[PATCH v2] drm/i915/hdcp: switch to drm_dp_dpcd_{read_byte, read_data, write_data}()

[Jani Nikula <jani.nikula@intel.com>]

Switch to the modern DPCD access functions that return negative error
codes on errors, -EIO for incomplete access, and 0 on success.

This simplifies error handling all over the place. Convert the error
logging to use %pe and ERR_PTR() while at it.

Add comments to the read/write places that depend on the functions that
return the number of bytes read/written for incomplete access.

v2: return length from get_receiver_id_list_rx_info() (Sashiko)

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_hdcp.c | 176 +++++++++----------
 1 file changed, 88 insertions(+), 88 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
index 14ed0ea22dd3..566a921d18a1 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
@@ -60,16 +60,15 @@ int intel_dp_hdcp_write_an_aksv(struct intel_digital_port *dig_port,
 {
 	struct intel_display *display = to_intel_display(dig_port);
 	u8 aksv[DRM_HDCP_KSV_LEN] = {};
-	ssize_t dpcd_ret;
+	int ret;
 
 	/* Output An first, that's easy */
-	dpcd_ret = drm_dp_dpcd_write(&dig_port->dp.aux, DP_AUX_HDCP_AN,
+	ret = drm_dp_dpcd_write_data(&dig_port->dp.aux, DP_AUX_HDCP_AN,
 				     an, DRM_HDCP_AN_LEN);
-	if (dpcd_ret != DRM_HDCP_AN_LEN) {
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Failed to write An over DP/AUX (%zd)\n",
-			    dpcd_ret);
-		return dpcd_ret >= 0 ? -EIO : dpcd_ret;
+			    "Failed to write An over DP/AUX (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
 
 	/*
@@ -79,14 +78,14 @@ int intel_dp_hdcp_write_an_aksv(struct intel_digital_port *dig_port,
 	 * the destination address which will tickle the hardware to output the
 	 * Aksv on our behalf after the header is sent.
 	 */
-	dpcd_ret = drm_dp_dpcd_write(&dig_port->dp.aux, DP_AUX_HDCP_AKSV,
+	ret = drm_dp_dpcd_write_data(&dig_port->dp.aux, DP_AUX_HDCP_AKSV,
 				     aksv, DRM_HDCP_KSV_LEN);
-	if (dpcd_ret != DRM_HDCP_KSV_LEN) {
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Failed to write Aksv over DP/AUX (%zd)\n",
-			    dpcd_ret);
-		return dpcd_ret >= 0 ? -EIO : dpcd_ret;
+			    "Failed to write Aksv over DP/AUX (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
+
 	return 0;
 }
 
@@ -94,15 +93,16 @@ static int intel_dp_hdcp_read_bksv(struct intel_digital_port *dig_port,
 				   u8 *bksv)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
+	int ret;
 
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux, DP_AUX_HDCP_BKSV, bksv,
-			       DRM_HDCP_KSV_LEN);
-	if (ret != DRM_HDCP_KSV_LEN) {
+	ret = drm_dp_dpcd_read_data(&dig_port->dp.aux, DP_AUX_HDCP_BKSV, bksv,
+				    DRM_HDCP_KSV_LEN);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read Bksv from DP/AUX failed (%zd)\n", ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read Bksv from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
+
 	return 0;
 }
 
@@ -110,20 +110,21 @@ static int intel_dp_hdcp_read_bstatus(struct intel_digital_port *dig_port,
 				      u8 *bstatus)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
+	int ret;
 
 	/*
 	 * For some reason the HDMI and DP HDCP specs call this register
 	 * definition by different names. In the HDMI spec, it's called BSTATUS,
 	 * but in DP it's called BINFO.
 	 */
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux, DP_AUX_HDCP_BINFO,
-			       bstatus, DRM_HDCP_BSTATUS_LEN);
-	if (ret != DRM_HDCP_BSTATUS_LEN) {
+	ret = drm_dp_dpcd_read_data(&dig_port->dp.aux, DP_AUX_HDCP_BINFO,
+				    bstatus, DRM_HDCP_BSTATUS_LEN);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read bstatus from DP/AUX failed (%zd)\n", ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read bstatus from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
+
 	return 0;
 }
 
@@ -132,14 +133,13 @@ int intel_dp_hdcp_read_bcaps(struct drm_dp_aux *aux,
 			     struct intel_display *display,
 			     u8 *bcaps)
 {
-	ssize_t ret;
+	int ret;
 
-	ret = drm_dp_dpcd_read(aux, DP_AUX_HDCP_BCAPS,
-			       bcaps, 1);
-	if (ret != 1) {
+	ret = drm_dp_dpcd_read_byte(aux, DP_AUX_HDCP_BCAPS, bcaps);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read bcaps from DP/AUX failed (%zd)\n", ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read bcaps from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
 
 	return 0;
@@ -166,16 +166,16 @@ int intel_dp_hdcp_read_ri_prime(struct intel_digital_port *dig_port,
 				u8 *ri_prime)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
+	int ret;
 
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux, DP_AUX_HDCP_RI_PRIME,
-			       ri_prime, DRM_HDCP_RI_LEN);
-	if (ret != DRM_HDCP_RI_LEN) {
+	ret = drm_dp_dpcd_read_data(&dig_port->dp.aux, DP_AUX_HDCP_RI_PRIME,
+				    ri_prime, DRM_HDCP_RI_LEN);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read Ri' from DP/AUX failed (%zd)\n",
-			    ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read Ri' from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
+
 	return 0;
 }
 
@@ -184,17 +184,18 @@ int intel_dp_hdcp_read_ksv_ready(struct intel_digital_port *dig_port,
 				 bool *ksv_ready)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
 	u8 bstatus;
+	int ret;
 
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux, DP_AUX_HDCP_BSTATUS,
-			       &bstatus, 1);
-	if (ret != 1) {
+	ret = drm_dp_dpcd_read_byte(&dig_port->dp.aux, DP_AUX_HDCP_BSTATUS,
+				    &bstatus);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read bstatus from DP/AUX failed (%zd)\n", ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read bstatus from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
 	*ksv_ready = bstatus & DP_BSTATUS_READY;
+
 	return 0;
 }
 
@@ -203,23 +204,24 @@ int intel_dp_hdcp_read_ksv_fifo(struct intel_digital_port *dig_port,
 				int num_downstream, u8 *ksv_fifo)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
+	int ret;
 	int i;
 
 	/* KSV list is read via 15 byte window (3 entries @ 5 bytes each) */
 	for (i = 0; i < num_downstream; i += 3) {
 		size_t len = min(num_downstream - i, 3) * DRM_HDCP_KSV_LEN;
-		ret = drm_dp_dpcd_read(&dig_port->dp.aux,
-				       DP_AUX_HDCP_KSV_FIFO,
-				       ksv_fifo + i * DRM_HDCP_KSV_LEN,
-				       len);
-		if (ret != len) {
+		ret = drm_dp_dpcd_read_data(&dig_port->dp.aux,
+					    DP_AUX_HDCP_KSV_FIFO,
+					    ksv_fifo + i * DRM_HDCP_KSV_LEN,
+					    len);
+		if (ret < 0) {
 			drm_dbg_kms(display->drm,
-				    "Read ksv[%d] from DP/AUX failed (%zd)\n",
-				    i, ret);
-			return ret >= 0 ? -EIO : ret;
+				    "Read ksv[%d] from DP/AUX failed (%pe)\n",
+				    i, ERR_PTR(ret));
+			return ret;
 		}
 	}
+
 	return 0;
 }
 
@@ -228,19 +230,19 @@ int intel_dp_hdcp_read_v_prime_part(struct intel_digital_port *dig_port,
 				    int i, u32 *part)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
+	int ret;
 
 	if (i >= DRM_HDCP_V_PRIME_NUM_PARTS)
 		return -EINVAL;
 
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux,
-			       DP_AUX_HDCP_V_PRIME(i), part,
-			       DRM_HDCP_V_PRIME_PART_LEN);
-	if (ret != DRM_HDCP_V_PRIME_PART_LEN) {
+	ret = drm_dp_dpcd_read_data(&dig_port->dp.aux, DP_AUX_HDCP_V_PRIME(i), part,
+				    DRM_HDCP_V_PRIME_PART_LEN);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read v'[%d] from DP/AUX failed (%zd)\n", i, ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read v'[%d] from DP/AUX failed (%pe)\n", i, ERR_PTR(ret));
+		return ret;
 	}
+
 	return 0;
 }
 
@@ -258,14 +260,13 @@ bool intel_dp_hdcp_check_link(struct intel_digital_port *dig_port,
 			      struct intel_connector *connector)
 {
 	struct intel_display *display = to_intel_display(dig_port);
-	ssize_t ret;
 	u8 bstatus;
+	int ret;
 
-	ret = drm_dp_dpcd_read(&dig_port->dp.aux, DP_AUX_HDCP_BSTATUS,
-			       &bstatus, 1);
-	if (ret != 1) {
+	ret = drm_dp_dpcd_read_byte(&dig_port->dp.aux, DP_AUX_HDCP_BSTATUS, &bstatus);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read bstatus from DP/AUX failed (%zd)\n", ret);
+			    "Read bstatus from DP/AUX failed (%pe)\n", ERR_PTR(ret));
 		return false;
 	}
 
@@ -346,15 +347,14 @@ intel_dp_hdcp2_read_rx_status(struct intel_connector *connector,
 	struct intel_display *display = to_intel_display(connector);
 	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
 	struct drm_dp_aux *aux = &dig_port->dp.aux;
-	ssize_t ret;
+	int ret;
 
-	ret = drm_dp_dpcd_read(aux,
-			       DP_HDCP_2_2_REG_RXSTATUS_OFFSET, rx_status,
-			       HDCP_2_2_DP_RXSTATUS_LEN);
-	if (ret != HDCP_2_2_DP_RXSTATUS_LEN) {
+	ret = drm_dp_dpcd_read_data(aux, DP_HDCP_2_2_REG_RXSTATUS_OFFSET, rx_status,
+				    HDCP_2_2_DP_RXSTATUS_LEN);
+	if (ret < 0) {
 		drm_dbg_kms(display->drm,
-			    "Read bstatus from DP/AUX failed (%zd)\n", ret);
-		return ret >= 0 ? -EIO : ret;
+			    "Read bstatus from DP/AUX failed (%pe)\n", ERR_PTR(ret));
+		return ret;
 	}
 
 	return 0;
@@ -474,8 +474,8 @@ int intel_dp_hdcp2_write_msg(struct intel_connector *connector,
 		len = bytes_to_write > DP_AUX_MAX_PAYLOAD_BYTES ?
 				DP_AUX_MAX_PAYLOAD_BYTES : bytes_to_write;
 
-		ret = drm_dp_dpcd_write(aux,
-					offset, (void *)byte, len);
+		/* Note: This may return < len for partial writes. */
+		ret = drm_dp_dpcd_write(aux, offset, byte, len);
 		if (ret < 0)
 			return ret;
 
@@ -487,20 +487,20 @@ int intel_dp_hdcp2_write_msg(struct intel_connector *connector,
 	return size;
 }
 
+/* return number of bytes read on success */
 static
 ssize_t get_receiver_id_list_rx_info(struct intel_connector *connector,
 				     u32 *dev_cnt, u8 *byte)
 {
 	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
 	struct drm_dp_aux *aux = &dig_port->dp.aux;
-	ssize_t ret;
 	u8 *rx_info = byte;
+	int ret;
 
-	ret = drm_dp_dpcd_read(aux,
-			       DP_HDCP_2_2_REG_RXINFO_OFFSET,
-			       (void *)rx_info, HDCP_2_2_RXINFO_LEN);
-	if (ret != HDCP_2_2_RXINFO_LEN)
-		return ret >= 0 ? -EIO : ret;
+	ret = drm_dp_dpcd_read_data(aux, DP_HDCP_2_2_REG_RXINFO_OFFSET,
+				    rx_info, HDCP_2_2_RXINFO_LEN);
+	if (ret < 0)
+		return ret;
 
 	*dev_cnt = (HDCP_2_2_DEV_COUNT_HI(rx_info[0]) << 4 |
 		   HDCP_2_2_DEV_COUNT_LO(rx_info[1]));
@@ -508,7 +508,7 @@ ssize_t get_receiver_id_list_rx_info(struct intel_connector *connector,
 	if (*dev_cnt > HDCP_2_2_MAX_DEVICE_COUNT)
 		*dev_cnt = HDCP_2_2_MAX_DEVICE_COUNT;
 
-	return ret;
+	return HDCP_2_2_RXINFO_LEN;
 }
 
 static
@@ -566,11 +566,11 @@ int intel_dp_hdcp2_read_msg(struct intel_connector *connector,
 					       hdcp2_msg_data->msg_read_timeout);
 		}
 
-		ret = drm_dp_dpcd_read(aux, offset,
-				       (void *)byte, len);
+		/* Note: This may return < len for partial reads. */
+		ret = drm_dp_dpcd_read(aux, offset, byte, len);
 		if (ret < 0) {
-			drm_dbg_kms(display->drm, "msg_id %d, ret %zd\n",
-				    msg_id, ret);
+			drm_dbg_kms(display->drm, "msg_id %d, ret %pe\n",
+				    msg_id, ERR_PTR(ret));
 			return ret;
 		}
 
@@ -660,11 +660,11 @@ int _intel_dp_hdcp2_get_capability(struct drm_dp_aux *aux,
 	 * declare a monitor not capable of HDCP 2.2.
 	 */
 	for (i = 0; i < 3; i++) {
-		ret = drm_dp_dpcd_read(aux,
-				       DP_HDCP_2_2_REG_RX_CAPS_OFFSET,
-				       rx_caps, HDCP_2_2_RXCAPS_LEN);
-		if (ret != HDCP_2_2_RXCAPS_LEN)
-			return ret >= 0 ? -EIO : ret;
+		ret = drm_dp_dpcd_read_data(aux,
+					    DP_HDCP_2_2_REG_RX_CAPS_OFFSET,
+					    rx_caps, HDCP_2_2_RXCAPS_LEN);
+		if (ret < 0)
+			return ret;
 
 		if (rx_caps[0] == HDCP_2_2_RX_CAPS_VERSION_VAL &&
 		    HDCP_2_2_DP_HDCP_CAPABLE(rx_caps[2])) {
-- 
2.47.3