ENGR00291729 PXP: remove a mutex lock from pxp channel

This mutex lock is no longer necessary in PXP dma driver. After
the commit "ENGR00291400 PXP: Organize PXP task queue to be FIFO",
protection fields can be protected by the spin lock in PXP channel
now.

Signed-off-by: Fancy Fang <B47543@freescale.com>

2 files changed, 11 insertions, 12 deletions

diff --git a/drivers/dma/pxp/pxp_dma_v2.c b/drivers/dma/pxp/pxp_dma_v2.c
index 55f0a5a6adf9..18d8279425da 100644
--- a/drivers/dma/pxp/pxp_dma_v2.c
+++ b/drivers/dma/pxp/pxp_dma_v2.c
@@ -1155,7 +1155,8 @@ static dma_cookie_t pxp_tx_submit(struct dma_async_tx_descriptor *tx)
 
         dev_dbg(&pxp_chan->dma_chan.dev->device, "received TX\n");
 
-        mutex_lock(&pxp_chan->chan_mutex);
+        /* pxp_chan->lock can be taken under ichan->lock, but not v.v. */
+        spin_lock_irqsave(&pxp_chan->lock, flags);
 
         cookie = pxp_chan->dma_chan.cookie;
 
@@ -1166,9 +1167,6 @@ static dma_cookie_t pxp_tx_submit(struct dma_async_tx_descriptor *tx)
         pxp_chan->dma_chan.cookie = cookie;
         tx->cookie = cookie;
 
-        /* pxp_chan->lock can be taken under ichan->lock, but not v.v. */
-        spin_lock_irqsave(&pxp_chan->lock, flags);
-
         /* Here we add the tx descriptor to our PxP task queue. */
         list_add_tail(&desc->list, &pxp_chan->queue);
 
@@ -1176,7 +1174,6 @@ static dma_cookie_t pxp_tx_submit(struct dma_async_tx_descriptor *tx)
 
         dev_dbg(&pxp_chan->dma_chan.dev->device, "done TX\n");
 
-        mutex_unlock(&pxp_chan->chan_mutex);
         return cookie;
 }
 
@@ -1385,15 +1382,16 @@ static void __pxp_terminate_all(struct dma_chan *chan)
 static int pxp_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                         unsigned long arg)
 {
+        unsigned long flags;
         struct pxp_channel *pxp_chan = to_pxp_channel(chan);
 
         /* Only supports DMA_TERMINATE_ALL */
         if (cmd != DMA_TERMINATE_ALL)
                 return -ENXIO;
 
-        mutex_lock(&pxp_chan->chan_mutex);
+        spin_lock_irqsave(&pxp_chan->lock, flags);
         __pxp_terminate_all(chan);
-        mutex_unlock(&pxp_chan->chan_mutex);
+        spin_unlock_irqrestore(&pxp_chan->lock, flags);
 
         return 0;
 }
@@ -1429,15 +1427,16 @@ err_chan:
 
 static void pxp_free_chan_resources(struct dma_chan *chan)
 {
+        unsigned long flags;
         struct pxp_channel *pxp_chan = to_pxp_channel(chan);
 
-        mutex_lock(&pxp_chan->chan_mutex);
+        spin_lock_irqsave(&pxp_chan->lock, flags);
 
         __pxp_terminate_all(chan);
 
         pxp_chan->status = PXP_CHANNEL_FREE;
 
-        mutex_unlock(&pxp_chan->chan_mutex);
+        spin_unlock_irqrestore(&pxp_chan->lock, flags);
 }
 
 static enum dma_status pxp_tx_status(struct dma_chan *chan,
@@ -1595,7 +1594,6 @@ static int pxp_dma_init(struct pxps *pxp)
                 struct dma_chan *dma_chan = &pxp_chan->dma_chan;
 
                 spin_lock_init(&pxp_chan->lock);
-                mutex_init(&pxp_chan->chan_mutex);
 
                 /* Only one EOF IRQ for PxP, shared by all channels */
                 pxp_chan->eof_irq = pxp->irq;
diff --git a/include/linux/pxp_dma.h b/include/linux/pxp_dma.h
index 61b3e7de4c57..613d89f143f9 100644
--- a/include/linux/pxp_dma.h
+++ b/include/linux/pxp_dma.h
@@ -47,8 +47,9 @@ struct pxp_channel {
         struct pxp_tx_desc *desc;       /* allocated tx-descriptors */
         struct list_head queue; /* queued tx-descriptors */
         struct list_head list;  /* track queued channel number */
-        spinlock_t lock;        /* protects sg[0,1], queue */
-        struct mutex chan_mutex;        /* protects status, cookie, free_list */
+        spinlock_t lock;        /* protects sg[0,1], queue,
+                                 * status, cookie, free_list
+                                 */
         int active_buffer;
         unsigned int eof_irq;
         char eof_name[16];      /* EOF IRQ name for request_irq()  */