[PATCH 2/3] net cpsw: fix rx stability under heavy network load

[Sascha Hauer]

On Wed, Apr 30, 2014 at 10:32:02AM +0200, chf.fritz at googlemail.com wrote:
> From: Christoph Fritz <chf.fritz at googlemail.com>
> 
> RX DMA Head Descriptor Pointer can get 0 when there is a lot of traffic,
> which results in a timeout error. A good way to provoke this error is by
> sending lots of ARP requests. This patch makes sure that the RX DMA Head
> Descriptor Pointer is set.
> 
> The origin driver, from which this is derived, already contains this fix.
> 
> Signed-off-by: Christoph Fritz <chf.fritz at googlemail.com>

Nice fix, thanks. I also stumbled upon this.

Applied

Sascha

> ---
>  drivers/net/cpsw.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/cpsw.c b/drivers/net/cpsw.c
> index 52adf50..ec3263d 100644
> --- a/drivers/net/cpsw.c
> +++ b/drivers/net/cpsw.c
> @@ -741,8 +741,13 @@ static int cpdma_process(struct cpsw_priv *priv, struct cpdma_chan *chan,
>  	if (buffer)
>  		*buffer = (void *)readl(&desc->sw_buffer);
>  
> -	if (status & CPDMA_DESC_OWNER)
> +	if (status & CPDMA_DESC_OWNER) {
> +		if (readl(chan->hdp) == 0) {
> +			if (readl(&desc->hw_mode) & CPDMA_DESC_OWNER)
> +				writel((u32)desc, chan->hdp);
> +		}
>  		return -EBUSY;
> +	}
>  
>  	chan->head = (void *)readl(&desc->hw_next);
>  
> -- 
> 1.7.10.4
> 
> 
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