Supposed DMA cross 4k bounder problem should be fixed at DEV_VER_V2, but
still met problem when do ISO transfer if sg enabled.
Data pattern likes below when sg enabled, package size is 1k and mult is 2
[UVC Header(8B) ] [data(3k - 8)] ...
The received data at offset 0xd000 will get 0xc000 data, len 0x70. Error
happen position as below pattern:
0xd000: wrong
0xe000: wrong
0xf000: correct
0x10000: wrong
0x11000: wrong
0x12000: correct
...
To avoid DMA cross 4k bounder at ISO transfer, reduce burst len according
to start DMA address's alignment.
Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
drivers/usb/cdns3/cdns3-gadget.c | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 4c6893af22dde..aeca902ab6cc4 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -1120,6 +1120,7 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep,
u32 togle_pcs = 1;
int sg_iter = 0;
int num_trb_req;
+ int trb_burst;
int num_trb;
int address;
u32 control;
@@ -1243,7 +1244,36 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep,
total_tdl += DIV_ROUND_UP(length,
priv_ep->endpoint.maxpacket);
- trb->length |= cpu_to_le32(TRB_BURST_LEN(priv_ep->trb_burst_size) |
+ trb_burst = priv_ep->trb_burst_size;
+
+ /*
+ * Supposed DMA cross 4k bounder problem should be fixed at DEV_VER_V2, but still
+ * met problem when do ISO transfer if sg enabled.
+ *
+ * Data pattern likes below when sg enabled, package size is 1k and mult is 2
+ * [UVC Header(8B) ] [data(3k - 8)] ...
+ *
+ * The received data at offset 0xd000 will get 0xc000 data, len 0x70. Error happen
+ * as below pattern:
+ * 0xd000: wrong
+ * 0xe000: wrong
+ * 0xf000: correct
+ * 0x10000: wrong
+ * 0x11000: wrong
+ * 0x12000: correct
+ * ...
+ *
+ * But it is still unclear about why error have not happen below 0xd000, it should
+ * cross 4k bounder. But anyway, the below code can fix this problem.
+ *
+ * To avoid DMA cross 4k bounder at ISO transfer, reduce burst len according to 16.
+ */
+ if (priv_ep->type == USB_ENDPOINT_XFER_ISOC && priv_dev->dev_ver <= DEV_VER_V2)
+ if (ALIGN_DOWN(trb->buffer, SZ_4K) !=
+ ALIGN_DOWN(trb->buffer + length, SZ_4K))
+ trb_burst = 16;
+
+ trb->length |= cpu_to_le32(TRB_BURST_LEN(trb_burst) |
TRB_LEN(length));
pcs = priv_ep->pcs ? TRB_CYCLE : 0;
--
2.34.1
