When chaining descriptors to the end of a cpdma queue, there is a chance that the cpdma engine has already traversed the last descriptor and signalled an end-of-queue. The original cpdma code detected this condition and requeued descriptors on submission.
With this patch, an early end-of-queue condition is detected on descriptor submission as well. This is necessary on davinci style emac controllers, and prevents transmit timeouts when sending out a burst of packets. Signed-off-by: Cyril Chemparathy <[email protected]> Signed-off-by: Michael Williamson <[email protected]> Signed-off-by: Caglar Akyuz <[email protected]> --- drivers/net/davinci_cpdma.c | 12 ++++++++++-- drivers/net/davinci_cpdma.h | 1 + 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/net/davinci_cpdma.c b/drivers/net/davinci_cpdma.c index ab7ecd7..abc2b14 100644 --- a/drivers/net/davinci_cpdma.c +++ b/drivers/net/davinci_cpdma.c @@ -488,6 +488,7 @@ static void __cpdma_chan_submit(struct cpdma_chan *chan, struct cpdma_desc __iomem *prev = chan->tail; struct cpdma_desc_pool *pool = ctlr->pool; dma_addr_t desc_dma; + u32 mode; desc_dma = desc_phys(pool, desc); @@ -507,8 +508,10 @@ static void __cpdma_chan_submit(struct cpdma_chan *chan, chan->stats.tail_enqueue++; /* next check if EOQ has been triggered already */ - if (desc_read(prev, hw_mode) & CPDMA_DESC_EOQ && - chan->state == CPDMA_STATE_ACTIVE) { + mode = desc_read(prev, hw_mode); + if (((mode & (CPDMA_DESC_EOQ | CPDMA_DESC_OWNER)) == CPDMA_DESC_EOQ) && + (chan->state == CPDMA_STATE_ACTIVE)) { + desc_write(prev, hw_mode, mode & ~CPDMA_DESC_EOQ); chan_write(chan, hdp, desc_dma); chan->stats.misqueued++; } @@ -618,6 +621,11 @@ static int __cpdma_chan_process(struct cpdma_chan *chan) chan->count--; chan->stats.good_dequeue++; + if (status & CPDMA_DESC_EOQ) { + chan->stats.requeue++; + chan_write(chan, hdp, desc_phys(pool, chan->head)); + } + spin_unlock_irqrestore(&chan->lock, flags); __cpdma_chan_free(chan, desc, outlen, status); diff --git a/drivers/net/davinci_cpdma.h b/drivers/net/davinci_cpdma.h index d50ee35..9baacca 100644 --- a/drivers/net/davinci_cpdma.h +++ b/drivers/net/davinci_cpdma.h @@ -56,6 +56,7 @@ struct cpdma_chan_stats { u32 empty_dequeue; u32 busy_dequeue; u32 good_dequeue; + u32 requeue; u32 teardown_dequeue; }; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
