0			0xa0
> > >   #define HIBMC_DP_CFG_SCRAMBLE_EN		BIT(0)
> > >   #define HIBMC_DP_CFG_PAT_SEL			GENMASK(7, 4)
> > > diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > > index d06832e62e96..48c9c97eef0e 100644
> > > --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > > +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
> > > @@ -34,9 +34,16 @@ 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);
> > > +
> > > +	/* if no HPD just probe DDC */
> > > +	if (!dp->irq_status)
> > > +		return drm_connector_helper_detect_from_ddc(connector, ctx, force);
> > > -	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
> > > +	if (dp->hpd_status == HIBMC_HPD_IN)
> > > +		return connector_status_connected;
> > > +
> > > +	return connector_status_disconnected;
> > >   }
> > >   static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
> > > @@ -128,6 +135,8 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
> > >   		hibmc_dp_reset_link(&priv->dp);
> > >   	}
> > > +	hibmc_dp_update_hpd_status(&priv->dp);
> > > +
> > >   	if (dev->registered)
> > >   		drm_connector_helper_hpd_irq_event(&priv->dp.connector);
> > > -- 
> > > 2.33.0
> > > 

-- 
With best wishes
Dmitry

Patchew 2.1-devel-b67e4c2

© 2016 - 2025 Red Hat, Inc.