[PATCH v1 00/15] Big fixes, retries, handle a race condition

[PATCH v1 00/15] Big fixes, retries, handle a race condition

[Yaniv Gardi]

This serie of 15 small patches should be pushed after the series of 8 patches
I have uploaded to the upstream a week ago:
"Fix error message and present UFS variant probe"

Yaniv Gardi (15):
  scsi: ufs: clear UTRD, UPIU req and rsp before new transfers
  scsi: ufs: clear fields UTRD, UPIU req and rsp before new transfers
  scsi: ufs: verify command tag validity
  scsi: ufs: clear outstanding_request bit in case query timeout
  scsi: ufs: increase fDeviceInit query response timeout
  scsi: ufs: avoid exception event handler racing with PM callbacks
  scsi: ufs: set REQUEST_SENSE command size to 18 bytes
  scsi: ufs: add retries to dme_peer get and set attribute
  scsi: ufs: add retries for hibern8 enter
  scsi: ufs: fix error recovery after the hibern8 exit failure
  scsi: ufs: retry failed query flag requests
  scsi: ufs: reduce the interrupts for power mode change requests
  scsi: ufs: add missing memory barriers
  scsi: ufs: commit descriptors before setting the doorbell
  scsi: ufs: add wrapper for retrying sending query attribute

 drivers/scsi/ufs/ufshcd.c | 411 ++++++++++++++++++++++++++++++++++++----------
 drivers/scsi/ufs/ufshcd.h |   4 +
 2 files changed, 331 insertions(+), 84 deletions(-)

-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 01/15] scsi: ufs: clear UTRD, UPIU req and rsp before new transfers

[Yaniv Gardi]

Clear the UFS data structures before sending new request.

The SCSI command is sent to the device within the UFS UPIU request.
As part of the transfer UPIU preparation, the SCSI command is copied
to the UPIU structure according to the SCSI command size.
As different SCSI commands differ in size from each other, we need
to clear the whole SCSI command field to prevent sending uninitialized
data to the device.

The UPIU response doesn't always include the sense data and can differ
in size.
Hence, the UPIU response should also be cleared before the transfer.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 131c720..3428f72 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3,7 +3,7 @@
  *
  * This code is based on drivers/scsi/ufs/ufshcd.c
  * Copyright (C) 2011-2013 Samsung India Software Operations
- * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
  *
  * Authors:
  *	Santosh Yaraganavi <santosh.sy@samsung.com>
@@ -1035,6 +1035,7 @@ static int ufshcd_map_sg(struct ufshcd_lrb *lrbp)
 				cpu_to_le32(lower_32_bits(sg->dma_address));
 			prd_table[i].upper_addr =
 				cpu_to_le32(upper_32_bits(sg->dma_address));
+			prd_table[i].reserved = 0;
 		}
 	} else {
 		lrbp->utr_descriptor_ptr->prd_table_length = 0;
@@ -1117,7 +1118,8 @@ static void ufshcd_prepare_req_desc_hdr(struct ufshcd_lrb *lrbp,
 
 	/* Transfer request descriptor header fields */
 	req_desc->header.dword_0 = cpu_to_le32(dword_0);
-
+	/* dword_1 is reserved, hence it is set to 0 */
+	req_desc->header.dword_1 = 0;
 	/*
 	 * assigning invalid value for command status. Controller
 	 * updates OCS on command completion, with the command
@@ -1125,6 +1127,8 @@ static void ufshcd_prepare_req_desc_hdr(struct ufshcd_lrb *lrbp,
 	 */
 	req_desc->header.dword_2 =
 		cpu_to_le32(OCS_INVALID_COMMAND_STATUS);
+	/* dword_3 is reserved, hence it is set to 0 */
+	req_desc->header.dword_3 = 0;
 }
 
 /**
@@ -1137,6 +1141,7 @@ static
 void ufshcd_prepare_utp_scsi_cmd_upiu(struct ufshcd_lrb *lrbp, u32 upiu_flags)
 {
 	struct utp_upiu_req *ucd_req_ptr = lrbp->ucd_req_ptr;
+	unsigned short cdb_len;
 
 	/* command descriptor fields */
 	ucd_req_ptr->header.dword_0 = UPIU_HEADER_DWORD(
@@ -1151,8 +1156,12 @@ void ufshcd_prepare_utp_scsi_cmd_upiu(struct ufshcd_lrb *lrbp, u32 upiu_flags)
 	ucd_req_ptr->sc.exp_data_transfer_len =
 		cpu_to_be32(lrbp->cmd->sdb.length);
 
-	memcpy(ucd_req_ptr->sc.cdb, lrbp->cmd->cmnd,
-		(min_t(unsigned short, lrbp->cmd->cmd_len, MAX_CDB_SIZE)));
+	cdb_len = min_t(unsigned short, lrbp->cmd->cmd_len, MAX_CDB_SIZE);
+	memcpy(ucd_req_ptr->sc.cdb, lrbp->cmd->cmnd, cdb_len);
+	if (cdb_len < MAX_CDB_SIZE)
+		memset(ucd_req_ptr->sc.cdb + cdb_len, 0,
+		       (MAX_CDB_SIZE - cdb_len));
+	memset(lrbp->ucd_rsp_ptr, 0, sizeof(struct utp_upiu_rsp));
 }
 
 /**
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 02/15] scsi: ufs: clear fields UTRD, UPIU req and rsp before new transfers

[Yaniv Gardi]

Some of the data structures (like response UPIU) and/or its elements
(unused fields) should be cleared before sending out the respective
command to UFS device.

This change clears the UPIU response data structure for query commands
and NOP command before sending out the command. We also initialize the
PRDT table length to zero which should take care of commands which doesn't
have any data associated with it. We are also clearing the unused fields in
request UPIU for NOP command.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 3428f72..2d3ebca 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1129,6 +1129,8 @@ static void ufshcd_prepare_req_desc_hdr(struct ufshcd_lrb *lrbp,
 		cpu_to_le32(OCS_INVALID_COMMAND_STATUS);
 	/* dword_3 is reserved, hence it is set to 0 */
 	req_desc->header.dword_3 = 0;
+
+	req_desc->prd_table_length = 0;
 }
 
 /**
@@ -1198,6 +1200,7 @@ static void ufshcd_prepare_utp_query_req_upiu(struct ufs_hba *hba,
 	if (query->request.upiu_req.opcode == UPIU_QUERY_OPCODE_WRITE_DESC)
 		memcpy(descp, query->descriptor, len);
 
+	memset(lrbp->ucd_rsp_ptr, 0, sizeof(struct utp_upiu_rsp));
 }
 
 static inline void ufshcd_prepare_utp_nop_upiu(struct ufshcd_lrb *lrbp)
@@ -1210,6 +1213,11 @@ static inline void ufshcd_prepare_utp_nop_upiu(struct ufshcd_lrb *lrbp)
 	ucd_req_ptr->header.dword_0 =
 		UPIU_HEADER_DWORD(
 			UPIU_TRANSACTION_NOP_OUT, 0, 0, lrbp->task_tag);
+	/* clear rest of the fields of basic header */
+	ucd_req_ptr->header.dword_1 = 0;
+	ucd_req_ptr->header.dword_2 = 0;
+
+	memset(lrbp->ucd_rsp_ptr, 0, sizeof(struct utp_upiu_rsp));
 }
 
 /**
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 03/15] scsi: ufs: verify command tag validity

[Yaniv Gardi]

A race condition appear to exist between request completion when
scsi_done() is called to end the request and set the tag back to
-1 (at blk_queue_end_tag() scsi_end_request), and scsi layer error
handling which aborts the command and reuses it to request sense
data. Sending the request sense is done with tag which was set to -1
and so it is invalid.
Assert command tag passed from scsi layer is valid.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 2d3ebca..61e98a9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -190,6 +190,10 @@ static int ufshcd_config_pwr_mode(struct ufs_hba *hba,
 		struct ufs_pa_layer_attr *desired_pwr_mode);
 static int ufshcd_change_power_mode(struct ufs_hba *hba,
 			     struct ufs_pa_layer_attr *pwr_mode);
+static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
+{
+	return tag >= 0 && tag < hba->nutrs;
+}
 
 static inline int ufshcd_enable_irq(struct ufs_hba *hba)
 {
@@ -1310,6 +1314,12 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 	hba = shost_priv(host);
 
 	tag = cmd->request->tag;
+	if (!ufshcd_valid_tag(hba, tag)) {
+		dev_err(hba->dev,
+			"%s: invalid command tag %d: cmd=0x%p, cmd->request=0x%p",
+			__func__, tag, cmd, cmd->request);
+		BUG();
+	}
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	switch (hba->ufshcd_state) {
@@ -3862,11 +3872,21 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 	host = cmd->device->host;
 	hba = shost_priv(host);
 	tag = cmd->request->tag;
+	if (!ufshcd_valid_tag(hba, tag)) {
+		dev_err(hba->dev,
+			"%s: invalid command tag %d: cmd=0x%p, cmd->request=0x%p",
+			__func__, tag, cmd, cmd->request);
+		BUG();
+	}
 
 	ufshcd_hold(hba, false);
 	/* If command is already aborted/completed, return SUCCESS */
-	if (!(test_bit(tag, &hba->outstanding_reqs)))
+	if (!(test_bit(tag, &hba->outstanding_reqs))) {
+		dev_err(hba->dev,
+			"%s: cmd at tag %d already completed, outstanding=0x%lx, doorbell=0x%x\n",
+			__func__, tag, hba->outstanding_reqs, reg);
 		goto out;
+	}
 
 	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	if (!(reg & (1 << tag))) {
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 04/15] scsi: ufs: clear outstanding_request bit in case query timeout

[Yaniv Gardi]

When sending a query to the device returns with a timeout error,
we clear the corresponding bit in the DOORBELL register but
we don't clear the outstanding_request field as we should.
This patch fixes this bug.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 61e98a9..c346a300 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -364,6 +364,16 @@ static inline void ufshcd_utrl_clear(struct ufs_hba *hba, u32 pos)
 }
 
 /**
+ * ufshcd_outstanding_req_clear - Clear a bit in outstanding request field
+ * @hba: per adapter instance
+ * @tag: position of the bit to be cleared
+ */
+static inline void ufshcd_outstanding_req_clear(struct ufs_hba *hba, int tag)
+{
+	__clear_bit(tag, &hba->outstanding_reqs);
+}
+
+/**
  * ufshcd_get_lists_status - Check UCRDY, UTRLRDY and UTMRLRDY
  * @reg: Register value of host controller status
  *
@@ -1502,9 +1512,17 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
 
 	if (!time_left) {
 		err = -ETIMEDOUT;
+		dev_dbg(hba->dev, "%s: dev_cmd request timedout, tag %d\n",
+			__func__, lrbp->task_tag);
 		if (!ufshcd_clear_cmd(hba, lrbp->task_tag))
-			/* sucessfully cleared the command, retry if needed */
+			/* successfully cleared the command, retry if needed */
 			err = -EAGAIN;
+		/*
+		 * in case of an error, after clearing the doorbell,
+		 * we also need to clear the outstanding_request
+		 * field in hba
+		 */
+		ufshcd_outstanding_req_clear(hba, lrbp->task_tag);
 	}
 
 	return err;
@@ -3942,7 +3960,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 	scsi_dma_unmap(cmd);
 
 	spin_lock_irqsave(host->host_lock, flags);
-	__clear_bit(tag, &hba->outstanding_reqs);
+	ufshcd_outstanding_req_clear(hba, tag);
 	hba->lrb[tag].cmd = NULL;
 	spin_unlock_irqrestore(host->host_lock, flags);
 
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 05/15] scsi: ufs: increase fDeviceInit query response timeout

[Yaniv Gardi]

fDeviceInit query response time for some devices is too long that default
query request timeout of 100ms may not be enough. Experiments show that
fDeviceInit response sometimes takes 500ms so to be on safer side this
change sets the timeout to 600ms. Without this change, we might
unnecessarily have to retry fDeviceInit query requests multiple times and
each query request timeout prints one error message.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index c346a300..ab48220 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -58,6 +58,12 @@
 #define QUERY_REQ_RETRIES 10
 /* Query request timeout */
 #define QUERY_REQ_TIMEOUT 30 /* msec */
+/*
+ * Query request timeout for fDeviceInit flag
+ * fDeviceInit query response time for some devices is too large that default
+ * QUERY_REQ_TIMEOUT may not be enough for such devices.
+ */
+#define QUERY_FDEVICEINIT_REQ_TIMEOUT 600 /* msec */
 
 /* Task management command timeout */
 #define TM_CMD_TIMEOUT	100 /* msecs */
@@ -1651,6 +1657,7 @@ static int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
 	struct ufs_query_req *request = NULL;
 	struct ufs_query_res *response = NULL;
 	int err, index = 0, selector = 0;
+	int timeout = QUERY_REQ_TIMEOUT;
 
 	BUG_ON(!hba);
 
@@ -1683,7 +1690,10 @@ static int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
 		goto out_unlock;
 	}
 
-	err = ufshcd_exec_dev_cmd(hba, DEV_CMD_TYPE_QUERY, QUERY_REQ_TIMEOUT);
+	if (idn == QUERY_FLAG_IDN_FDEVICEINIT)
+		timeout = QUERY_FDEVICEINIT_REQ_TIMEOUT;
+
+	err = ufshcd_exec_dev_cmd(hba, DEV_CMD_TYPE_QUERY, timeout);
 
 	if (err) {
 		dev_err(hba->dev,
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 06/15] scsi: ufs: avoid exception event handler racing with PM callbacks

[Yaniv Gardi]

If device raises the exception event in the response to the commands
sent during the runtime/system PM callbacks, exception event handler
might run in parallel with PM callbacks and may see unclocked register
accesses. This change fixes this issue by not scheduling the exception
event handler while PM callbacks are running.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index ab48220..f248df2 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3145,7 +3145,20 @@ ufshcd_transfer_rsp_status(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 			scsi_status = result & MASK_SCSI_STATUS;
 			result = ufshcd_scsi_cmd_status(lrbp, scsi_status);
 
-			if (ufshcd_is_exception_event(lrbp->ucd_rsp_ptr))
+			/*
+			 * Currently we are only supporting BKOPs exception
+			 * events hence we can ignore BKOPs exception event
+			 * during power management callbacks. BKOPs exception
+			 * event is not expected to be raised in runtime suspend
+			 * callback as it allows the urgent bkops.
+			 * During system suspend, we are anyway forcefully
+			 * disabling the bkops and if urgent bkops is needed
+			 * it will be enabled on system resume. Long term
+			 * solution could be to abort the system suspend if
+			 * UFS device needs urgent BKOPs.
+			 */
+			if (!hba->pm_op_in_progress &&
+			    ufshcd_is_exception_event(lrbp->ucd_rsp_ptr))
 				schedule_work(&hba->eeh_work);
 			break;
 		case UPIU_TRANSACTION_REJECT_UPIU:
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 07/15] scsi: ufs: set REQUEST_SENSE command size to 18 bytes

[Yaniv Gardi]

According to UFS device specification REQUEST_SENSE command can
only report back up to 18 bytes of data.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index f248df2..d0269ad 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -42,6 +42,7 @@
 
 #include "ufshcd.h"
 #include "unipro.h"
+#define UFSHCD_REQ_SENSE_SIZE	18
 
 #define UFSHCD_ENABLE_INTRS	(UTP_TRANSFER_REQ_COMPL |\
 				 UTP_TASK_REQ_COMPL |\
@@ -836,7 +837,7 @@ static inline void ufshcd_copy_sense_data(struct ufshcd_lrb *lrbp)
 		len = be16_to_cpu(lrbp->ucd_rsp_ptr->sr.sense_data_len);
 		memcpy(lrbp->sense_buffer,
 			lrbp->ucd_rsp_ptr->sr.sense_data,
-			min_t(int, len, SCSI_SENSE_BUFFERSIZE));
+			min_t(int, len, UFSHCD_REQ_SENSE_SIZE));
 	}
 }
 
@@ -1381,7 +1382,7 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 
 	WARN_ON(lrbp->cmd);
 	lrbp->cmd = cmd;
-	lrbp->sense_bufflen = SCSI_SENSE_BUFFERSIZE;
+	lrbp->sense_bufflen = UFSHCD_REQ_SENSE_SIZE;
 	lrbp->sense_buffer = cmd->sense_buffer;
 	lrbp->task_tag = tag;
 	lrbp->lun = ufshcd_scsi_to_upiu_lun(cmd->device->lun);
@@ -4817,19 +4818,19 @@ ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp)
 				0,
 				0,
 				0,
-				SCSI_SENSE_BUFFERSIZE,
+				UFSHCD_REQ_SENSE_SIZE,
 				0};
 	char *buffer;
 	int ret;
 
-	buffer = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
+	buffer = kzalloc(UFSHCD_REQ_SENSE_SIZE, GFP_KERNEL);
 	if (!buffer) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
 	ret = scsi_execute_req_flags(sdp, cmd, DMA_FROM_DEVICE, buffer,
-				SCSI_SENSE_BUFFERSIZE, NULL,
+				UFSHCD_REQ_SENSE_SIZE, NULL,
 				msecs_to_jiffies(1000), 3, NULL, REQ_PM);
 	if (ret)
 		pr_err("%s: failed with err %d\n", __func__, ret);
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 08/15] scsi: ufs: add retries to dme_peer get and set attribute

[Yaniv Gardi]

The dme_peer get/set attribute commands are prone to errors, therefore
we add three retries for the UIC command sending.
Error code returned from ufshcd_send_uic_cmd() is checked, and unless
it was successful or the retries have finished, another command will be
sent.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index d0269ad..a146587 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -69,6 +69,9 @@
 /* Task management command timeout */
 #define TM_CMD_TIMEOUT	100 /* msecs */
 
+/* maximum number of retries for a general UIC command  */
+#define UFS_UIC_COMMAND_RETRIES 3
+
 /* maximum number of link-startup retries */
 #define DME_LINKSTARTUP_RETRIES 3
 
@@ -2184,6 +2187,7 @@ int ufshcd_dme_set_attr(struct ufs_hba *hba, u32 attr_sel,
 	};
 	const char *set = action[!!peer];
 	int ret;
+	int retries = UFS_UIC_COMMAND_RETRIES;
 
 	uic_cmd.command = peer ?
 		UIC_CMD_DME_PEER_SET : UIC_CMD_DME_SET;
@@ -2191,10 +2195,18 @@ int ufshcd_dme_set_attr(struct ufs_hba *hba, u32 attr_sel,
 	uic_cmd.argument2 = UIC_ARG_ATTR_TYPE(attr_set);
 	uic_cmd.argument3 = mib_val;
 
-	ret = ufshcd_send_uic_cmd(hba, &uic_cmd);
-	if (ret)
-		dev_err(hba->dev, "%s: attr-id 0x%x val 0x%x error code %d\n",
-			set, UIC_GET_ATTR_ID(attr_sel), mib_val, ret);
+	do {
+		/* for peer attributes we retry upon failure */
+		ret = ufshcd_send_uic_cmd(hba, &uic_cmd);
+		if (ret)
+			dev_dbg(hba->dev, "%s: attr-id 0x%x val 0x%x error code %d\n",
+				set, UIC_GET_ATTR_ID(attr_sel), mib_val, ret);
+	} while (ret && peer && --retries);
+
+	if (!retries)
+		dev_err(hba->dev, "%s: attr-id 0x%x val 0x%x failed %d retries\n",
+				set, UIC_GET_ATTR_ID(attr_sel), mib_val,
+				retries);
 
 	return ret;
 }
@@ -2219,6 +2231,7 @@ int ufshcd_dme_get_attr(struct ufs_hba *hba, u32 attr_sel,
 	};
 	const char *get = action[!!peer];
 	int ret;
+	int retries = UFS_UIC_COMMAND_RETRIES;
 	struct ufs_pa_layer_attr orig_pwr_info;
 	struct ufs_pa_layer_attr temp_pwr_info;
 	bool pwr_mode_change = false;
@@ -2249,14 +2262,19 @@ int ufshcd_dme_get_attr(struct ufs_hba *hba, u32 attr_sel,
 		UIC_CMD_DME_PEER_GET : UIC_CMD_DME_GET;
 	uic_cmd.argument1 = attr_sel;
 
-	ret = ufshcd_send_uic_cmd(hba, &uic_cmd);
-	if (ret) {
-		dev_err(hba->dev, "%s: attr-id 0x%x error code %d\n",
-			get, UIC_GET_ATTR_ID(attr_sel), ret);
-		goto out;
-	}
+	do {
+		/* for peer attributes we retry upon failure */
+		ret = ufshcd_send_uic_cmd(hba, &uic_cmd);
+		if (ret)
+			dev_dbg(hba->dev, "%s: attr-id 0x%x error code %d\n",
+				get, UIC_GET_ATTR_ID(attr_sel), ret);
+	} while (ret && peer && --retries);
+
+	if (!retries)
+		dev_err(hba->dev, "%s: attr-id 0x%x failed %d retries\n",
+				get, UIC_GET_ATTR_ID(attr_sel), retries);
 
-	if (mib_val)
+	if (mib_val && !ret)
 		*mib_val = uic_cmd.argument3;
 
 	if (peer && (hba->quirks & UFSHCD_QUIRK_DME_PEER_ACCESS_AUTO_MODE)
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 09/15] scsi: ufs: add retries for hibern8 enter

[Yaniv Gardi]

If hibern8 enter command fails then UFS link state may be unknown which
may result into timeout of all the commands issued after failure.

This change does 2 things (for pre-defined number of retry counts) after
hibern8 enter failure:
1. Recovers the UFS link to active state
2. If link is recovered to active state, tries to put the UFS link in
   hibern8 enter again until retry count expires.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a146587..6d47e9e 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -75,6 +75,9 @@
 /* maximum number of link-startup retries */
 #define DME_LINKSTARTUP_RETRIES 3
 
+/* Maximum retries for Hibern8 enter */
+#define UIC_HIBERN8_ENTER_RETRIES 3
+
 /* maximum number of reset retries before giving up */
 #define MAX_HOST_RESET_RETRIES 5
 
@@ -2389,13 +2392,32 @@ out:
 	return ret;
 }
 
-static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
+static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
 {
+	int ret;
 	struct uic_command uic_cmd = {0};
 
 	uic_cmd.command = UIC_CMD_DME_HIBER_ENTER;
+	ret = ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
+
+	if (ret)
+		dev_err(hba->dev, "%s: hibern8 enter failed. ret = %d",
+			__func__, ret);
+
+	return ret;
+}
+
+static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
+{
+	int ret = 0, retries;
 
-	return ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
+	for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0; retries--) {
+		ret = __ufshcd_uic_hibern8_enter(hba);
+		if (!ret || ret == -ENOLINK)
+			goto out;
+	}
+out:
+	return ret;
 }
 
 static int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 10/15] scsi: ufs: fix error recovery after the hibern8 exit failure

[Yaniv Gardi]

Hibern8 exit can be called from 3 different context:
    - ufshcd_hibern8_exit_work
    - ufshcd_ungate_work
    - runtime/system resume

If hibern8 exit fails for some reason then we try to bring the link to
active state by link startup but this recovery mechanism results into
deadlock or errors from first 2 context listed above. This change fixes
the recovery by adding proper error handling mechanism.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 58 +++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 6d47e9e..30aec4d 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -609,6 +609,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	hba->clk_gating.active_reqs++;
 
+	if (ufshcd_eh_in_progress(hba)) {
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		return 0;
+	}
+
 start:
 	switch (hba->clk_gating.state) {
 	case CLKS_ON:
@@ -724,7 +729,8 @@ static void __ufshcd_release(struct ufs_hba *hba)
 	if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended
 		|| hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL
 		|| hba->lrb_in_use || hba->outstanding_tasks
-		|| hba->active_uic_cmd || hba->uic_async_done)
+		|| hba->active_uic_cmd || hba->uic_async_done
+		|| ufshcd_eh_in_progress(hba))
 		return;
 
 	hba->clk_gating.state = REQ_CLKS_OFF;
@@ -1362,6 +1368,13 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 		cmd->scsi_done(cmd);
 		goto out_unlock;
 	}
+
+	/* if error handling is in progress, don't issue commands */
+	if (ufshcd_eh_in_progress(hba)) {
+		set_host_byte(cmd, DID_ERROR);
+		cmd->scsi_done(cmd);
+		goto out_unlock;
+	}
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
 	/* acquire the tag to make sure device cmds don't use it */
@@ -2392,6 +2405,31 @@ out:
 	return ret;
 }
 
+static int ufshcd_link_recovery(struct ufs_hba *hba)
+{
+	int ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	hba->ufshcd_state = UFSHCD_STATE_RESET;
+	ufshcd_set_eh_in_progress(hba);
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+	ret = ufshcd_host_reset_and_restore(hba);
+
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	if (ret)
+		hba->ufshcd_state = UFSHCD_STATE_ERROR;
+	ufshcd_clear_eh_in_progress(hba);
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+	if (ret)
+		dev_err(hba->dev, "%s: link recovery failed, err %d",
+			__func__, ret);
+
+	return ret;
+}
+
 static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
 {
 	int ret;
@@ -2400,10 +2438,18 @@ static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
 	uic_cmd.command = UIC_CMD_DME_HIBER_ENTER;
 	ret = ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
 
-	if (ret)
+	if (ret) {
 		dev_err(hba->dev, "%s: hibern8 enter failed. ret = %d",
 			__func__, ret);
 
+		/*
+		 * If link recovery fails then return error so that caller
+		 * don't retry the hibern8 enter again.
+		 */
+		if (ufshcd_link_recovery(hba))
+			ret = -ENOLINK;
+	}
+
 	return ret;
 }
 
@@ -2428,8 +2474,9 @@ static int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)
 	uic_cmd.command = UIC_CMD_DME_HIBER_EXIT;
 	ret = ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
 	if (ret) {
-		ufshcd_set_link_off(hba);
-		ret = ufshcd_host_reset_and_restore(hba);
+		dev_err(hba->dev, "%s: hibern8 exit failed. ret = %d",
+			__func__, ret);
+		ret = ufshcd_link_recovery(hba);
 	}
 
 	return ret;
@@ -4381,7 +4428,6 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
 	/* UFS device is also active now */
 	ufshcd_set_ufs_dev_active(hba);
 	ufshcd_force_reset_auto_bkops(hba);
-	hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
 	hba->wlun_dev_clr_ua = true;
 
 	if (ufshcd_get_max_pwr_mode(hba)) {
@@ -4395,6 +4441,8 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
 					__func__, ret);
 	}
 
+	/* set the state as operational after switching to desired gear */
+	hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
 	/*
 	 * If we are in error handling context or in power management callbacks
 	 * context, no need to scan the host
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 11/15] scsi: ufs: retry failed query flag requests

[Yaniv Gardi]

UFS flag query requests may fail sometimes due to timeouts etc.
Add a wrapper function to retry up to 10 times in case of such
failure, similar to retries being made for attribute queries.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 63 ++++++++++++++++++++++++++++-------------------
 drivers/scsi/ufs/ufshcd.h |  4 +++
 2 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 30aec4d..0a8aa88 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1662,6 +1662,29 @@ static inline void ufshcd_init_query(struct ufs_hba *hba,
 	(*request)->upiu_req.selector = selector;
 }
 
+static int ufshcd_query_flag_retry(struct ufs_hba *hba,
+	enum query_opcode opcode, enum flag_idn idn, bool *flag_res)
+{
+	int ret;
+	int retries;
+
+	for (retries = 0; retries < QUERY_REQ_RETRIES; retries++) {
+		ret = ufshcd_query_flag(hba, opcode, idn, flag_res);
+		if (ret)
+			dev_dbg(hba->dev,
+				"%s: failed with error %d, retries %d\n",
+				__func__, ret, retries);
+		else
+			break;
+	}
+
+	if (ret)
+		dev_err(hba->dev,
+			"%s: query attribute, opcode %d, idn %d, failed with error %d after %d retires\n",
+			__func__, opcode, idn, ret, retries);
+	return ret;
+}
+
 /**
  * ufshcd_query_flag() - API function for sending flag query requests
  * hba: per-adapter instance
@@ -1671,7 +1694,7 @@ static inline void ufshcd_init_query(struct ufs_hba *hba,
  *
  * Returns 0 for success, non-zero in case of failure
  */
-static int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
+int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
 			enum flag_idn idn, bool *flag_res)
 {
 	struct ufs_query_req *request = NULL;
@@ -2656,17 +2679,12 @@ static int ufshcd_config_pwr_mode(struct ufs_hba *hba,
  */
 static int ufshcd_complete_dev_init(struct ufs_hba *hba)
 {
-	int i, retries, err = 0;
+	int i;
+	int err;
 	bool flag_res = 1;
 
-	for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
-		/* Set the fDeviceInit flag */
-		err = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_SET_FLAG,
-					QUERY_FLAG_IDN_FDEVICEINIT, NULL);
-		if (!err || err == -ETIMEDOUT)
-			break;
-		dev_dbg(hba->dev, "%s: error %d retrying\n", __func__, err);
-	}
+	err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_SET_FLAG,
+		QUERY_FLAG_IDN_FDEVICEINIT, NULL);
 	if (err) {
 		dev_err(hba->dev,
 			"%s setting fDeviceInit flag failed with error %d\n",
@@ -2674,18 +2692,11 @@ static int ufshcd_complete_dev_init(struct ufs_hba *hba)
 		goto out;
 	}
 
-	/* poll for max. 100 iterations for fDeviceInit flag to clear */
-	for (i = 0; i < 100 && !err && flag_res; i++) {
-		for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
-			err = ufshcd_query_flag(hba,
-					UPIU_QUERY_OPCODE_READ_FLAG,
-					QUERY_FLAG_IDN_FDEVICEINIT, &flag_res);
-			if (!err || err == -ETIMEDOUT)
-				break;
-			dev_dbg(hba->dev, "%s: error %d retrying\n", __func__,
-					err);
-		}
-	}
+	/* poll for max. 1000 iterations for fDeviceInit flag to clear */
+	for (i = 0; i < 1000 && !err && flag_res; i++)
+		err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_READ_FLAG,
+			QUERY_FLAG_IDN_FDEVICEINIT, &flag_res);
+
 	if (err)
 		dev_err(hba->dev,
 			"%s reading fDeviceInit flag failed with error %d\n",
@@ -3432,7 +3443,7 @@ static int ufshcd_enable_auto_bkops(struct ufs_hba *hba)
 	if (hba->auto_bkops_enabled)
 		goto out;
 
-	err = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_SET_FLAG,
+	err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_SET_FLAG,
 			QUERY_FLAG_IDN_BKOPS_EN, NULL);
 	if (err) {
 		dev_err(hba->dev, "%s: failed to enable bkops %d\n",
@@ -3481,7 +3492,7 @@ static int ufshcd_disable_auto_bkops(struct ufs_hba *hba)
 		goto out;
 	}
 
-	err = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_CLEAR_FLAG,
+	err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_CLEAR_FLAG,
 			QUERY_FLAG_IDN_BKOPS_EN, NULL);
 	if (err) {
 		dev_err(hba->dev, "%s: failed to disable bkops %d\n",
@@ -4452,8 +4463,8 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
 
 		/* clear any previous UFS device information */
 		memset(&hba->dev_info, 0, sizeof(hba->dev_info));
-		if (!ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_READ_FLAG,
-				       QUERY_FLAG_IDN_PWR_ON_WPE, &flag))
+		if (!ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_READ_FLAG,
+				QUERY_FLAG_IDN_PWR_ON_WPE, &flag))
 			hba->dev_info.f_power_on_wp_en = flag;
 
 		if (!hba->is_init_prefetch)
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 4bb2697..2e8f64b 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -3,6 +3,7 @@
  *
  * This code is based on drivers/scsi/ufs/ufshcd.h
  * Copyright (C) 2011-2013 Samsung India Software Operations
+ * Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
  *
  * Authors:
  *	Santosh Yaraganavi <santosh.sy@samsung.com>
@@ -680,6 +681,9 @@ static inline int ufshcd_dme_peer_get(struct ufs_hba *hba,
 	return ufshcd_dme_get_attr(hba, attr_sel, mib_val, DME_PEER);
 }
 
+/* Expose Query-Request API */
+int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
+	enum flag_idn idn, bool *flag_res);
 int ufshcd_hold(struct ufs_hba *hba, bool async);
 void ufshcd_release(struct ufs_hba *hba);
 
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 12/15] scsi: ufs: reduce the interrupts for power mode change requests

[Yaniv Gardi]

DME commands such as Hibern8 enter/exit and gear switch generate 2
completion interrupts, one for confirmation that command is received
by local UniPro and 2nd one is the final confirmation after communication
with remote UniPro. Currently both of these completions are registered
as interrupt events which is not quite necessary and instead we can
just wait for the interrupt of 2nd completion, this should reduce
the number of interrupts and could reduce the unnecessary CPU wakeups
to handle extra interrupts.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 0a8aa88..8f17cf5 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -986,13 +986,15 @@ ufshcd_wait_for_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
  * __ufshcd_send_uic_cmd - Send UIC commands and retrieve the result
  * @hba: per adapter instance
  * @uic_cmd: UIC command
+ * @completion: initialize the completion only if this is set to true
  *
  * Identical to ufshcd_send_uic_cmd() expect mutex. Must be called
  * with mutex held and host_lock locked.
  * Returns 0 only if success.
  */
 static int
-__ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
+__ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd,
+		      bool completion)
 {
 	if (!ufshcd_ready_for_uic_cmd(hba)) {
 		dev_err(hba->dev,
@@ -1000,7 +1002,8 @@ __ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
 		return -EIO;
 	}
 
-	init_completion(&uic_cmd->done);
+	if (completion)
+		init_completion(&uic_cmd->done);
 
 	ufshcd_dispatch_uic_cmd(hba, uic_cmd);
 
@@ -1025,7 +1028,7 @@ ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
 	ufshcd_add_delay_before_dme_cmd(hba);
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	ret = __ufshcd_send_uic_cmd(hba, uic_cmd);
+	ret = __ufshcd_send_uic_cmd(hba, uic_cmd, true);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	if (!ret)
 		ret = ufshcd_wait_for_uic_cmd(hba, uic_cmd);
@@ -2346,6 +2349,7 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 	unsigned long flags;
 	u8 status;
 	int ret;
+	bool reenable_intr = false;
 
 	mutex_lock(&hba->uic_cmd_mutex);
 	init_completion(&uic_async_done);
@@ -2353,15 +2357,17 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	hba->uic_async_done = &uic_async_done;
-	ret = __ufshcd_send_uic_cmd(hba, cmd);
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-	if (ret) {
-		dev_err(hba->dev,
-			"pwr ctrl cmd 0x%x with mode 0x%x uic error %d\n",
-			cmd->command, cmd->argument3, ret);
-		goto out;
+	if (ufshcd_readl(hba, REG_INTERRUPT_ENABLE) & UIC_COMMAND_COMPL) {
+		ufshcd_disable_intr(hba, UIC_COMMAND_COMPL);
+		/*
+		 * Make sure UIC command completion interrupt is disabled before
+		 * issuing UIC command.
+		 */
+		wmb();
+		reenable_intr = true;
 	}
-	ret = ufshcd_wait_for_uic_cmd(hba, cmd);
+	ret = __ufshcd_send_uic_cmd(hba, cmd, false);
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	if (ret) {
 		dev_err(hba->dev,
 			"pwr ctrl cmd 0x%x with mode 0x%x uic error %d\n",
@@ -2387,7 +2393,10 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 	}
 out:
 	spin_lock_irqsave(hba->host->host_lock, flags);
+	hba->active_uic_cmd = NULL;
 	hba->uic_async_done = NULL;
+	if (reenable_intr)
+		ufshcd_enable_intr(hba, UIC_COMMAND_COMPL);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	mutex_unlock(&hba->uic_cmd_mutex);
 
@@ -3812,16 +3821,20 @@ static void ufshcd_sl_intr(struct ufs_hba *hba, u32 intr_status)
  */
 static irqreturn_t ufshcd_intr(int irq, void *__hba)
 {
-	u32 intr_status;
+	u32 intr_status, enabled_intr_status;
 	irqreturn_t retval = IRQ_NONE;
 	struct ufs_hba *hba = __hba;
 
 	spin_lock(hba->host->host_lock);
 	intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
+	enabled_intr_status =
+		intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
 
-	if (intr_status) {
+	if (intr_status)
 		ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
-		ufshcd_sl_intr(hba, intr_status);
+
+	if (enabled_intr_status) {
+		ufshcd_sl_intr(hba, enabled_intr_status);
 		retval = IRQ_HANDLED;
 	}
 	spin_unlock(hba->host->host_lock);
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 13/15] scsi: ufs: add missing memory barriers

[Yaniv Gardi]

Performing several writes to UFS host controller registers has
no gurrantee of ordering, so we must make sure register writes
to setup request list base address etc. are performed before the
run/stop register is enabled.
In addition, when setting up a task request, we must make sure
the updating of descriptors takes places before ringing the
doorbell, similarly to setting up a transfer request.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 8f17cf5..fef0660 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -401,11 +401,9 @@ static inline int ufshcd_get_lists_status(u32 reg)
 	 *  1		UTRLRDY
 	 *  2		UTMRLRDY
 	 *  3		UCRDY
-	 *  4		HEI
-	 *  5		DEI
-	 * 6-7		reserved
+	 * 4-7		reserved
 	 */
-	return (((reg) & (0xFF)) >> 1) ^ (0x07);
+	return ((reg & 0xFF) >> 1) ^ 0x07;
 }
 
 /**
@@ -2726,7 +2724,7 @@ out:
  * To bring UFS host controller to operational state,
  * 1. Enable required interrupts
  * 2. Configure interrupt aggregation
- * 3. Program UTRL and UTMRL base addres
+ * 3. Program UTRL and UTMRL base address
  * 4. Configure run-stop-registers
  *
  * Returns 0 on success, non-zero value on failure
@@ -2756,8 +2754,13 @@ static int ufshcd_make_hba_operational(struct ufs_hba *hba)
 			REG_UTP_TASK_REQ_LIST_BASE_H);
 
 	/*
+	 * Make sure base address and interrupt setup are updated before
+	 * enabling the run/stop registers below.
+	 */
+	wmb();
+
+	/*
 	 * UCRDY, UTMRLDY and UTRLRDY bits must be 1
-	 * DEI, HEI bits must be 0
 	 */
 	reg = ufshcd_readl(hba, REG_CONTROLLER_STATUS);
 	if (!(ufshcd_get_lists_status(reg))) {
@@ -3920,7 +3923,13 @@ static int ufshcd_issue_tm_cmd(struct ufs_hba *hba, int lun_id, int task_id,
 
 	/* send command to the controller */
 	__set_bit(free_slot, &hba->outstanding_tasks);
+
+	/* Make sure descriptors are ready before ringing the task doorbell */
+	wmb();
+
 	ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL);
+	/* Make sure that doorbell is committed immediately */
+	wmb();
 
 	spin_unlock_irqrestore(host->host_lock, flags);
 
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

[PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Yaniv Gardi]

Add a write memory barrier to make sure descriptors prepared are actually
written to memory before ringing the doorbell. We have also added the
write memory barrier after ringing the doorbell register so that
controller sees the new request immediately.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index fef0660..876148b 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
 	ufshcd_clk_scaling_start_busy(hba);
 	__set_bit(task_tag, &hba->outstanding_reqs);
 	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
+	/* Make sure that doorbell is committed immediately */
+	wmb();
 }
 
 /**
@@ -1418,6 +1420,8 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 		goto out;
 	}
 
+	/* Make sure descriptors are ready before ringing the doorbell */
+	wmb();
 	/* issue command to the controller */
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	ufshcd_send_command(hba, tag);
@@ -1627,6 +1631,8 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
 
 	hba->dev_cmd.complete = &wait;
 
+	/* Make sure descriptors are ready before ringing the doorbell */
+	wmb();
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	ufshcd_send_command(hba, tag);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Rob Herring]

On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>
> Add a write memory barrier to make sure descriptors prepared are actually
> written to memory before ringing the doorbell. We have also added the
> write memory barrier after ringing the doorbell register so that
> controller sees the new request immediately.
>
> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>
> ---
>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index fef0660..876148b 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
>         ufshcd_clk_scaling_start_busy(hba);
>         __set_bit(task_tag, &hba->outstanding_reqs);
>         ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
> +       /* Make sure that doorbell is committed immediately */
> +       wmb();

Is this really necessary? Is there a measurable difference?

>  }
>
>  /**
> @@ -1418,6 +1420,8 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
>                 goto out;
>         }
>
> +       /* Make sure descriptors are ready before ringing the doorbell */
> +       wmb();

The writel for the doorbell will do a barrier first. (I didn't check
what exactly ufshcd_writel does, but that is why I don't like these
private access wrappers.)

>         /* issue command to the controller */
>         spin_lock_irqsave(hba->host->host_lock, flags);
>         ufshcd_send_command(hba, tag);
> @@ -1627,6 +1631,8 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
>
>         hba->dev_cmd.complete = &wait;
>
> +       /* Make sure descriptors are ready before ringing the doorbell */
> +       wmb();
>         spin_lock_irqsave(hba->host->host_lock, flags);
>         ufshcd_send_command(hba, tag);
>         spin_unlock_irqrestore(hba->host->host_lock, flags);
> --
> 1.8.5.2
>
> --
> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[ygardi]

> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>
>> Add a write memory barrier to make sure descriptors prepared are
>> actually
>> written to memory before ringing the doorbell. We have also added the
>> write memory barrier after ringing the doorbell register so that
>> controller sees the new request immediately.
>>
>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index fef0660..876148b 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>> unsigned int task_tag)
>>         ufshcd_clk_scaling_start_busy(hba);
>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>         ufshcd_writel(hba, 1 << task_tag,
>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>> +       /* Make sure that doorbell is committed immediately */
>> +       wmb();
>
> Is this really necessary? Is there a measurable difference?

I'm not sure if there is a measurable difference, but as the Door-Bell
register is the one that actually responsible for the HW execution of the
requests, anyhow, it's recommended to its value will be written
instantly to the memory.

Also, as the Interrupt context reads this register, and compare it to the
SW mirroring value (hba->outstanding_reqs) in order to realize what
requests are already completed, it's important to get the correct value
by reading this register, otherwise we might realize a request completion
while it was never even submitted.

>
>>  }
>>
>>  /**
>> @@ -1418,6 +1420,8 @@ static int ufshcd_queuecommand(struct Scsi_Host
>> *host, struct scsi_cmnd *cmd)
>>                 goto out;
>>         }
>>
>> +       /* Make sure descriptors are ready before ringing the doorbell
>> */
>> +       wmb();
>
> The writel for the doorbell will do a barrier first. (I didn't check
> what exactly ufshcd_writel does, but that is why I don't like these
> private access wrappers.)
>
>>         /* issue command to the controller */
>>         spin_lock_irqsave(hba->host->host_lock, flags);
>>         ufshcd_send_command(hba, tag);
>> @@ -1627,6 +1631,8 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba
>> *hba,
>>
>>         hba->dev_cmd.complete = &wait;
>>
>> +       /* Make sure descriptors are ready before ringing the doorbell
>> */
>> +       wmb();
>>         spin_lock_irqsave(hba->host->host_lock, flags);
>>         ufshcd_send_command(hba, tag);
>>         spin_unlock_irqrestore(hba->host->host_lock, flags);
>> --
>> 1.8.5.2
>>
>> --
>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>> member of Code Aurora Forum, hosted by The Linux Foundation
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Rob Herring]

On Tue, Aug 25, 2015 at 7:36 AM,  <ygardi@codeaurora.org> wrote:
>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>
>>> Add a write memory barrier to make sure descriptors prepared are
>>> actually
>>> written to memory before ringing the doorbell. We have also added the
>>> write memory barrier after ringing the doorbell register so that
>>> controller sees the new request immediately.
>>>
>>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>>
>>> ---
>>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>> index fef0660..876148b 100644
>>> --- a/drivers/scsi/ufs/ufshcd.c
>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>>> unsigned int task_tag)
>>>         ufshcd_clk_scaling_start_busy(hba);
>>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>>         ufshcd_writel(hba, 1 << task_tag,
>>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>> +       /* Make sure that doorbell is committed immediately */
>>> +       wmb();
>>
>> Is this really necessary? Is there a measurable difference?
>
> I'm not sure if there is a measurable difference, but as the Door-Bell
> register is the one that actually responsible for the HW execution of the
> requests, anyhow, it's recommended to its value will be written
> instantly to the memory.

A barrier doesn't guarantee speed, only ordering. Unless you can
measure the difference, you should not have it.

> Also, as the Interrupt context reads this register, and compare it to the
> SW mirroring value (hba->outstanding_reqs) in order to realize what
> requests are already completed, it's important to get the correct value
> by reading this register, otherwise we might realize a request completion
> while it was never even submitted.

If a register read can pass a register write out of order, then your
h/w is broken. Plus what if the interrupt occurs before the barrier.

Rob

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[ygardi]

> On Tue, Aug 25, 2015 at 7:36 AM,  <ygardi@codeaurora.org> wrote:
>>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>>
>>>> Add a write memory barrier to make sure descriptors prepared are
>>>> actually
>>>> written to memory before ringing the doorbell. We have also added the
>>>> write memory barrier after ringing the doorbell register so that
>>>> controller sees the new request immediately.
>>>>
>>>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>>>
>>>> ---
>>>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>>>  1 file changed, 6 insertions(+)
>>>>
>>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>>> index fef0660..876148b 100644
>>>> --- a/drivers/scsi/ufs/ufshcd.c
>>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>>>> unsigned int task_tag)
>>>>         ufshcd_clk_scaling_start_busy(hba);
>>>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>>>         ufshcd_writel(hba, 1 << task_tag,
>>>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>>> +       /* Make sure that doorbell is committed immediately */
>>>> +       wmb();
>>>
>>> Is this really necessary? Is there a measurable difference?
>>
>> I'm not sure if there is a measurable difference, but as the Door-Bell
>> register is the one that actually responsible for the HW execution of
>> the
>> requests, anyhow, it's recommended to its value will be written
>> instantly to the memory.
>
> A barrier doesn't guarantee speed, only ordering. Unless you can
> measure the difference, you should not have it.

Rob,
let me have an example:
context#1 updates outstanding_reqs variable and write(DOOR_BELL)
context#2 upon interrupt of a request completion the following happens:
  report completion on each one of the bits in:
  outstanding_reqs ^ read(DOOR_BELL);

0. let's assume the DOOR_BELL = 0x1 (which means 1 active request in slot 0)
1. context#1: update the DOOR_BELL to be 0x3; (2 active requests: in slot
0 and 1)
2. the new value 0x3 is still not written to the DR so DORR_BELL is still
0x1, but outstanding_reqs is already updated = 0x3
3. the request in slot 0 just completed, and interrupt happens, so
DORR_BELL is now 0 (request in slot 0 completed)
4. context#2: outstanding_reqs ^ read(DOOR_BELL) = 0x3 ^ 0x0 = 0x3 =>
wrong conclusion since the request in slot 1 never completed, and actually
never started.


>
>> Also, as the Interrupt context reads this register, and compare it to
>> the
>> SW mirroring value (hba->outstanding_reqs) in order to realize what
>> requests are already completed, it's important to get the correct value
>> by reading this register, otherwise we might realize a request
>> completion
>> while it was never even submitted.
>
> If a register read can pass a register write out of order, then your
> h/w is broken. Plus what if the interrupt occurs before the barrier.
>
> Rob
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Rob Herring]

On Thu, Aug 27, 2015 at 7:11 AM,  <ygardi@codeaurora.org> wrote:
>> On Tue, Aug 25, 2015 at 7:36 AM,  <ygardi@codeaurora.org> wrote:
>>>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>>>
>>>>> Add a write memory barrier to make sure descriptors prepared are
>>>>> actually
>>>>> written to memory before ringing the doorbell. We have also added the
>>>>> write memory barrier after ringing the doorbell register so that
>>>>> controller sees the new request immediately.
>>>>>
>>>>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>>>>
>>>>> ---
>>>>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>>>>  1 file changed, 6 insertions(+)
>>>>>
>>>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>>>> index fef0660..876148b 100644
>>>>> --- a/drivers/scsi/ufs/ufshcd.c
>>>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>>>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>>>>> unsigned int task_tag)
>>>>>         ufshcd_clk_scaling_start_busy(hba);
>>>>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>>>>         ufshcd_writel(hba, 1 << task_tag,
>>>>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>>>> +       /* Make sure that doorbell is committed immediately */
>>>>> +       wmb();
>>>>
>>>> Is this really necessary? Is there a measurable difference?
>>>
>>> I'm not sure if there is a measurable difference, but as the Door-Bell
>>> register is the one that actually responsible for the HW execution of
>>> the
>>> requests, anyhow, it's recommended to its value will be written
>>> instantly to the memory.
>>
>> A barrier doesn't guarantee speed, only ordering. Unless you can
>> measure the difference, you should not have it.
>
> Rob,
> let me have an example:
> context#1 updates outstanding_reqs variable and write(DOOR_BELL)
> context#2 upon interrupt of a request completion the following happens:
>   report completion on each one of the bits in:
>   outstanding_reqs ^ read(DOOR_BELL);
>
> 0. let's assume the DOOR_BELL = 0x1 (which means 1 active request in slot 0)
> 1. context#1: update the DOOR_BELL to be 0x3; (2 active requests: in slot
> 0 and 1)
> 2. the new value 0x3 is still not written to the DR so DORR_BELL is still
> 0x1, but outstanding_reqs is already updated = 0x3
> 3. the request in slot 0 just completed, and interrupt happens, so
> DORR_BELL is now 0 (request in slot 0 completed)
> 4. context#2: outstanding_reqs ^ read(DOOR_BELL) = 0x3 ^ 0x0 = 0x3 =>
> wrong conclusion since the request in slot 1 never completed, and actually
> never started.

Barriers alone will never solve this problem. They may narrow the
window possibly, but the problem is still there. What you have to have
is a spinlock around all accesses to both outstanding_reqs and
doorbell register. And guess what, spinlocks have appropriate barriers
to ensure visibility of what they protect. Or perhaps the h/w provides
another way to signal what slots have completed. Using the same
register for doorbell and completion status is not ideal.

Rob

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[ygardi]

> On Thu, Aug 27, 2015 at 7:11 AM,  <ygardi@codeaurora.org> wrote:
>>> On Tue, Aug 25, 2015 at 7:36 AM,  <ygardi@codeaurora.org> wrote:
>>>>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>>>>
>>>>>> Add a write memory barrier to make sure descriptors prepared are
>>>>>> actually
>>>>>> written to memory before ringing the doorbell. We have also added
>>>>>> the
>>>>>> write memory barrier after ringing the doorbell register so that
>>>>>> controller sees the new request immediately.
>>>>>>
>>>>>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>>>>>
>>>>>> ---
>>>>>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>>>>>  1 file changed, 6 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>>>>> index fef0660..876148b 100644
>>>>>> --- a/drivers/scsi/ufs/ufshcd.c
>>>>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>>>>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>>>>>> unsigned int task_tag)
>>>>>>         ufshcd_clk_scaling_start_busy(hba);
>>>>>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>>>>>         ufshcd_writel(hba, 1 << task_tag,
>>>>>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>>>>> +       /* Make sure that doorbell is committed immediately */
>>>>>> +       wmb();
>>>>>
>>>>> Is this really necessary? Is there a measurable difference?
>>>>
>>>> I'm not sure if there is a measurable difference, but as the Door-Bell
>>>> register is the one that actually responsible for the HW execution of
>>>> the
>>>> requests, anyhow, it's recommended to its value will be written
>>>> instantly to the memory.
>>>
>>> A barrier doesn't guarantee speed, only ordering. Unless you can
>>> measure the difference, you should not have it.
>>
>> Rob,
>> let me have an example:
>> context#1 updates outstanding_reqs variable and write(DOOR_BELL)
>> context#2 upon interrupt of a request completion the following happens:
>>   report completion on each one of the bits in:
>>   outstanding_reqs ^ read(DOOR_BELL);
>>
>> 0. let's assume the DOOR_BELL = 0x1 (which means 1 active request in
>> slot 0)
>> 1. context#1: update the DOOR_BELL to be 0x3; (2 active requests: in
>> slot
>> 0 and 1)
>> 2. the new value 0x3 is still not written to the DR so DORR_BELL is
>> still
>> 0x1, but outstanding_reqs is already updated = 0x3
>> 3. the request in slot 0 just completed, and interrupt happens, so
>> DORR_BELL is now 0 (request in slot 0 completed)
>> 4. context#2: outstanding_reqs ^ read(DOOR_BELL) = 0x3 ^ 0x0 = 0x3 =>
>> wrong conclusion since the request in slot 1 never completed, and
>> actually
>> never started.
>
> Barriers alone will never solve this problem. They may narrow the
> window possibly, but the problem is still there. What you have to have
> is a spinlock around all accesses to both outstanding_reqs and
> doorbell register. And guess what, spinlocks have appropriate barriers
> to ensure visibility of what they protect. Or perhaps the h/w provides
> another way to signal what slots have completed. Using the same
> register for doorbell and completion status is not ideal.
>

can i assume spin_lock_irqsave() and spin_unlock_irqrestore()
both provide barriers ? i couldn't find the barrier instruction
when following the call chain...


> Rob
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[ygardi]

>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>
>>> Add a write memory barrier to make sure descriptors prepared are
>>> actually
>>> written to memory before ringing the doorbell. We have also added the
>>> write memory barrier after ringing the doorbell register so that
>>> controller sees the new request immediately.
>>>
>>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>>
>>> ---
>>>  drivers/scsi/ufs/ufshcd.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>> index fef0660..876148b 100644
>>> --- a/drivers/scsi/ufs/ufshcd.c
>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>> @@ -833,6 +833,8 @@ void ufshcd_send_command(struct ufs_hba *hba,
>>> unsigned int task_tag)
>>>         ufshcd_clk_scaling_start_busy(hba);
>>>         __set_bit(task_tag, &hba->outstanding_reqs);
>>>         ufshcd_writel(hba, 1 << task_tag,
>>> REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>> +       /* Make sure that doorbell is committed immediately */
>>> +       wmb();
>>
>> Is this really necessary? Is there a measurable difference?
>
> I'm not sure if there is a measurable difference, but as the Door-Bell
> register is the one that actually responsible for the HW execution of the
> requests, anyhow, it's recommended to its value will be written
> instantly to the memory.
>
> Also, as the Interrupt context reads this register, and compare it to the
> SW mirroring value (hba->outstanding_reqs) in order to realize what
> requests are already completed, it's important to get the correct value
> by reading this register, otherwise we might realize a request completion
> while it was never even submitted.
>
>>
>>>  }
>>>
>>>  /**
>>> @@ -1418,6 +1420,8 @@ static int ufshcd_queuecommand(struct Scsi_Host
>>> *host, struct scsi_cmnd *cmd)
>>>                 goto out;
>>>         }
>>>
>>> +       /* Make sure descriptors are ready before ringing the doorbell
>>> */
>>> +       wmb();
>>
>> The writel for the doorbell will do a barrier first. (I didn't check
>> what exactly ufshcd_writel does, but that is why I don't like these
>> private access wrappers.)

the barrier here is important and a must.
before it we prepare descriptors.
after it we write to DOOR-BELL.
(and after the DOOR-BELL we have another one.)
if we remove it, we might get the DOOR-BELL written, before the
descriptors written.




>>
>>>         /* issue command to the controller */
>>>         spin_lock_irqsave(hba->host->host_lock, flags);
>>>         ufshcd_send_command(hba, tag);
>>> @@ -1627,6 +1631,8 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba
>>> *hba,
>>>
>>>         hba->dev_cmd.complete = &wait;
>>>
>>> +       /* Make sure descriptors are ready before ringing the doorbell
>>> */
>>> +       wmb();
>>>         spin_lock_irqsave(hba->host->host_lock, flags);
>>>         ufshcd_send_command(hba, tag);
>>>         spin_unlock_irqrestore(hba->host->host_lock, flags);
>>> --
>>> 1.8.5.2
>>>
>>> --
>>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>>> member of Code Aurora Forum, hosted by The Linux Foundation
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: [PATCH v1 14/15] scsi: ufs: commit descriptors before setting the doorbell

[Rob Herring]

On Thu, Aug 27, 2015 at 7:28 AM,  <ygardi@codeaurora.org> wrote:
>>> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>>>
>>>> Add a write memory barrier to make sure descriptors prepared are
>>>> actually
>>>> written to memory before ringing the doorbell. We have also added the
>>>> write memory barrier after ringing the doorbell register so that
>>>> controller sees the new request immediately.

[...]

>>>> +       /* Make sure descriptors are ready before ringing the doorbell
>>>> */
>>>> +       wmb();
>>>
>>> The writel for the doorbell will do a barrier first. (I didn't check
>>> what exactly ufshcd_writel does, but that is why I don't like these
>>> private access wrappers.)
>
> the barrier here is important and a must.
> before it we prepare descriptors.
> after it we write to DOOR-BELL.
> (and after the DOOR-BELL we have another one.)
> if we remove it, we might get the DOOR-BELL written, before the
> descriptors written.

If you dig into what writel does, you will see that what the code here
ends up being is:

descriptor setup
wmb()
__iomwb() -> wmb on arm64
doorbell register write

So explain why you need 2 barriers.

Barriers in a driver are a red flag. Usually they are not needed, but
sometimes they are. You have to be able to explain why if they are.
Pretty much every descriptor based DMA device works as you describe
and has the ordering problem. Because of that, the core code takes
care of this.

Rob

[PATCH v1 15/15] scsi: ufs: add wrapper for retrying sending query attribute

[Yaniv Gardi]

Sometimes queries from the device might return a failure so it is
recommended to retry sending the query, before giving up.
This change adds a wrapper to retry sending a query attribute,
in cases where we need to wait longer, before we continue,
or before reporting a failure.

Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 51 ++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 44 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 876148b..bfef67d 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1827,6 +1827,43 @@ out:
 }
 
 /**
+ * ufshcd_query_attr_retry() - API function for sending query
+ * attribute with retries
+ * @hba: per-adapter instance
+ * @opcode: attribute opcode
+ * @idn: attribute idn to access
+ * @index: index field
+ * @selector: selector field
+ * @attr_val: the attribute value after the query request
+ * completes
+ *
+ * Returns 0 for success, non-zero in case of failure
+*/
+static int ufshcd_query_attr_retry(struct ufs_hba *hba,
+	enum query_opcode opcode, enum attr_idn idn, u8 index, u8 selector,
+	u32 *attr_val)
+{
+	int ret = 0;
+	u32 retries;
+
+	 for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
+		ret = ufshcd_query_attr(hba, opcode, idn, index,
+						selector, attr_val);
+		if (ret)
+			dev_dbg(hba->dev, "%s: failed with error %d, retries %d\n",
+				__func__, ret, retries);
+		else
+			break;
+	}
+
+	if (ret)
+		dev_err(hba->dev,
+			"%s: query attribute, idn %d, failed with error %d after %d retires\n",
+			__func__, idn, ret, retries);
+	return ret;
+}
+
+/**
  * ufshcd_query_descriptor - API function for sending descriptor requests
  * hba: per-adapter instance
  * opcode: attribute opcode
@@ -3407,7 +3444,7 @@ static int ufshcd_disable_ee(struct ufs_hba *hba, u16 mask)
 
 	val = hba->ee_ctrl_mask & ~mask;
 	val &= 0xFFFF; /* 2 bytes */
-	err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+	err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
 			QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
 	if (!err)
 		hba->ee_ctrl_mask &= ~mask;
@@ -3435,7 +3472,7 @@ static int ufshcd_enable_ee(struct ufs_hba *hba, u16 mask)
 
 	val = hba->ee_ctrl_mask | mask;
 	val &= 0xFFFF; /* 2 bytes */
-	err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+	err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
 			QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
 	if (!err)
 		hba->ee_ctrl_mask |= mask;
@@ -3541,7 +3578,7 @@ static void  ufshcd_force_reset_auto_bkops(struct ufs_hba *hba)
 
 static inline int ufshcd_get_bkops_status(struct ufs_hba *hba, u32 *status)
 {
-	return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+	return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
 			QUERY_ATTR_IDN_BKOPS_STATUS, 0, 0, status);
 }
 
@@ -3604,7 +3641,7 @@ static int ufshcd_urgent_bkops(struct ufs_hba *hba)
 
 static inline int ufshcd_get_ee_status(struct ufs_hba *hba, u32 *status)
 {
-	return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+	return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
 			QUERY_ATTR_IDN_EE_STATUS, 0, 0, status);
 }
 
@@ -4360,9 +4397,9 @@ static void ufshcd_init_icc_levels(struct ufs_hba *hba)
 	dev_dbg(hba->dev, "%s: setting icc_level 0x%x",
 			__func__, hba->init_prefetch_data.icc_level);
 
-	ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
-			QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
-			&hba->init_prefetch_data.icc_level);
+	ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+		QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
+		&hba->init_prefetch_data.icc_level);
 
 	if (ret)
 		dev_err(hba->dev,
-- 
1.8.5.2

-- 
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH v1 15/15] scsi: ufs: add wrapper for retrying sending query attribute

[Rob Herring]

On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>
> Sometimes queries from the device might return a failure so it is
> recommended to retry sending the query, before giving up.
> This change adds a wrapper to retry sending a query attribute,
> in cases where we need to wait longer, before we continue,
> or before reporting a failure.

Why not just always retry? Are there cases where retrying would be a problem?


>
> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>
> ---
>  drivers/scsi/ufs/ufshcd.c | 51 ++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 44 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 876148b..bfef67d 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1827,6 +1827,43 @@ out:
>  }
>
>  /**
> + * ufshcd_query_attr_retry() - API function for sending query
> + * attribute with retries
> + * @hba: per-adapter instance
> + * @opcode: attribute opcode
> + * @idn: attribute idn to access
> + * @index: index field
> + * @selector: selector field
> + * @attr_val: the attribute value after the query request
> + * completes
> + *
> + * Returns 0 for success, non-zero in case of failure
> +*/
> +static int ufshcd_query_attr_retry(struct ufs_hba *hba,
> +       enum query_opcode opcode, enum attr_idn idn, u8 index, u8 selector,
> +       u32 *attr_val)
> +{
> +       int ret = 0;
> +       u32 retries;
> +
> +        for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
> +               ret = ufshcd_query_attr(hba, opcode, idn, index,
> +                                               selector, attr_val);
> +               if (ret)
> +                       dev_dbg(hba->dev, "%s: failed with error %d, retries %d\n",
> +                               __func__, ret, retries);
> +               else
> +                       break;
> +       }
> +
> +       if (ret)
> +               dev_err(hba->dev,
> +                       "%s: query attribute, idn %d, failed with error %d after %d retires\n",
> +                       __func__, idn, ret, retries);

The retry count will be wrong here.

> +       return ret;
> +}
> +
> +/**
>   * ufshcd_query_descriptor - API function for sending descriptor requests
>   * hba: per-adapter instance
>   * opcode: attribute opcode
> @@ -3407,7 +3444,7 @@ static int ufshcd_disable_ee(struct ufs_hba *hba, u16 mask)
>
>         val = hba->ee_ctrl_mask & ~mask;
>         val &= 0xFFFF; /* 2 bytes */
> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>         if (!err)
>                 hba->ee_ctrl_mask &= ~mask;
> @@ -3435,7 +3472,7 @@ static int ufshcd_enable_ee(struct ufs_hba *hba, u16 mask)
>
>         val = hba->ee_ctrl_mask | mask;
>         val &= 0xFFFF; /* 2 bytes */
> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>         if (!err)
>                 hba->ee_ctrl_mask |= mask;
> @@ -3541,7 +3578,7 @@ static void  ufshcd_force_reset_auto_bkops(struct ufs_hba *hba)
>
>  static inline int ufshcd_get_bkops_status(struct ufs_hba *hba, u32 *status)
>  {
> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>                         QUERY_ATTR_IDN_BKOPS_STATUS, 0, 0, status);
>  }
>
> @@ -3604,7 +3641,7 @@ static int ufshcd_urgent_bkops(struct ufs_hba *hba)
>
>  static inline int ufshcd_get_ee_status(struct ufs_hba *hba, u32 *status)
>  {
> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>                         QUERY_ATTR_IDN_EE_STATUS, 0, 0, status);
>  }
>
> @@ -4360,9 +4397,9 @@ static void ufshcd_init_icc_levels(struct ufs_hba *hba)
>         dev_dbg(hba->dev, "%s: setting icc_level 0x%x",
>                         __func__, hba->init_prefetch_data.icc_level);
>
> -       ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
> -                       QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
> -                       &hba->init_prefetch_data.icc_level);
> +       ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
> +               QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
> +               &hba->init_prefetch_data.icc_level);
>
>         if (ret)
>                 dev_err(hba->dev,
> --
> 1.8.5.2
>
> --
> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH v1 15/15] scsi: ufs: add wrapper for retrying sending query attribute

[ygardi]

> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>
>> Sometimes queries from the device might return a failure so it is
>> recommended to retry sending the query, before giving up.
>> This change adds a wrapper to retry sending a query attribute,
>> in cases where we need to wait longer, before we continue,
>> or before reporting a failure.
>
> Why not just always retry? Are there cases where retrying would be a
> problem?

There is no problem to retry whenever we encounter a query that returns
with and error.
In the code, it's recommended to replace any call to


>
>
>>
>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 51
>> ++++++++++++++++++++++++++++++++++++++++-------
>>  1 file changed, 44 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 876148b..bfef67d 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -1827,6 +1827,43 @@ out:
>>  }
>>
>>  /**
>> + * ufshcd_query_attr_retry() - API function for sending query
>> + * attribute with retries
>> + * @hba: per-adapter instance
>> + * @opcode: attribute opcode
>> + * @idn: attribute idn to access
>> + * @index: index field
>> + * @selector: selector field
>> + * @attr_val: the attribute value after the query request
>> + * completes
>> + *
>> + * Returns 0 for success, non-zero in case of failure
>> +*/
>> +static int ufshcd_query_attr_retry(struct ufs_hba *hba,
>> +       enum query_opcode opcode, enum attr_idn idn, u8 index, u8
>> selector,
>> +       u32 *attr_val)
>> +{
>> +       int ret = 0;
>> +       u32 retries;
>> +
>> +        for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
>> +               ret = ufshcd_query_attr(hba, opcode, idn, index,
>> +                                               selector, attr_val);
>> +               if (ret)
>> +                       dev_dbg(hba->dev, "%s: failed with error %d,
>> retries %d\n",
>> +                               __func__, ret, retries);
>> +               else
>> +                       break;
>> +       }
>> +
>> +       if (ret)
>> +               dev_err(hba->dev,
>> +                       "%s: query attribute, idn %d, failed with error
>> %d after %d retires\n",
>> +                       __func__, idn, ret, retries);
>
> The retry count will be wrong here.

you are correct. will be fixed in V2
>
>> +       return ret;
>> +}
>> +
>> +/**
>>   * ufshcd_query_descriptor - API function for sending descriptor
>> requests
>>   * hba: per-adapter instance
>>   * opcode: attribute opcode
>> @@ -3407,7 +3444,7 @@ static int ufshcd_disable_ee(struct ufs_hba *hba,
>> u16 mask)
>>
>>         val = hba->ee_ctrl_mask & ~mask;
>>         val &= 0xFFFF; /* 2 bytes */
>> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>>         if (!err)
>>                 hba->ee_ctrl_mask &= ~mask;
>> @@ -3435,7 +3472,7 @@ static int ufshcd_enable_ee(struct ufs_hba *hba,
>> u16 mask)
>>
>>         val = hba->ee_ctrl_mask | mask;
>>         val &= 0xFFFF; /* 2 bytes */
>> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>>         if (!err)
>>                 hba->ee_ctrl_mask |= mask;
>> @@ -3541,7 +3578,7 @@ static void  ufshcd_force_reset_auto_bkops(struct
>> ufs_hba *hba)
>>
>>  static inline int ufshcd_get_bkops_status(struct ufs_hba *hba, u32
>> *status)
>>  {
>> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>>                         QUERY_ATTR_IDN_BKOPS_STATUS, 0, 0, status);
>>  }
>>
>> @@ -3604,7 +3641,7 @@ static int ufshcd_urgent_bkops(struct ufs_hba
>> *hba)
>>
>>  static inline int ufshcd_get_ee_status(struct ufs_hba *hba, u32
>> *status)
>>  {
>> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>>                         QUERY_ATTR_IDN_EE_STATUS, 0, 0, status);
>>  }
>>
>> @@ -4360,9 +4397,9 @@ static void ufshcd_init_icc_levels(struct ufs_hba
>> *hba)
>>         dev_dbg(hba->dev, "%s: setting icc_level 0x%x",
>>                         __func__, hba->init_prefetch_data.icc_level);
>>
>> -       ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> -                       QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
>> -                       &hba->init_prefetch_data.icc_level);
>> +       ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +               QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
>> +               &hba->init_prefetch_data.icc_level);
>>
>>         if (ret)
>>                 dev_err(hba->dev,
>> --
>> 1.8.5.2
>>
>> --
>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>> member of Code Aurora Forum, hosted by The Linux Foundation
>

Re: [PATCH v1 15/15] scsi: ufs: add wrapper for retrying sending query attribute

[ygardi]

> On Aug 21, 2015 3:10 PM, "Yaniv Gardi" <ygardi@codeaurora.org> wrote:
>>
>> Sometimes queries from the device might return a failure so it is
>> recommended to retry sending the query, before giving up.
>> This change adds a wrapper to retry sending a query attribute,
>> in cases where we need to wait longer, before we continue,
>> or before reporting a failure.
>
> Why not just always retry? Are there cases where retrying would be a
> problem?

There is no problem to retry whenever we encounter a query that returns
with and error.

>
>
>>
>> Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
>>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 51
>> ++++++++++++++++++++++++++++++++++++++++-------
>>  1 file changed, 44 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 876148b..bfef67d 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -1827,6 +1827,43 @@ out:
>>  }
>>
>>  /**
>> + * ufshcd_query_attr_retry() - API function for sending query
>> + * attribute with retries
>> + * @hba: per-adapter instance
>> + * @opcode: attribute opcode
>> + * @idn: attribute idn to access
>> + * @index: index field
>> + * @selector: selector field
>> + * @attr_val: the attribute value after the query request
>> + * completes
>> + *
>> + * Returns 0 for success, non-zero in case of failure
>> +*/
>> +static int ufshcd_query_attr_retry(struct ufs_hba *hba,
>> +       enum query_opcode opcode, enum attr_idn idn, u8 index, u8
>> selector,
>> +       u32 *attr_val)
>> +{
>> +       int ret = 0;
>> +       u32 retries;
>> +
>> +        for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
>> +               ret = ufshcd_query_attr(hba, opcode, idn, index,
>> +                                               selector, attr_val);
>> +               if (ret)
>> +                       dev_dbg(hba->dev, "%s: failed with error %d,
>> retries %d\n",
>> +                               __func__, ret, retries);
>> +               else
>> +                       break;
>> +       }
>> +
>> +       if (ret)
>> +               dev_err(hba->dev,
>> +                       "%s: query attribute, idn %d, failed with error
>> %d after %d retires\n",
>> +                       __func__, idn, ret, retries);
>
> The retry count will be wrong here.

you are correct. will be fixed in V2
>
>> +       return ret;
>> +}
>> +
>> +/**
>>   * ufshcd_query_descriptor - API function for sending descriptor
>> requests
>>   * hba: per-adapter instance
>>   * opcode: attribute opcode
>> @@ -3407,7 +3444,7 @@ static int ufshcd_disable_ee(struct ufs_hba *hba,
>> u16 mask)
>>
>>         val = hba->ee_ctrl_mask & ~mask;
>>         val &= 0xFFFF; /* 2 bytes */
>> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>>         if (!err)
>>                 hba->ee_ctrl_mask &= ~mask;
>> @@ -3435,7 +3472,7 @@ static int ufshcd_enable_ee(struct ufs_hba *hba,
>> u16 mask)
>>
>>         val = hba->ee_ctrl_mask | mask;
>>         val &= 0xFFFF; /* 2 bytes */
>> -       err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +       err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>>                         QUERY_ATTR_IDN_EE_CONTROL, 0, 0, &val);
>>         if (!err)
>>                 hba->ee_ctrl_mask |= mask;
>> @@ -3541,7 +3578,7 @@ static void  ufshcd_force_reset_auto_bkops(struct
>> ufs_hba *hba)
>>
>>  static inline int ufshcd_get_bkops_status(struct ufs_hba *hba, u32
>> *status)
>>  {
>> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>>                         QUERY_ATTR_IDN_BKOPS_STATUS, 0, 0, status);
>>  }
>>
>> @@ -3604,7 +3641,7 @@ static int ufshcd_urgent_bkops(struct ufs_hba
>> *hba)
>>
>>  static inline int ufshcd_get_ee_status(struct ufs_hba *hba, u32
>> *status)
>>  {
>> -       return ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>> +       return ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
>>                         QUERY_ATTR_IDN_EE_STATUS, 0, 0, status);
>>  }
>>
>> @@ -4360,9 +4397,9 @@ static void ufshcd_init_icc_levels(struct ufs_hba
>> *hba)
>>         dev_dbg(hba->dev, "%s: setting icc_level 0x%x",
>>                         __func__, hba->init_prefetch_data.icc_level);
>>
>> -       ret = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> -                       QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
>> -                       &hba->init_prefetch_data.icc_level);
>> +       ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
>> +               QUERY_ATTR_IDN_ACTIVE_ICC_LVL, 0, 0,
>> +               &hba->init_prefetch_data.icc_level);
>>
>>         if (ret)
>>                 dev_err(hba->dev,
>> --
>> 1.8.5.2
>>
>> --
>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>> member of Code Aurora Forum, hosted by The Linux Foundation
>


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