All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ramalingam C <ramalingam.c@intel.com>
To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	daniel.vetter@ffwll.ch, tomas.winkler@intel.com,
	uma.shankar@intel.com
Subject: [PATCH v12 15/38] drm/i915: Implement the HDCP2.2 support for DP
Date: Sat,  9 Feb 2019 12:42:44 +0530	[thread overview]
Message-ID: <1549696387-28268-16-git-send-email-ramalingam.c@intel.com> (raw)
In-Reply-To: <1549696387-28268-1-git-send-email-ramalingam.c@intel.com>

Implements the DP adaptation specific HDCP2.2 functions.

These functions perform the DPCD read and write for communicating the
HDCP2.2 auth message back and forth.

v2:
  wait for cp_irq is merged with this patch. Rebased.
v3:
  wait_queue is used for wait for cp_irq [Chris Wilson]
v4:
  Style fixed.
  %s/PARING/PAIRING
  Few style fixes [Uma]
v5:
  Lookup table for DP HDCP2.2 msg details [Daniel].
  Extra lines are removed.
v6: Rebased.
v7:
  Fixed some regression introduced at v5. [Ankit]
  Macro HDCP_2_2_RX_CAPS_VERSION_VAL is reused [Uma]
  Converted a function to inline [Uma]
  %s/uintxx_t/uxx
v8:
  Error due to the sinks are reported as DEBUG logs.
  Adjust to the new mei interface.
v9:
  ARRAY_SIZE for no of array members [Jon & Daniel]
  return of the wait_for_cp_irq is made as void [Daniel]
  Wait for HDCP2.2 msg is done based on polling the reg bit than
    CP_IRQ based. [Daniel]
  hdcp adaptation is added as a const in the hdcp_shim [Daniel]
v10:
  config_stream_type is redefined [Daniel]
  DP Errata specific defines are moved into intel_dp.c.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Ankit K Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 333 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 333 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 9f73a4239574..e9fe25f21200 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5847,6 +5847,333 @@ int intel_dp_hdcp_capable(struct intel_digital_port *intel_dig_port,
 	return 0;
 }
 
+struct hdcp2_dp_errata_stream_type {
+	u8	msg_id;
+	u8	stream_type;
+} __packed;
+
+static struct hdcp2_dp_msg_data {
+	u8 msg_id;
+	u32 offset;
+	bool msg_detectable;
+	u32 timeout;
+	u32 timeout2; /* Added for non_paired situation */
+	} hdcp2_msg_data[] = {
+		{HDCP_2_2_AKE_INIT, DP_HDCP_2_2_AKE_INIT_OFFSET, false, 0, 0},
+		{HDCP_2_2_AKE_SEND_CERT, DP_HDCP_2_2_AKE_SEND_CERT_OFFSET,
+				false, HDCP_2_2_CERT_TIMEOUT_MS, 0},
+		{HDCP_2_2_AKE_NO_STORED_KM, DP_HDCP_2_2_AKE_NO_STORED_KM_OFFSET,
+				false, 0, 0},
+		{HDCP_2_2_AKE_STORED_KM, DP_HDCP_2_2_AKE_STORED_KM_OFFSET,
+				false, 0, 0},
+		{HDCP_2_2_AKE_SEND_HPRIME, DP_HDCP_2_2_AKE_SEND_HPRIME_OFFSET,
+				true, HDCP_2_2_HPRIME_PAIRED_TIMEOUT_MS,
+				HDCP_2_2_HPRIME_NO_PAIRED_TIMEOUT_MS},
+		{HDCP_2_2_AKE_SEND_PAIRING_INFO,
+				DP_HDCP_2_2_AKE_SEND_PAIRING_INFO_OFFSET, true,
+				HDCP_2_2_PAIRING_TIMEOUT_MS, 0},
+		{HDCP_2_2_LC_INIT, DP_HDCP_2_2_LC_INIT_OFFSET, false, 0, 0},
+		{HDCP_2_2_LC_SEND_LPRIME, DP_HDCP_2_2_LC_SEND_LPRIME_OFFSET,
+				false, HDCP_2_2_DP_LPRIME_TIMEOUT_MS, 0},
+		{HDCP_2_2_SKE_SEND_EKS, DP_HDCP_2_2_SKE_SEND_EKS_OFFSET, false,
+				0, 0},
+		{HDCP_2_2_REP_SEND_RECVID_LIST,
+				DP_HDCP_2_2_REP_SEND_RECVID_LIST_OFFSET, true,
+				HDCP_2_2_RECVID_LIST_TIMEOUT_MS, 0},
+		{HDCP_2_2_REP_SEND_ACK, DP_HDCP_2_2_REP_SEND_ACK_OFFSET, false,
+				0, 0},
+		{HDCP_2_2_REP_STREAM_MANAGE,
+				DP_HDCP_2_2_REP_STREAM_MANAGE_OFFSET, false,
+				0, 0},
+		{HDCP_2_2_REP_STREAM_READY, DP_HDCP_2_2_REP_STREAM_READY_OFFSET,
+				false, HDCP_2_2_STREAM_READY_TIMEOUT_MS, 0},
+/* local define to shovel this through the write_2_2 interface */
+#define HDCP_2_2_ERRATA_DP_STREAM_TYPE	50
+		{HDCP_2_2_ERRATA_DP_STREAM_TYPE,
+				DP_HDCP_2_2_REG_STREAM_TYPE_OFFSET, false,
+				0, 0},
+		};
+
+static inline
+int intel_dp_hdcp2_read_rx_status(struct intel_digital_port *intel_dig_port,
+				  u8 *rx_status)
+{
+	ssize_t ret;
+
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux,
+			       DP_HDCP_2_2_REG_RXSTATUS_OFFSET, rx_status,
+			       HDCP_2_2_DP_RXSTATUS_LEN);
+	if (ret != HDCP_2_2_DP_RXSTATUS_LEN) {
+		DRM_DEBUG_KMS("Read bstatus from DP/AUX failed (%zd)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+
+	return 0;
+}
+
+static
+int hdcp2_detect_msg_availability(struct intel_digital_port *intel_dig_port,
+				  u8 msg_id, bool *msg_ready)
+{
+	u8 rx_status;
+	int ret;
+
+	*msg_ready = false;
+	ret = intel_dp_hdcp2_read_rx_status(intel_dig_port, &rx_status);
+	if (ret < 0)
+		return ret;
+
+	switch (msg_id) {
+	case HDCP_2_2_AKE_SEND_HPRIME:
+		if (HDCP_2_2_DP_RXSTATUS_H_PRIME(rx_status))
+			*msg_ready = true;
+		break;
+	case HDCP_2_2_AKE_SEND_PAIRING_INFO:
+		if (HDCP_2_2_DP_RXSTATUS_PAIRING(rx_status))
+			*msg_ready = true;
+		break;
+	case HDCP_2_2_REP_SEND_RECVID_LIST:
+		if (HDCP_2_2_DP_RXSTATUS_READY(rx_status))
+			*msg_ready = true;
+		break;
+	default:
+		DRM_ERROR("Unidentified msg_id: %d\n", msg_id);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static ssize_t
+intel_dp_hdcp2_wait_for_msg(struct intel_digital_port *intel_dig_port,
+			    struct hdcp2_dp_msg_data *hdcp2_msg_data)
+{
+	struct intel_dp *dp = &intel_dig_port->dp;
+	struct intel_hdcp *hdcp = &dp->attached_connector->hdcp;
+	u8 msg_id = hdcp2_msg_data->msg_id;
+	int ret, timeout;
+	bool msg_ready = false;
+
+	if (msg_id == HDCP_2_2_AKE_SEND_HPRIME && !hdcp->is_paired)
+		timeout = hdcp2_msg_data->timeout2;
+	else
+		timeout = hdcp2_msg_data->timeout;
+
+	/*
+	 * There is no way to detect the CERT, LPRIME and STREAM_READY
+	 * availability. So Wait for timeout and read the msg.
+	 */
+	if (!hdcp2_msg_data->msg_detectable) {
+		mdelay(timeout);
+		ret = 0;
+	} else {
+		/* TODO: In case if you need to wait on CP_IRQ, do it here */
+		ret = __wait_for(ret =
+				 hdcp2_detect_msg_availability(intel_dig_port,
+							       msg_id,
+							       &msg_ready),
+				 !ret && msg_ready, timeout * 1000,
+				 1000, 5 * 1000);
+
+		if (!msg_ready)
+			ret = -ETIMEDOUT;
+	}
+
+	if (ret)
+		DRM_DEBUG_KMS("msg_id %d, ret %d, timeout(mSec): %d\n",
+			      hdcp2_msg_data->msg_id, ret, timeout);
+
+	return ret;
+}
+
+static struct hdcp2_dp_msg_data *get_hdcp2_dp_msg_data(u8 msg_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hdcp2_msg_data); i++)
+		if (hdcp2_msg_data[i].msg_id == msg_id)
+			return &hdcp2_msg_data[i];
+
+	return NULL;
+}
+
+static
+int intel_dp_hdcp2_write_msg(struct intel_digital_port *intel_dig_port,
+			     void *buf, size_t size)
+{
+	unsigned int offset;
+	u8 *byte = buf;
+	ssize_t ret, bytes_to_write, len;
+	struct hdcp2_dp_msg_data *hdcp2_msg_data;
+
+	hdcp2_msg_data = get_hdcp2_dp_msg_data(*byte);
+	if (!hdcp2_msg_data)
+		return -EINVAL;
+
+	offset = hdcp2_msg_data->offset;
+
+	/* No msg_id in DP HDCP2.2 msgs */
+	bytes_to_write = size - 1;
+	byte++;
+
+	while (bytes_to_write) {
+		len = bytes_to_write > DP_AUX_MAX_PAYLOAD_BYTES ?
+				DP_AUX_MAX_PAYLOAD_BYTES : bytes_to_write;
+
+		ret = drm_dp_dpcd_write(&intel_dig_port->dp.aux,
+					offset, (void *)byte, len);
+		if (ret < 0)
+			return ret;
+
+		bytes_to_write -= ret;
+		byte += ret;
+		offset += ret;
+	}
+
+	return size;
+}
+
+static
+ssize_t get_receiver_id_list_size(struct intel_digital_port *intel_dig_port)
+{
+	u8 rx_info[HDCP_2_2_RXINFO_LEN];
+	u32 dev_cnt;
+	ssize_t ret;
+
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.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;
+
+	dev_cnt = (HDCP_2_2_DEV_COUNT_HI(rx_info[0]) << 4 |
+		   HDCP_2_2_DEV_COUNT_LO(rx_info[1]));
+
+	if (dev_cnt > HDCP_2_2_MAX_DEVICE_COUNT)
+		dev_cnt = HDCP_2_2_MAX_DEVICE_COUNT;
+
+	ret = sizeof(struct hdcp2_rep_send_receiverid_list) -
+		HDCP_2_2_RECEIVER_IDS_MAX_LEN +
+		(dev_cnt * HDCP_2_2_RECEIVER_ID_LEN);
+
+	return ret;
+}
+
+static
+int intel_dp_hdcp2_read_msg(struct intel_digital_port *intel_dig_port,
+			    u8 msg_id, void *buf, size_t size)
+{
+	unsigned int offset;
+	u8 *byte = buf;
+	ssize_t ret, bytes_to_recv, len;
+	struct hdcp2_dp_msg_data *hdcp2_msg_data;
+
+	hdcp2_msg_data = get_hdcp2_dp_msg_data(msg_id);
+	if (!hdcp2_msg_data)
+		return -EINVAL;
+	offset = hdcp2_msg_data->offset;
+
+	ret = intel_dp_hdcp2_wait_for_msg(intel_dig_port, hdcp2_msg_data);
+	if (ret < 0)
+		return ret;
+
+	if (msg_id == HDCP_2_2_REP_SEND_RECVID_LIST) {
+		ret = get_receiver_id_list_size(intel_dig_port);
+		if (ret < 0)
+			return ret;
+
+		size = ret;
+	}
+	bytes_to_recv = size - 1;
+
+	/* DP adaptation msgs has no msg_id */
+	byte++;
+
+	while (bytes_to_recv) {
+		len = bytes_to_recv > DP_AUX_MAX_PAYLOAD_BYTES ?
+		      DP_AUX_MAX_PAYLOAD_BYTES : bytes_to_recv;
+
+		ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, offset,
+				       (void *)byte, len);
+		if (ret < 0) {
+			DRM_DEBUG_KMS("msg_id %d, ret %zd\n", msg_id, ret);
+			return ret;
+		}
+
+		bytes_to_recv -= ret;
+		byte += ret;
+		offset += ret;
+	}
+	byte = buf;
+	*byte = msg_id;
+
+	return size;
+}
+
+static
+int intel_dp_hdcp2_config_stream_type(struct intel_digital_port *intel_dig_port,
+				      bool is_repeater, u8 content_type)
+{
+	struct hdcp2_dp_errata_stream_type stream_type_msg;
+
+	if (is_repeater)
+		return 0;
+
+	/*
+	 * Errata for DP: As Stream type is used for encryption, Receiver
+	 * should be communicated with stream type for the decryption of the
+	 * content.
+	 * Repeater will be communicated with stream type as a part of it's
+	 * auth later in time.
+	 */
+	stream_type_msg.msg_id = HDCP_2_2_ERRATA_DP_STREAM_TYPE;
+	stream_type_msg.stream_type = content_type;
+
+	return intel_dp_hdcp2_write_msg(intel_dig_port, &stream_type_msg,
+					sizeof(stream_type_msg));
+}
+
+static
+int intel_dp_hdcp2_check_link(struct intel_digital_port *intel_dig_port)
+{
+	u8 rx_status;
+	int ret;
+
+	ret = intel_dp_hdcp2_read_rx_status(intel_dig_port, &rx_status);
+	if (ret)
+		return ret;
+
+	if (HDCP_2_2_DP_RXSTATUS_REAUTH_REQ(rx_status))
+		ret = HDCP_REAUTH_REQUEST;
+	else if (HDCP_2_2_DP_RXSTATUS_LINK_FAILED(rx_status))
+		ret = HDCP_LINK_INTEGRITY_FAILURE;
+	else if (HDCP_2_2_DP_RXSTATUS_READY(rx_status))
+		ret = HDCP_TOPOLOGY_CHANGE;
+
+	return ret;
+}
+
+static
+int intel_dp_hdcp2_capable(struct intel_digital_port *intel_dig_port,
+			   bool *capable)
+{
+	u8 rx_caps[3];
+	int ret;
+
+	*capable = false;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.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;
+
+	if (rx_caps[0] == HDCP_2_2_RX_CAPS_VERSION_VAL &&
+	    HDCP_2_2_DP_HDCP_CAPABLE(rx_caps[2]))
+		*capable = true;
+
+	return 0;
+}
+
 static const struct intel_hdcp_shim intel_dp_hdcp_shim = {
 	.write_an_aksv = intel_dp_hdcp_write_an_aksv,
 	.read_bksv = intel_dp_hdcp_read_bksv,
@@ -5859,6 +6186,12 @@ static const struct intel_hdcp_shim intel_dp_hdcp_shim = {
 	.toggle_signalling = intel_dp_hdcp_toggle_signalling,
 	.check_link = intel_dp_hdcp_check_link,
 	.hdcp_capable = intel_dp_hdcp_capable,
+	.write_2_2_msg = intel_dp_hdcp2_write_msg,
+	.read_2_2_msg = intel_dp_hdcp2_read_msg,
+	.config_stream_type = intel_dp_hdcp2_config_stream_type,
+	.check_2_2_link = intel_dp_hdcp2_check_link,
+	.hdcp_2_2_capable = intel_dp_hdcp2_capable,
+	.protocol = HDCP_PROTOCOL_DP,
 };
 
 static void intel_edp_panel_vdd_sanitize(struct intel_dp *intel_dp)
-- 
2.7.4

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  parent reply	other threads:[~2019-02-09  7:12 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-09  7:12 [PATCH v12 00/38] drm/i915: Implement HDCP2.2 Ramalingam C
2019-02-09  7:12 ` [PATCH v12 01/38] drm/doc: document recommended component helper usage Ramalingam C
2019-02-11  8:31   ` Daniel Vetter
2019-02-12 12:44   ` Laurent Pinchart
2019-02-12 12:52     ` Daniel Vetter
2019-02-09  7:12 ` [PATCH v12 02/38] drm/i915: Gathering the HDCP1.4 routines together Ramalingam C
2019-02-09  7:12 ` [PATCH v12 03/38] drm: header for i915 - MEI_HDCP interface Ramalingam C
2019-02-09  7:12 ` [PATCH v12 04/38] drm/i915: Initialize HDCP2.2 Ramalingam C
2019-02-09  7:12 ` [PATCH v12 05/38] drm/i915: MEI interface definition Ramalingam C
2019-02-09  7:12 ` [PATCH v12 06/38] drm/i915: hdcp1.4 CP_IRQ handling and SW encryption tracking Ramalingam C
2019-02-09  7:12 ` [PATCH v12 07/38] drm/i915: Enable and Disable of HDCP2.2 Ramalingam C
2019-02-09  7:12 ` [PATCH v12 08/38] drm/i915: Implement HDCP2.2 receiver authentication Ramalingam C
2019-02-09  7:12 ` [PATCH v12 09/38] drm: helper functions for hdcp2 seq_num to from u32 Ramalingam C
2019-02-09  7:12 ` [PATCH v12 10/38] drm/i915: Implement HDCP2.2 repeater authentication Ramalingam C
2019-02-09  7:12 ` [PATCH v12 11/38] drm: HDCP2.2 link check period Ramalingam C
2019-02-09  7:12 ` [PATCH v12 12/38] drm/i915: Implement HDCP2.2 link integrity check Ramalingam C
2019-02-09  7:12 ` [PATCH v12 13/38] drm/i915: Handle HDCP2.2 downstream topology change Ramalingam C
2019-02-09  7:12 ` [PATCH v12 14/38] drm: removing the DP Errata msg and its msg id Ramalingam C
2019-02-09  7:12 ` Ramalingam C [this message]
2019-02-09  7:12 ` [PATCH v12 16/38] drm/i915: Implement the HDCP2.2 support for HDMI Ramalingam C
2019-02-09  7:12 ` [PATCH v12 17/38] drm/i915: CP_IRQ handling for DP HDCP2.2 msgs Ramalingam C
2019-02-09  7:12 ` [PATCH v12 18/38] drm/i915: Fix KBL HDCP2.2 encrypt status signalling Ramalingam C
2019-02-09  7:12 ` [PATCH v12 19/38] mei: bus: whitelist hdcp client Ramalingam C
2019-02-09  7:12 ` [PATCH v12 20/38] mei: bus: export to_mei_cl_device for mei client device drivers Ramalingam C
2019-02-09  7:12 ` [PATCH v12 21/38] mei: me: add ice lake point device id Ramalingam C
2019-02-09  7:57   ` Greg KH
2019-02-09  8:23     ` Winkler, Tomas
2019-02-12 13:28   ` Sasha Levin
2019-02-12 13:28   ` Sasha Levin via dri-devel
2019-02-09  7:12 ` [PATCH v12 22/38] misc/mei/hdcp: Client driver for HDCP application Ramalingam C
2019-02-09  7:12 ` [PATCH v12 23/38] misc/mei/hdcp: Define ME FW interface for HDCP2.2 Ramalingam C
2019-02-09  7:12 ` [PATCH v12 24/38] misc/mei/hdcp: Initiate Wired HDCP2.2 Tx Session Ramalingam C
2019-02-09 16:09   ` Winkler, Tomas
2019-02-10  8:18     ` C, Ramalingam
2019-02-10  8:25       ` Winkler, Tomas
2019-02-10  9:02         ` C, Ramalingam
2019-02-10 19:58           ` Winkler, Tomas
2019-02-11  5:04   ` [PATCH v13 " Ramalingam C
2019-02-09  7:12 ` [PATCH v12 25/38] misc/mei/hdcp: Verify Receiver Cert and prepare km Ramalingam C
2019-02-09  7:12 ` [PATCH v12 26/38] misc/mei/hdcp: Verify H_prime Ramalingam C
2019-02-09  7:12 ` [PATCH v12 27/38] misc/mei/hdcp: Store the HDCP Pairing info Ramalingam C
2019-02-09  7:12 ` [PATCH v12 28/38] misc/mei/hdcp: Initiate Locality check Ramalingam C
2019-02-09  7:12 ` [PATCH v12 29/38] misc/mei/hdcp: Verify L_prime Ramalingam C
2019-02-09  7:12 ` [PATCH v12 30/38] misc/mei/hdcp: Prepare Session Key Ramalingam C
2019-02-09  7:13 ` [PATCH v12 31/38] misc/mei/hdcp: Repeater topology verification and ack Ramalingam C
2019-02-09  7:13 ` [PATCH v12 32/38] misc/mei/hdcp: Verify M_prime Ramalingam C
2019-02-11 18:10   ` Winkler, Tomas
2019-02-09  7:13 ` [PATCH v12 33/38] misc/mei/hdcp: Enabling the HDCP authentication Ramalingam C
2019-02-09  7:13 ` [PATCH v12 34/38] misc/mei/hdcp: Closing wired HDCP2.2 Tx Session Ramalingam C
2019-02-09  7:13 ` [PATCH v12 35/38] misc/mei/hdcp: Component framework for I915 Interface Ramalingam C
2019-02-09  7:13 ` [PATCH v12 36/38] FOR_TEST_ONLY: i915/Kconfig: Select mei_hdcp by I915 Ramalingam C
2019-02-09  7:13 ` [PATCH v12 37/38] FOR_TESTING_ONLY: debugfs: Excluding the LSPCon for HDCP1.4 Ramalingam C
2019-02-09  7:13 ` [PATCH v12 38/38] FOR_TESTING_ONLY: ICL: Limit clk to <= 340MHz Ramalingam C
2019-02-09  7:36 ` ✗ Fi.CI.CHECKPATCH: warning for drm/i915: Implement HDCP2.2 Patchwork
2019-02-09  7:46 ` ✗ Fi.CI.SPARSE: " Patchwork
2019-02-09  8:04 ` ✓ Fi.CI.BAT: success " Patchwork
2019-02-09 10:14 ` ✓ Fi.CI.IGT: " Patchwork
2019-02-11  5:36 ` ✗ Fi.CI.CHECKPATCH: warning for drm/i915: Implement HDCP2.2 (rev2) Patchwork
2019-02-11  5:46 ` ✗ Fi.CI.SPARSE: " Patchwork
2019-02-11  5:58 ` ✓ Fi.CI.BAT: success " Patchwork
2019-02-11  8:06 ` ✗ Fi.CI.IGT: failure " Patchwork

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1549696387-28268-16-git-send-email-ramalingam.c@intel.com \
    --to=ramalingam.c@intel.com \
    --cc=daniel.vetter@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=tomas.winkler@intel.com \
    --cc=uma.shankar@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.