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Message-ID: <20251017095907.2060834-2-shiyongbang@huawei.com>
Date: Fri, 17 Oct 2025 17:59:04 +0800
From: Yongbang Shi <shiyongbang@...wei.com>
To: <xinliang.liu@...aro.org>, <tiantao6@...ilicon.com>,
<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
<kong.kongxinwei@...ilicon.com>, <dmitry.baryshkov@....qualcomm.com>
CC: <liangjian010@...wei.com>, <chenjianmin@...wei.com>,
<fengsheng5@...wei.com>, <shiyongbang@...wei.com>, <libaihan@...wei.com>,
<shenjian15@...wei.com>, <shaojijie@...wei.com>,
<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v9 drm-dp 1/4] drm/hisilicon/hibmc: fix dp probabilistical detect errors after HPD irq
From: Baihan Li <libaihan@...wei.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 implementation
a complete DP detection including read DPCD, check if it's a branch
device and its sink count for different situations.
Do a double check that adding HPD check and get DPCD at the beginning of
DP encoder enable stage.
Fixes: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
Signed-off-by: Baihan Li <libaihan@...wei.com>
Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
---
ChangeLog:
v8 -> v9:
- refactor the hibmc_dp_check_hpd_status(), and add some checks
in dp_encoder_enable.
v7 -> v8:
- fix build errors reported by kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509241625.o4mNleVb-lkp@intel.com/
v6 -> v7:
- add the check about branch devices, suggested by Dmitry Baryshkov.
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_comm.h | 4 ++
drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c | 21 +++++++
drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h | 6 ++
drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h | 3 +
.../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c | 58 +++++++++++++++++--
5 files changed, 88 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
index 4add05c7f161..f9ee7ebfec55 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_comm.h
@@ -40,6 +40,10 @@ struct hibmc_dp_dev {
struct mutex lock; /* protects concurrent RW in hibmc_dp_reg_write_field() */
struct hibmc_dp_link link;
u8 dpcd[DP_RECEIVER_CAP_SIZE];
+ u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
+ struct drm_dp_desc desc;
+ bool is_branch;
+ int hpd_status;
void __iomem *serdes_base;
};
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
index 8f0daec7d174..8e91ded0dd37 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 +306,23 @@ 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);
}
+
+bool hibmc_dp_check_hpd_status(struct hibmc_dp *dp, int exp_status)
+{
+ u32 status;
+ int ret;
+
+ msleep(100);
+
+ ret = readl_poll_timeout(dp->dp_dev->base + HIBMC_DP_HPD_STATUS, status,
+ FIELD_GET(HIBMC_DP_HPD_CUR_STATE, status) == exp_status,
+ 1000, 100000); /* DP spec says 100ms */
+ if (ret) {
+ drm_dbg_dp(dp->drm_dev, "wait hpd status timeout");
+ return false;
+ }
+
+ dp->dp_dev->hpd_status = exp_status;
+
+ return true;
+}
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
index 665f5b166dfb..59c1eae153c5 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,
@@ -60,5 +65,6 @@ 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);
+bool hibmc_dp_check_hpd_status(struct hibmc_dp *dp, int exp_status);
#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..5cdbd0882de8 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -12,6 +12,7 @@
#include "hibmc_drm_drv.h"
#include "dp/dp_hw.h"
+#include "dp/dp_comm.h"
#define DP_MASKED_SINK_HPD_PLUG_INT BIT(2)
@@ -31,12 +32,53 @@ static int hibmc_dp_connector_get_modes(struct drm_connector *connector)
return count;
}
+static bool hibmc_dp_get_dpcd(struct hibmc_dp_dev *dp_dev)
+{
+ int ret;
+
+ ret = drm_dp_read_dpcd_caps(dp_dev->aux, dp_dev->dpcd);
+ if (ret)
+ return false;
+
+ dp_dev->is_branch = drm_dp_is_branch(dp_dev->dpcd);
+
+ ret = drm_dp_read_desc(dp_dev->aux, &dp_dev->desc, dp_dev->is_branch);
+ if (ret)
+ return false;
+
+ ret = drm_dp_read_downstream_info(dp_dev->aux, dp_dev->dpcd, dp_dev->downstream_ports);
+ if (ret)
+ return false;
+
+ return true;
+}
+
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);
+ struct hibmc_dp_dev *dp_dev = dp->dp_dev;
+ int ret;
+
+ if (dp->irq_status) {
+ if (dp_dev->hpd_status != HIBMC_HPD_IN)
+ return connector_status_disconnected;
+ }
+
+ if (!hibmc_dp_get_dpcd(dp_dev))
+ return connector_status_disconnected;
+
+ if (!dp_dev->is_branch)
+ return connector_status_connected;
- return drm_connector_helper_detect_from_ddc(connector, ctx, force);
+ if (drm_dp_read_sink_count_cap(connector, dp_dev->dpcd, &dp_dev->desc) &&
+ dp_dev->downstream_ports[0] & DP_DS_PORT_HPD) {
+ ret = drm_dp_read_sink_count(dp_dev->aux);
+ if (ret > 0)
+ return connector_status_connected;
+ }
+
+ return connector_status_disconnected;
}
static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
@@ -92,6 +134,12 @@ static void hibmc_dp_encoder_enable(struct drm_encoder *drm_encoder,
struct hibmc_dp *dp = container_of(drm_encoder, struct hibmc_dp, encoder);
struct drm_display_mode *mode = &drm_encoder->crtc->state->mode;
+ if (!hibmc_dp_check_hpd_status(dp, HIBMC_HPD_IN))
+ return;
+
+ if (!hibmc_dp_get_dpcd(dp->dp_dev))
+ return;
+
if (hibmc_dp_prepare(dp, mode))
return;
@@ -115,7 +163,7 @@ 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);
- int idx;
+ int idx, exp_status;
if (!drm_dev_enter(dev, &idx))
return -ENODEV;
@@ -123,12 +171,14 @@ irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg)
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);
+ exp_status = HIBMC_HPD_IN;
} else {
drm_dbg_dp(&priv->dev, "HPD OUT isr occur!\n");
hibmc_dp_reset_link(&priv->dp);
+ exp_status = HIBMC_HPD_OUT;
}
- if (dev->registered)
+ if (hibmc_dp_check_hpd_status(&priv->dp, exp_status))
drm_connector_helper_hpd_irq_event(&priv->dp.connector);
drm_dev_exit(idx);
--
2.33.0
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