[Sound-open-firmware] [PATCH 4/4] Fix DMA host offset calculation.

[Pierre-Louis Bossart]

On 11/09/2017 12:17 AM, yan.wang at linux.intel.com wrote:
> From: Yan Wang <yan.wang at linux.intel.com>
>
> 1. "size" should not be considered twice.
> 2. Change host_offset to uint32_t type.
>
> Signed-off-by: Yan Wang <yan.wang at linux.intel.com>
> ---
>   src/include/reef/dma-trace.h | 2 +-
>   src/lib/dma-trace.c          | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/include/reef/dma-trace.h b/src/include/reef/dma-trace.h
> index 12d0956..641a4dc 100644
> --- a/src/include/reef/dma-trace.h
> +++ b/src/include/reef/dma-trace.h
> @@ -56,7 +56,7 @@ struct dma_trace_data {
>   	struct dma_sg_config config;
>   	struct dma_trace_buf dmatb;
>   	struct dma_copy dc;
> -	int32_t host_offset;
> +	uint32_t host_offset;
>   	uint32_t host_size;
>   	struct work dmat_work;
>   	uint32_t enabled;
> diff --git a/src/lib/dma-trace.c b/src/lib/dma-trace.c
> index 5885037..249e18b 100644
> --- a/src/lib/dma-trace.c
> +++ b/src/lib/dma-trace.c
> @@ -90,7 +90,7 @@ static uint64_t trace_work(void *data, uint64_t delay)
>   
>   	/* update host pointer and check for wrap */
>   	d->host_offset += size;
> -	if (d->host_offset + size >= d->host_size)
> +	if (d->host_offset >= d->host_size)
>   		d->host_offset = 0;
this code pattern is present multiple times in the DMA handling code.
I wonder if this is correct when the > condition is true? That'd mean 
some overrun happened or that some bytes have been lost.
Shouldn't this be an exact == condition in there is a true wrap?
>   
>   	/* update local pointer and check for wrap */