Hi,
Here's a little patch to make sure tranfer_buffer is always if DMA
is temporarily unavailable. I ran into this with tusb6010 that
currently can only do limited DMA. This fixes a problem of connecting
storage devices and doing mixed DMA/PIO access.
Regards,
Tony
From: Tony Lindgren <[EMAIL PROTECTED]>
Subject: USB: Always map transfer_buffer
In case a DMA channel for an endpoint is temporarily
unavailable, the host controller driver may still be
able to transfer the data using PIO. Without this patch
the transfer_buffer is not mapped, and host controller
does not know what to use for PIO.
Signed-off-by: Tony Lindgren <[EMAIL PROTECTED]>
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -412,16 +412,18 @@ int usb_sg_init (
io->urbs [i]->status = -EINPROGRESS;
io->urbs [i]->actual_length = 0;
+ /*
+ * Always have PIO buffer available in case a DMA channel
+ * is temporarily unavailable for the given EP in the host
+ * controller.
+ */
+ io->urbs [i]->transfer_buffer =
+ page_address (sg [i].page) + sg [i].offset;
if (dma) {
- /* hc may use _only_ transfer_dma */
io->urbs [i]->transfer_dma = sg_dma_address (sg + i);
len = sg_dma_len (sg + i);
- } else {
- /* hc may use _only_ transfer_buffer */
- io->urbs [i]->transfer_buffer =
- page_address (sg [i].page) + sg [i].offset;
+ } else
len = sg [i].length;
- }
if (length) {
len = min_t (unsigned, len, length);
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