xhci: Don't use soft retry if slot id > 0
diff mbox series

Message ID 20191013003313.3497-1-bernhard.gebetsberger@gmx.at
State New
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Series
  • xhci: Don't use soft retry if slot id > 0
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Commit Message

Bernhard Gebetsberger Oct. 13, 2019, 12:33 a.m. UTC
According to the xhci specification(chapter 4.6.8.1) soft retry
shouldn't be used if the slot id is higher than 0. Currently some usb
devices break on some systems because soft retry is being used when
there is a transaction error, without checking the slot id.

Fixes: f8f80be501aa ("xhci: Use soft retry to recover faster from
transaction errors")

Signed-off-by: Bernhard Gebetsberger <bernhard.gebetsberger@gmx.at>
---
 drivers/usb/host/xhci-ring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--
2.23.0

Comments

Mathias Nyman Oct. 14, 2019, 8:06 a.m. UTC | #1
On 13.10.2019 3.33, Bernhard Gebetsberger wrote:
> According to the xhci specification(chapter 4.6.8.1) soft retry
> shouldn't be used if the slot id is higher than 0. Currently some usb
> devices break on some systems because soft retry is being used when
> there is a transaction error, without checking the slot id.
> 
That is not correct

Specs say that soft retry should not be used if we are dealing with a
FS/LS device behind a HS hub, this can be checked from the "TT Hub Slot ID"
field in the slot context, which we do.

In xhci all devices have a slot id, so this change would prevent
soft retry almost completely.

Specs 4.6.8.1:
"Soft Retry attempts shall not be performed if the device is behind a
TT in a HS Hub (i.e. TT Hub Slot ID > ‘0’)."

-Mathias
Bernhard Gebetsberger Oct. 14, 2019, 9:17 a.m. UTC | #2
Am 14.10.19 um 10:06 schrieb Mathias Nyman:
> On 13.10.2019 3.33, Bernhard Gebetsberger wrote:
>> According to the xhci specification(chapter 4.6.8.1) soft retry
>> shouldn't be used if the slot id is higher than 0. Currently some usb
>> devices break on some systems because soft retry is being used when
>> there is a transaction error, without checking the slot id.
>>
> That is not correct
>
> Specs say that soft retry should not be used if we are dealing with a
> FS/LS device behind a HS hub, this can be checked from the "TT Hub Slot ID"
> field in the slot context, which we do.
>
> In xhci all devices have a slot id, so this change would prevent
> soft retry almost completely.
>
> Specs 4.6.8.1:
> "Soft Retry attempts shall not be performed if the device is behind a
> TT in a HS Hub (i.e. TT Hub Slot ID > ‘0’)."
>
> -Mathias
Thanks for the explanation, I have misunderstood that part from the xhci

spec. Sorry.

- Bernhard

Patch
diff mbox series

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 85ceb43e3405..5fa06189068d 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2270,7 +2270,7 @@  static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 		break;
 	case COMP_USB_TRANSACTION_ERROR:
 		if ((ep_ring->err_count++ > MAX_SOFT_RETRY) ||
-		    le32_to_cpu(slot_ctx->tt_info) & TT_SLOT)
+		    le32_to_cpu(slot_ctx->tt_info) & TT_SLOT || slot_id > 0)
 			break;
 		*status = 0;
 		xhci_cleanup_halted_endpoint(xhci, slot_id, ep_index,