On Wed, Sep 28, 2016 at 10:12:42PM -0400, Sinan Kaya wrote:
> Getting ready for the MSI interrupts. The pending_tre_count is used
> in the interrupt handler to make sure all outstanding requests are
> serviced.
>
> Making it atomic so that it can be updated from multiple contexts.
How is it multiple contexts? It's either existing context of MSI, not both!
>
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> ---
> drivers/dma/qcom/hidma.h | 2 +-
> drivers/dma/qcom/hidma_dbg.c | 3 ++-
> drivers/dma/qcom/hidma_ll.c | 13 ++++++-------
> 3 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/dma/qcom/hidma.h b/drivers/dma/qcom/hidma.h
> index e52e207..3f2ddd4 100644
> --- a/drivers/dma/qcom/hidma.h
> +++ b/drivers/dma/qcom/hidma.h
> @@ -58,7 +58,7 @@ 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 fa827e5..87db285 100644
> --- 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 3224f24..29fef4f 100644
> --- 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);
> @@ -321,7 +320,7 @@ 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;
> @@ -548,7 +547,7 @@ 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);
> @@ -654,7 +653,7 @@ 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;
> @@ -816,7 +815,7 @@ 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);
> --
> 1.9.1
>
--
~Vinod
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