linux-kernel - [PATCH v5 drm-dp 2/4] drm/hisilicon/hibmc: add dp mode valid check

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Message-ID: <20250826021744.3237574-3-shiyongbang@huawei.com>
Date: Tue, 26 Aug 2025 10:17:42 +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 v5 drm-dp 2/4] drm/hisilicon/hibmc: add dp mode valid check

From: Baihan Li <libaihan@...wei.com>

If DP is connected, check the DP BW in mode_valid_ctx() to ensure
that DP's link rate supports high-resolution data transmission.

Fixes: 0ab6ea261c1f ("drm/hisilicon/hibmc: add dp module in hibmc")
Signed-off-by: Baihan Li <libaihan@...wei.com>
Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
ChangeLog:
v4 -> v5:
  - fix bugfix commit ID, suggested by Dmitry Baryshkov.
---
 .../gpu/drm/hisilicon/hibmc/dp/dp_config.h    |  2 ++
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    | 10 ++++++++++
 drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h    |  2 ++
 .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 19 +++++++++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
index 08f9e1caf7fc..efb30a758475 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_config.h
@@ -17,5 +17,7 @@
 #define HIBMC_DP_LINK_RATE_CAL		27
 #define HIBMC_DP_SYNC_DELAY(lanes)	((lanes) == 0x2 ? 86 : 46)
 #define HIBMC_DP_INT_ENABLE		0xc
+/* HIBMC_DP_LINK_RATE_CAL * 10000 * 80% = 216000 */
+#define DP_MODE_VALI_CAL		216000
 
 #endif
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
index 8f0daec7d174..f8e1b437c385 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
@@ -263,6 +263,16 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp)
 	dp->dp_dev->link.status.channel_equalized = false;
 }
 
+u8 hibmc_dp_get_link_rate(struct hibmc_dp *dp)
+{
+	return dp->dp_dev->link.cap.link_rate;
+}
+
+u8 hibmc_dp_get_lanes(struct hibmc_dp *dp)
+{
+	return dp->dp_dev->link.cap.lanes;
+}
+
 static const struct hibmc_dp_color_raw g_rgb_raw[] = {
 	{CBAR_COLOR_BAR, 0x000, 0x000, 0x000},
 	{CBAR_WHITE,     0xfff, 0xfff, 0xfff},
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
index 665f5b166dfb..312cf7920037 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
@@ -60,5 +60,7 @@ 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);
+u8 hibmc_dp_get_link_rate(struct hibmc_dp *dp);
+u8 hibmc_dp_get_lanes(struct hibmc_dp *dp);
 
 #endif
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index 123372ae2d40..d0d0900121df 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -13,6 +13,7 @@
 #include "hibmc_drm_drv.h"
 #include "dp/dp_hw.h"
 #include "dp/dp_comm.h"
+#include "dp/dp_config.h"
 
 #define DP_MASKED_SINK_HPD_PLUG_INT	BIT(2)
 
@@ -49,9 +50,27 @@ static int hibmc_dp_detect(struct drm_connector *connector,
 	return drm_connector_helper_detect_from_ddc(connector, ctx, force);
 }
 
+static int hibmc_dp_mode_valid(struct drm_connector *connector,
+			       const struct drm_display_mode *mode,
+			       struct drm_modeset_acquire_ctx *ctx,
+			       enum drm_mode_status *status)
+{
+	struct hibmc_dp *dp = to_hibmc_dp(connector);
+	u64 cur_val, max_val;
+
+	/* check DP link BW */
+	cur_val = (u64)mode->clock * HIBMC_DP_BPP;
+	max_val = (u64)hibmc_dp_get_link_rate(dp) * DP_MODE_VALI_CAL * hibmc_dp_get_lanes(dp);
+
+	*status = cur_val > max_val ? MODE_CLOCK_HIGH : MODE_OK;
+
+	return 0;
+}
+
 static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
 	.get_modes = hibmc_dp_connector_get_modes,
 	.detect_ctx = hibmc_dp_detect,
+	.mode_valid_ctx = hibmc_dp_mode_valid,
 };
 
 static int hibmc_dp_late_register(struct drm_connector *connector)
-- 
2.33.0