1 files changed, 398 insertions, 23 deletions

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index b1ca3a1100da..61c7c2c588c6 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -22,19 +22,21 @@
 
 #include <linux/backlight.h>
 #include <linux/delay.h>
+#include <linux/dynamic_debug.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/string_helpers.h>
-#include <linux/dynamic_debug.h>
 
 #include <drm/display/drm_dp_helper.h>
 #include <drm/display/drm_dp_mst_helper.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_fixed.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 #include <drm/drm_panel.h>
@@ -533,6 +535,15 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	mutex_lock(&aux->hw_mutex);
 
 	/*
+	 * If the device attached to the aux bus is powered down then there's
+	 * no reason to attempt a transfer. Error out immediately.
+	 */
+	if (aux->powered_down) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	/*
 	 * The specification doesn't give any recommendation on how often to
 	 * retry native transactions. We used to retry 7 times like for
 	 * aux i2c transactions but real world devices this wasn't
@@ -600,6 +611,29 @@ int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset)
 EXPORT_SYMBOL(drm_dp_dpcd_probe);
 
 /**
+ * drm_dp_dpcd_set_powered() - Set whether the DP device is powered
+ * @aux: DisplayPort AUX channel; for convenience it's OK to pass NULL here
+ *       and the function will be a no-op.
+ * @powered: true if powered; false if not
+ *
+ * If the endpoint device on the DP AUX bus is known to be powered down
+ * then this function can be called to make future transfers fail immediately
+ * instead of needing to time out.
+ *
+ * If this function is never called then a device defaults to being powered.
+ */
+void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered)
+{
+	if (!aux)
+		return;
+
+	mutex_lock(&aux->hw_mutex);
+	aux->powered_down = !powered;
+	mutex_unlock(&aux->hw_mutex);
+}
+EXPORT_SYMBOL(drm_dp_dpcd_set_powered);
+
+/**
  * drm_dp_dpcd_read() - read a series of bytes from the DPCD
  * @aux: DisplayPort AUX channel (SST or MST)
  * @offset: address of the (first) register to read
@@ -746,6 +780,128 @@ int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_dpcd_read_phy_link_status);
 
+static int read_payload_update_status(struct drm_dp_aux *aux)
+{
+	int ret;
+	u8 status;
+
+	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
+	if (ret < 0)
+		return ret;
+
+	return status;
+}
+
+/**
+ * drm_dp_dpcd_write_payload() - Write Virtual Channel information to payload table
+ * @aux: DisplayPort AUX channel
+ * @vcpid: Virtual Channel Payload ID
+ * @start_time_slot: Starting time slot
+ * @time_slot_count: Time slot count
+ *
+ * Write the Virtual Channel payload allocation table, checking the payload
+ * update status and retrying as necessary.
+ *
+ * Returns:
+ * 0 on success, negative error otherwise
+ */
+int drm_dp_dpcd_write_payload(struct drm_dp_aux *aux,
+			      int vcpid, u8 start_time_slot, u8 time_slot_count)
+{
+	u8 payload_alloc[3], status;
+	int ret;
+	int retries = 0;
+
+	drm_dp_dpcd_writeb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
+			   DP_PAYLOAD_TABLE_UPDATED);
+
+	payload_alloc[0] = vcpid;
+	payload_alloc[1] = start_time_slot;
+	payload_alloc[2] = time_slot_count;
+
+	ret = drm_dp_dpcd_write(aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
+	if (ret != 3) {
+		drm_dbg_kms(aux->drm_dev, "failed to write payload allocation %d\n", ret);
+		goto fail;
+	}
+
+retry:
+	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
+	if (ret < 0) {
+		drm_dbg_kms(aux->drm_dev, "failed to read payload table status %d\n", ret);
+		goto fail;
+	}
+
+	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
+		retries++;
+		if (retries < 20) {
+			usleep_range(10000, 20000);
+			goto retry;
+		}
+		drm_dbg_kms(aux->drm_dev, "status not set after read payload table status %d\n",
+			    status);
+		ret = -EINVAL;
+		goto fail;
+	}
+	ret = 0;
+fail:
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_dpcd_write_payload);
+
+/**
+ * drm_dp_dpcd_clear_payload() - Clear the entire VC Payload ID table
+ * @aux: DisplayPort AUX channel
+ *
+ * Clear the entire VC Payload ID table.
+ *
+ * Returns: 0 on success, negative error code on errors.
+ */
+int drm_dp_dpcd_clear_payload(struct drm_dp_aux *aux)
+{
+	return drm_dp_dpcd_write_payload(aux, 0, 0, 0x3f);
+}
+EXPORT_SYMBOL(drm_dp_dpcd_clear_payload);
+
+/**
+ * drm_dp_dpcd_poll_act_handled() - Poll for ACT handled status
+ * @aux: DisplayPort AUX channel
+ * @timeout_ms: Timeout in ms
+ *
+ * Try waiting for the sink to finish updating its payload table by polling for
+ * the ACT handled bit of DP_PAYLOAD_TABLE_UPDATE_STATUS for up to @timeout_ms
+ * milliseconds, defaulting to 3000 ms if 0.
+ *
+ * Returns:
+ * 0 if the ACT was handled in time, negative error code on failure.
+ */
+int drm_dp_dpcd_poll_act_handled(struct drm_dp_aux *aux, int timeout_ms)
+{
+	int ret, status;
+
+	/* default to 3 seconds, this is arbitrary */
+	timeout_ms = timeout_ms ?: 3000;
+
+	ret = readx_poll_timeout(read_payload_update_status, aux, status,
+				 status & DP_PAYLOAD_ACT_HANDLED || status < 0,
+				 200, timeout_ms * USEC_PER_MSEC);
+	if (ret < 0 && status >= 0) {
+		drm_err(aux->drm_dev, "Failed to get ACT after %d ms, last status: %02x\n",
+			timeout_ms, status);
+		return -EINVAL;
+	} else if (status < 0) {
+		/*
+		 * Failure here isn't unexpected - the hub may have
+		 * just been unplugged
+		 */
+		drm_dbg_kms(aux->drm_dev, "Failed to read payload table status: %d\n", status);
+		return status;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_dpcd_poll_act_handled);
+
 static bool is_edid_digital_input_dp(const struct drm_edid *drm_edid)
 {
 	/* FIXME: get rid of drm_edid_raw() */
@@ -1858,6 +2014,9 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 	struct drm_dp_aux_msg msg;
 	int err = 0;
 
+	if (aux->powered_down)
+		return -EBUSY;
+
 	dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES);
 
 	memset(&msg, 0, sizeof(msg));
@@ -2078,7 +2237,7 @@ EXPORT_SYMBOL(drm_dp_aux_init);
  * drm_dp_aux_register() in &drm_connector_funcs.late_register, and likewise to
  * call drm_dp_aux_unregister() in &drm_connector_funcs.early_unregister.
  * Functions which don't follow this will likely Oops when
- * %CONFIG_DRM_DP_AUX_CHARDEV is enabled.
+ * %CONFIG_DRM_DISPLAY_DP_AUX_CHARDEV is enabled.
  *
  * For devices where the AUX channel is a device that exists independently of
  * the &drm_device that uses it, such as SoCs and bridge devices, it is
@@ -2246,6 +2405,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
 	{ OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
 	/* Synaptics DP1.4 MST hubs require DSC for some modes on which it applies HBLANK expansion. */
 	{ OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
+	/* MediaTek panels (at least in U3224KBA) require DSC for modes with a short HBLANK on UHBR links. */
+	{ OUI(0x00, 0x0C, 0xE7), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
 	/* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low DP_MAX_LINK_RATE */
 	{ OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false, BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) },
 };
@@ -2290,6 +2451,31 @@ drm_dp_get_quirks(const struct drm_dp_dpcd_ident *ident, bool is_branch)
 #undef DEVICE_ID_ANY
 #undef DEVICE_ID
 
+static int drm_dp_read_ident(struct drm_dp_aux *aux, unsigned int offset,
+			     struct drm_dp_dpcd_ident *ident)
+{
+	int ret;
+
+	ret = drm_dp_dpcd_read(aux, offset, ident, sizeof(*ident));
+
+	return ret < 0 ? ret : 0;
+}
+
+static void drm_dp_dump_desc(struct drm_dp_aux *aux,
+			     const char *device_name, const struct drm_dp_desc *desc)
+{
+	const struct drm_dp_dpcd_ident *ident = &desc->ident;
+
+	drm_dbg_kms(aux->drm_dev,
+		    "%s: %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d quirks 0x%04x\n",
+		    aux->name, device_name,
+		    (int)sizeof(ident->oui), ident->oui,
+		    (int)strnlen(ident->device_id, sizeof(ident->device_id)), ident->device_id,
+		    ident->hw_rev >> 4, ident->hw_rev & 0xf,
+		    ident->sw_major_rev, ident->sw_minor_rev,
+		    desc->quirks);
+}
+
 /**
  * drm_dp_read_desc - read sink/branch descriptor from DPCD
  * @aux: DisplayPort AUX channel
@@ -2306,28 +2492,49 @@ int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
 {
 	struct drm_dp_dpcd_ident *ident = &desc->ident;
 	unsigned int offset = is_branch ? DP_BRANCH_OUI : DP_SINK_OUI;
-	int ret, dev_id_len;
+	int ret;
 
-	ret = drm_dp_dpcd_read(aux, offset, ident, sizeof(*ident));
+	ret = drm_dp_read_ident(aux, offset, ident);
 	if (ret < 0)
 		return ret;
 
 	desc->quirks = drm_dp_get_quirks(ident, is_branch);
 
-	dev_id_len = strnlen(ident->device_id, sizeof(ident->device_id));
-
-	drm_dbg_kms(aux->drm_dev,
-		    "%s: DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d quirks 0x%04x\n",
-		    aux->name, is_branch ? "branch" : "sink",
-		    (int)sizeof(ident->oui), ident->oui, dev_id_len,
-		    ident->device_id, ident->hw_rev >> 4, ident->hw_rev & 0xf,
-		    ident->sw_major_rev, ident->sw_minor_rev, desc->quirks);
+	drm_dp_dump_desc(aux, is_branch ? "DP branch" : "DP sink", desc);
 
 	return 0;
 }
 EXPORT_SYMBOL(drm_dp_read_desc);
 
 /**
+ * drm_dp_dump_lttpr_desc - read and dump the DPCD descriptor for an LTTPR PHY
+ * @aux: DisplayPort AUX channel
+ * @dp_phy: LTTPR PHY instance
+ *
+ * Read the DPCD LTTPR PHY descriptor for @dp_phy and print a debug message
+ * with its details to dmesg.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int drm_dp_dump_lttpr_desc(struct drm_dp_aux *aux, enum drm_dp_phy dp_phy)
+{
+	struct drm_dp_desc desc = {};
+	int ret;
+
+	if (drm_WARN_ON(aux->drm_dev, dp_phy < DP_PHY_LTTPR1 || dp_phy > DP_MAX_LTTPR_COUNT))
+		return -EINVAL;
+
+	ret = drm_dp_read_ident(aux, DP_OUI_PHY_REPEATER(dp_phy), &desc.ident);
+	if (ret < 0)
+		return ret;
+
+	drm_dp_dump_desc(aux, drm_dp_phy_name(dp_phy), &desc);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_dump_lttpr_desc);
+
+/**
  * drm_dp_dsc_sink_bpp_incr() - Get bits per pixel increment
  * @dsc_dpcd: DSC capabilities from DPCD
  *
@@ -2337,7 +2544,7 @@ u8 drm_dp_dsc_sink_bpp_incr(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
 {
 	u8 bpp_increment_dpcd = dsc_dpcd[DP_DSC_BITS_PER_PIXEL_INC - DP_DSC_SUPPORT];
 
-	switch (bpp_increment_dpcd) {
+	switch (bpp_increment_dpcd & DP_DSC_BITS_PER_PIXEL_MASK) {
 	case DP_DSC_BITS_PER_PIXEL_1_16:
 		return 16;
 	case DP_DSC_BITS_PER_PIXEL_1_8:
@@ -2897,25 +3104,156 @@ static const char *dp_content_type_get_name(enum dp_content_type content_type)
 	}
 }
 
-void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
-			const struct drm_dp_vsc_sdp *vsc)
+void drm_dp_vsc_sdp_log(struct drm_printer *p, const struct drm_dp_vsc_sdp *vsc)
 {
-#define DP_SDP_LOG(fmt, ...) dev_printk(level, dev, fmt, ##__VA_ARGS__)
-	DP_SDP_LOG("DP SDP: %s, revision %u, length %u\n", "VSC",
+	drm_printf(p, "DP SDP: VSC, revision %u, length %u\n",
 		   vsc->revision, vsc->length);
-	DP_SDP_LOG("    pixelformat: %s\n",
+	drm_printf(p, "    pixelformat: %s\n",
 		   dp_pixelformat_get_name(vsc->pixelformat));
-	DP_SDP_LOG("    colorimetry: %s\n",
+	drm_printf(p, "    colorimetry: %s\n",
 		   dp_colorimetry_get_name(vsc->pixelformat, vsc->colorimetry));
-	DP_SDP_LOG("    bpc: %u\n", vsc->bpc);
-	DP_SDP_LOG("    dynamic range: %s\n",
+	drm_printf(p, "    bpc: %u\n", vsc->bpc);
+	drm_printf(p, "    dynamic range: %s\n",
 		   dp_dynamic_range_get_name(vsc->dynamic_range));
-	DP_SDP_LOG("    content type: %s\n",
+	drm_printf(p, "    content type: %s\n",
 		   dp_content_type_get_name(vsc->content_type));
-#undef DP_SDP_LOG
 }
 EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
 
+void drm_dp_as_sdp_log(struct drm_printer *p, const struct drm_dp_as_sdp *as_sdp)
+{
+	drm_printf(p, "DP SDP: AS_SDP, revision %u, length %u\n",
+		   as_sdp->revision, as_sdp->length);
+	drm_printf(p, "    vtotal: %d\n", as_sdp->vtotal);
+	drm_printf(p, "    target_rr: %d\n", as_sdp->target_rr);
+	drm_printf(p, "    duration_incr_ms: %d\n", as_sdp->duration_incr_ms);
+	drm_printf(p, "    duration_decr_ms: %d\n", as_sdp->duration_decr_ms);
+	drm_printf(p, "    operation_mode: %d\n", as_sdp->mode);
+}
+EXPORT_SYMBOL(drm_dp_as_sdp_log);
+
+/**
+ * drm_dp_as_sdp_supported() - check if adaptive sync sdp is supported
+ * @aux: DisplayPort AUX channel
+ * @dpcd: DisplayPort configuration data
+ *
+ * Returns true if adaptive sync sdp is supported, else returns false
+ */
+bool drm_dp_as_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 rx_feature;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_13)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1,
+			      &rx_feature) != 1) {
+		drm_dbg_dp(aux->drm_dev,
+			   "Failed to read DP_DPRX_FEATURE_ENUMERATION_LIST_CONT_1\n");
+		return false;
+	}
+
+	return (rx_feature & DP_ADAPTIVE_SYNC_SDP_SUPPORTED);
+}
+EXPORT_SYMBOL(drm_dp_as_sdp_supported);
+
+/**
+ * drm_dp_vsc_sdp_supported() - check if vsc sdp is supported
+ * @aux: DisplayPort AUX channel
+ * @dpcd: DisplayPort configuration data
+ *
+ * Returns true if vsc sdp is supported, else returns false
+ */
+bool drm_dp_vsc_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	u8 rx_feature;
+
+	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_13)
+		return false;
+
+	if (drm_dp_dpcd_readb(aux, DP_DPRX_FEATURE_ENUMERATION_LIST, &rx_feature) != 1) {
+		drm_dbg_dp(aux->drm_dev, "failed to read DP_DPRX_FEATURE_ENUMERATION_LIST\n");
+		return false;
+	}
+
+	return (rx_feature & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED);
+}
+EXPORT_SYMBOL(drm_dp_vsc_sdp_supported);
+
+/**
+ * drm_dp_vsc_sdp_pack() - pack a given vsc sdp into generic dp_sdp
+ * @vsc: vsc sdp initialized according to its purpose as defined in
+ *       table 2-118 - table 2-120 in DP 1.4a specification
+ * @sdp: valid handle to the generic dp_sdp which will be packed
+ *
+ * Returns length of sdp on success and error code on failure
+ */
+ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
+			    struct dp_sdp *sdp)
+{
+	size_t length = sizeof(struct dp_sdp);
+
+	memset(sdp, 0, sizeof(struct dp_sdp));
+
+	/*
+	 * Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
+	 * VSC SDP Header Bytes
+	 */
+	sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
+	sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
+	sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
+	sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
+
+	if (vsc->revision == 0x6) {
+		sdp->db[0] = 1;
+		sdp->db[3] = 1;
+	}
+
+	/*
+	 * Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
+	 * Format as per DP 1.4a spec and DP 2.0 respectively.
+	 */
+	if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
+		goto out;
+
+	/* VSC SDP Payload for DB16 through DB18 */
+	/* Pixel Encoding and Colorimetry Formats  */
+	sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
+	sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
+
+	switch (vsc->bpc) {
+	case 6:
+		/* 6bpc: 0x0 */
+		break;
+	case 8:
+		sdp->db[17] = 0x1; /* DB17[3:0] */
+		break;
+	case 10:
+		sdp->db[17] = 0x2;
+		break;
+	case 12:
+		sdp->db[17] = 0x3;
+		break;
+	case 16:
+		sdp->db[17] = 0x4;
+		break;
+	default:
+		WARN(1, "Missing case %d\n", vsc->bpc);
+		return -EINVAL;
+	}
+
+	/* Dynamic Range and Component Bit Depth */
+	if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
+		sdp->db[17] |= 0x80;  /* DB17[7] */
+
+	/* Content Type */
+	sdp->db[18] = vsc->content_type & 0x7;
+
+out:
+	return length;
+}
+EXPORT_SYMBOL(drm_dp_vsc_sdp_pack);
+
 /**
  * drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
  * @dpcd: DisplayPort configuration data
@@ -3982,6 +4320,13 @@ int drm_dp_bw_overhead(int lane_count, int hactive,
 	u32 overhead = 1000000;
 	int symbol_cycles;
 
+	if (lane_count == 0 || hactive == 0 || bpp_x16 == 0) {
+		DRM_DEBUG_KMS("Invalid BW overhead params: lane_count %d, hactive %d, bpp_x16 " FXP_Q4_FMT "\n",
+			      lane_count, hactive,
+			      FXP_Q4_ARGS(bpp_x16));
+		return 0;
+	}
+
 	/*
 	 * DP Standard v2.1 2.6.4.1
 	 * SSC downspread and ref clock variation margin:
@@ -4058,3 +4403,33 @@ int drm_dp_bw_channel_coding_efficiency(bool is_uhbr)
 		return 800000;
 }
 EXPORT_SYMBOL(drm_dp_bw_channel_coding_efficiency);
+
+/**
+ * drm_dp_max_dprx_data_rate - Get the max data bandwidth of a DPRX sink
+ * @max_link_rate: max DPRX link rate in 10kbps units
+ * @max_lanes: max DPRX lane count
+ *
+ * Given a link rate and lanes, get the data bandwidth.
+ *
+ * Data bandwidth is the actual payload rate, which depends on the data
+ * bandwidth efficiency and the link rate.
+ *
+ * Note that protocol layers above the DPRX link level considered here can
+ * further limit the maximum data rate. Such layers are the MST topology (with
+ * limits on the link between the source and first branch device as well as on
+ * the whole MST path until the DPRX link) and (Thunderbolt) DP tunnels -
+ * which in turn can encapsulate an MST link with its own limit - with each
+ * SST or MST encapsulated tunnel sharing the BW of a tunnel group.
+ *
+ * Returns the maximum data rate in kBps units.
+ */
+int drm_dp_max_dprx_data_rate(int max_link_rate, int max_lanes)
+{
+	int ch_coding_efficiency =
+		drm_dp_bw_channel_coding_efficiency(drm_dp_is_uhbr_rate(max_link_rate));
+
+	return DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate * 10 * max_lanes,
+					      ch_coding_efficiency),
+				  1000000 * 8);
+}
+EXPORT_SYMBOL(drm_dp_max_dprx_data_rate);