dmaengine: qcom_hidma: make pending_tre_count atomic

Getting ready for the MSI interrupts. The pending_tre_count is used
in the interrupt handler to make sure all outstanding requests are
serviced.

The driver will allocate 11 MSI interrupts. Each MSI interrupt can be
assigned to a different CPU. Then, we have a race condition for common
variables as they share the same interrupt handler with a different
cause bit and they can potentially be executed in parallel. Making this
variable atomic so that it can be updated from multiple processor
contexts.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/qcom/hidma.h b/drivers/dma/qcom/hidma.h
index de61764..181f7e0 100644 (file)
--- a/drivers/dma/qcom/hidma.h
+++ b/drivers/dma/qcom/hidma.h
@@ -59,7 +59,7 @@ struct hidma_lldev {
        void __iomem *evca;             /* Event Channel address          */
        struct hidma_tre
                **pending_tre_list;     /* Pointers to pending TREs       */
-       s32 pending_tre_count;          /* Number of TREs pending         */
+       atomic_t pending_tre_count;     /* Number of TREs pending         */
 
        void *tre_ring;                 /* TRE ring                       */
        dma_addr_t tre_dma;             /* TRE ring to be shared with HW  */

diff --git a/drivers/dma/qcom/hidma_dbg.c b/drivers/dma/qcom/hidma_dbg.c
index 3d83b99..3bdcb80 100644 (file)
--- a/drivers/dma/qcom/hidma_dbg.c
+++ b/drivers/dma/qcom/hidma_dbg.c
@@ -74,7 +74,8 @@ static void hidma_ll_devstats(struct seq_file *s, void *llhndl)
        seq_printf(s, "tre_ring_handle=%pap\n", &lldev->tre_dma);
        seq_printf(s, "tre_ring_size = 0x%x\n", lldev->tre_ring_size);
        seq_printf(s, "tre_processed_off = 0x%x\n", lldev->tre_processed_off);
-       seq_printf(s, "pending_tre_count=%d\n", lldev->pending_tre_count);
+       seq_printf(s, "pending_tre_count=%d\n",
+                       atomic_read(&lldev->pending_tre_count));
        seq_printf(s, "evca=%p\n", lldev->evca);
        seq_printf(s, "evre_ring=%p\n", lldev->evre_ring);
        seq_printf(s, "evre_ring_handle=%pap\n", &lldev->evre_dma);

diff --git a/drivers/dma/qcom/hidma_ll.c b/drivers/dma/qcom/hidma_ll.c
index e605c90..114409e 100644 (file)
--- a/drivers/dma/qcom/hidma_ll.c
+++ b/drivers/dma/qcom/hidma_ll.c
@@ -218,10 +218,9 @@ static int hidma_post_completed(struct hidma_lldev *lldev, int tre_iterator,
         * Keep track of pending TREs that SW is expecting to receive
         * from HW. We got one now. Decrement our counter.
         */
-       lldev->pending_tre_count--;
-       if (lldev->pending_tre_count < 0) {
+       if (atomic_dec_return(&lldev->pending_tre_count) < 0) {
                dev_warn(lldev->dev, "tre count mismatch on completion");
-               lldev->pending_tre_count = 0;
+               atomic_set(&lldev->pending_tre_count, 0);
        }
 
        spin_unlock_irqrestore(&lldev->lock, flags);
@@ -328,7 +327,7 @@ void hidma_cleanup_pending_tre(struct hidma_lldev *lldev, u8 err_info,
        u32 tre_read_off;
 
        tre_iterator = lldev->tre_processed_off;
-       while (lldev->pending_tre_count) {
+       while (atomic_read(&lldev->pending_tre_count)) {
                if (hidma_post_completed(lldev, tre_iterator, err_info,
                                         err_code))
                        break;
@@ -555,7 +554,7 @@ void hidma_ll_queue_request(struct hidma_lldev *lldev, u32 tre_ch)
        tre->err_code = 0;
        tre->err_info = 0;
        tre->queued = 1;
-       lldev->pending_tre_count++;
+       atomic_inc(&lldev->pending_tre_count);
        lldev->tre_write_offset = (lldev->tre_write_offset + HIDMA_TRE_SIZE)
                                        % lldev->tre_ring_size;
        spin_unlock_irqrestore(&lldev->lock, flags);
@@ -650,7 +649,7 @@ int hidma_ll_setup(struct hidma_lldev *lldev)
        u32 val;
        u32 nr_tres = lldev->nr_tres;
 
-       lldev->pending_tre_count = 0;
+       atomic_set(&lldev->pending_tre_count, 0);
        lldev->tre_processed_off = 0;
        lldev->evre_processed_off = 0;
        lldev->tre_write_offset = 0;
@@ -831,7 +830,7 @@ int hidma_ll_uninit(struct hidma_lldev *lldev)
        tasklet_kill(&lldev->task);
        memset(lldev->trepool, 0, required_bytes);
        lldev->trepool = NULL;
-       lldev->pending_tre_count = 0;
+       atomic_set(&lldev->pending_tre_count, 0);
        lldev->tre_write_offset = 0;
 
        rc = hidma_ll_reset(lldev);