linux-kernel - [char-misc-next v2 3/9] mei: rx flow control counter

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Date:	Tue, 26 Jul 2016 01:06:03 +0300
From:	Tomas Winkler <tomas.winkler@...el.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Alexander Usyskin <alexander.usyskin@...el.com>,
	linux-kernel@...r.kernel.org,
	Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next v2 3/9] mei: rx flow control counter

From: Alexander Usyskin <alexander.usyskin@...el.com>

Use RX flow control counter in the host client structure to
track the number of simultaneous outstanding reads.
This eliminates search in queues and makes ground for
enabling for parallel read.

Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
V2: resend
 drivers/misc/mei/amthif.c  |  1 +
 drivers/misc/mei/client.c  | 40 +++++++++++++---------------------------
 drivers/misc/mei/mei_dev.h |  4 ++--
 3 files changed, 16 insertions(+), 29 deletions(-)

diff --git a/drivers/misc/mei/amthif.c b/drivers/misc/mei/amthif.c
index 26568c5beb25..227fd5a816a6 100644
--- a/drivers/misc/mei/amthif.c
+++ b/drivers/misc/mei/amthif.c
@@ -202,6 +202,7 @@ static int mei_amthif_read_start(struct mei_cl *cl, const struct file *file)
 		return -ENOMEM;
 
 	list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
+	cl->rx_flow_ctrl_creds++;
 
 	dev->iamthif_state = MEI_IAMTHIF_READING;
 	cl->fp = cb->fp;
diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index 05cacc3e718f..ded11de90a26 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -735,6 +735,7 @@ void mei_cl_set_disconnected(struct mei_cl *cl)
 	mei_io_list_flush(&dev->ctrl_wr_list, cl);
 	mei_cl_wake_all(cl);
 	cl->mei_flow_ctrl_creds = 0;
+	cl->rx_flow_ctrl_creds = 0;
 	cl->timer_count = 0;
 
 	if (!cl->me_cl)
@@ -1409,25 +1410,6 @@ out:
 }
 
 /**
- * mei_cl_is_read_fc_cb - check if read cb is waiting for flow control
- *                        for given host client
- *
- * @cl: host client
- *
- * Return: true, if found at least one cb.
- */
-static bool mei_cl_is_read_fc_cb(struct mei_cl *cl)
-{
-	struct mei_device *dev = cl->dev;
-	struct mei_cl_cb *cb;
-
-	list_for_each_entry(cb, &dev->ctrl_wr_list.list, list)
-		if (cb->fop_type == MEI_FOP_READ && cb->cl == cl)
-			return true;
-	return false;
-}
-
-/**
  * mei_cl_read_start - the start read client message function.
  *
  * @cl: host client
@@ -1450,10 +1432,6 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length, const struct file *fp)
 	if (!mei_cl_is_connected(cl))
 		return -ENODEV;
 
-	/* HW currently supports only one pending read */
-	if (!list_empty(&cl->rd_pending) || mei_cl_is_read_fc_cb(cl))
-		return -EBUSY;
-
 	if (!mei_me_cl_is_active(cl->me_cl)) {
 		cl_err(dev, cl, "no such me client\n");
 		return  -ENOTTY;
@@ -1462,12 +1440,18 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length, const struct file *fp)
 	if (mei_cl_is_fixed_address(cl))
 		return 0;
 
+	/* HW currently supports only one pending read */
+	if (cl->rx_flow_ctrl_creds)
+		return -EBUSY;
+
 	/* always allocate at least client max message */
 	length = max_t(size_t, length, mei_cl_mtu(cl));
 	cb = mei_cl_alloc_cb(cl, length, MEI_FOP_READ, fp);
 	if (!cb)
 		return -ENOMEM;
 
+	list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
+
 	rets = pm_runtime_get(dev->dev);
 	if (rets < 0 && rets != -EINPROGRESS) {
 		pm_runtime_put_noidle(dev->dev);
@@ -1475,16 +1459,15 @@ int mei_cl_read_start(struct mei_cl *cl, size_t length, const struct file *fp)
 		goto nortpm;
 	}
 
+	rets = 0;
 	if (mei_hbuf_acquire(dev)) {
 		rets = mei_hbm_cl_flow_control_req(dev, cl);
 		if (rets < 0)
 			goto out;
 
-		list_add_tail(&cb->list, &cl->rd_pending);
-	} else {
-		rets = 0;
-		list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
+		list_move_tail(&cb->list, &cl->rd_pending);
 	}
+	cl->rx_flow_ctrl_creds++;
 
 out:
 	cl_dbg(dev, cl, "rpm: autosuspend\n");
@@ -1732,6 +1715,9 @@ void mei_cl_complete(struct mei_cl *cl, struct mei_cl_cb *cb)
 
 	case MEI_FOP_READ:
 		list_add_tail(&cb->list, &cl->rd_completed);
+		if (!mei_cl_is_fixed_address(cl) &&
+		    !WARN_ON(!cl->rx_flow_ctrl_creds))
+			cl->rx_flow_ctrl_creds--;
 		if (!mei_cl_bus_rx_event(cl))
 			wake_up_interruptible(&cl->rx_wait);
 		break;
diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h
index aaefbc87c2fc..8bdb28054423 100644
--- a/drivers/misc/mei/mei_dev.h
+++ b/drivers/misc/mei/mei_dev.h
@@ -203,8 +203,8 @@ struct mei_cl_cb {
  * @fp: file associated with client
  * @host_client_id: host id
  * @mei_flow_ctrl_creds: transmit flow credentials
+ * @rx_flow_ctrl_creds: receive flow credentials
  * @timer_count:  watchdog timer for operation completion
- * @reserved: reserved for alignment
  * @notify_en: notification - enabled/disabled
  * @notify_ev: pending notification event
  * @writing_state: state of the tx
@@ -227,8 +227,8 @@ struct mei_cl {
 	const struct file *fp;
 	u8 host_client_id;
 	u8 mei_flow_ctrl_creds;
+	u8 rx_flow_ctrl_creds;
 	u8 timer_count;
-	u8 reserved;
 	u8 notify_en;
 	u8 notify_ev;
 	enum mei_file_transaction_states writing_state;
-- 
2.7.4