ChangeSet 1.1276.1.58, 2003/08/28 10:53:17-07:00, [EMAIL PROTECTED]
[PATCH] USB: net2280, patch dma chains
One person working on a mass-storage driver (the usb protocol
side, not the block subsystem side) ran into a bug in how a
bit of net2280 dma automagic was handled.
This patch fixes it by calling existing dma chain patchup
code when the dma engine was forced to "hiccup" by having
a not-yet-valid entry in it. The hiccup is needed in this
case since the IN data stage mustn't terminate with a
short transfer (zero length packet); but the status stage
is always a short packet. The "terminate with short packet"
bit is endpoint state, not request state, so IN dma queues
sometimes need this kind of fixup.
drivers/usb/gadget/net2280.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+)
diff -Nru a/drivers/usb/gadget/net2280.c b/drivers/usb/gadget/net2280.c
--- a/drivers/usb/gadget/net2280.c Tue Sep 2 12:42:59 2003
+++ b/drivers/usb/gadget/net2280.c Tue Sep 2 12:42:59 2003
@@ -2432,6 +2432,28 @@
if ((tmp & (1 << DMA_SCATTER_GATHER_ENABLE)) == 0
|| (tmp & (1 << DMA_ENABLE)) == 0)
restart_dma (ep);
+#ifdef USE_DMA_CHAINING
+ else if (ep->desc->bEndpointAddress & USB_DIR_IN) {
+ struct net2280_request *req;
+ u32 dmacount;
+
+ /* the descriptor at the head of the chain
+ * may still have VALID_BIT clear; that's
+ * used to trigger changing DMA_FIFO_VALIDATE
+ * (affects automagic zlp writes).
+ */
+ req = list_entry (ep->queue.next,
+ struct net2280_request, queue);
+ dmacount = req->td->dmacount;
+ dmacount &= __constant_cpu_to_le32 (
+ (1 << VALID_BIT)
+ | DMA_BYTE_COUNT_MASK);
+ if (dmacount && (dmacount & valid_bit) == 0) {
+ stop_dma (ep->dma);
+ restart_dma (ep);
+ }
+ }
+#endif
}
ep->irqs++;
}
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