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 <cyril@xxxxxx>
Signed-off-by: Michael Williamson <michael.williamson@xxxxxxxxxxxxxxxx>
Signed-off-by: Caglar Akyuz <caglarakyuz@xxxxxxxxx>
---
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 majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
