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authorDaniel Mack <zonque@gmail.com>2014-05-26 14:52:34 +0200
committerVinod Koul <vinod.koul@intel.com>2014-07-01 12:15:48 +0530
commit13bbfb5c4eb4fc85bf977245f9b3624df0187184 (patch)
tree87d101762d6454fcb9091dd7b76c8bbc59f7f625
parent4c834452aad01531db949414f94f817a86348d59 (diff)
downloadlinux-13bbfb5c4eb4fc85bf977245f9b3624df0187184.tar.gz
dma: cppi41: handle 0-length packets
When a 0-length packet is received on the bus, desc->pd0 yields 1, which confuses the driver's users. This information is clearly wrong and not in accordance to the datasheet, but it's been observed on an AM335x board, very reproducible. Fix this by looking at bit 19 in PD2 of the completed packet. This bit will tell us if a zero-length packet was received on a queue. If it's set, ignore the value in PD0 and report a total length of 0 instead. Signed-off-by: Daniel Mack <zonque@gmail.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
-rw-r--r--drivers/dma/cppi41.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
index d028f36ae65..8f8b0b60887 100644
--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -86,6 +86,9 @@
#define USBSS_IRQ_PD_COMP (1 << 2)
+/* Packet Descriptor */
+#define PD2_ZERO_LENGTH (1 << 19)
+
struct cppi41_channel {
struct dma_chan chan;
struct dma_async_tx_descriptor txd;
@@ -307,7 +310,7 @@ static irqreturn_t cppi41_irq(int irq, void *data)
__iormb();
while (val) {
- u32 desc;
+ u32 desc, len;
q_num = __fls(val);
val &= ~(1 << q_num);
@@ -319,9 +322,13 @@ static irqreturn_t cppi41_irq(int irq, void *data)
q_num, desc);
continue;
}
- c->residue = pd_trans_len(c->desc->pd6) -
- pd_trans_len(c->desc->pd0);
+ if (c->desc->pd2 & PD2_ZERO_LENGTH)
+ len = 0;
+ else
+ len = pd_trans_len(c->desc->pd0);
+
+ c->residue = pd_trans_len(c->desc->pd6) - len;
dma_cookie_complete(&c->txd);
c->txd.callback(c->txd.callback_param);
}