This reverts a previously submitted patch where the slow retransmit was removed.
Previously, the max3421 driver would immediately retry transmissions
indefinitely
upon receiving a NAK response, leading to potential stalls.
This patch re-introduces a limit (`NAK_MAX_FAST_RETRANSMITS`) on how
many times a
request is retransmitted immediately. After reaching this limit, the driver
falls back to a slower retransmit strategy using `max3421_slow_retransmit()`.
This improves robustness when dealing with unresponsive USB devices.
Signed-off-by: Matt Lee <matt@xxxxxxxxxx>
---
drivers/usb/host/max3421-hcd.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/usb/host/max3421-hcd.c b/drivers/usb/host/max3421-hcd.c
index 1234567..abcdef0 100644
--- a/drivers/usb/host/max3421-hcd.c
+++ b/drivers/usb/host/max3421-hcd.c
@@ -72,6 +72,12 @@
#define USB_MAX_FRAME_NUMBER 0x7ff
#define USB_MAX_RETRIES 3 /* # of retries before error is reported */
+/*
+ * Max. # of times we're willing to retransmit a request immediately in
+ * response to a NAK. Afterwards, we fall back on trying once a frame.
+ */
+#define NAK_MAX_FAST_RETRANSMITS 2
+
#define POWER_BUDGET 500 /* in mA; use 8 for low-power port testing */
/* Port-change mask: */
@@ -924,8 +930,11 @@ max3421_handle_error(struct usb_hcd *hcd
* Device wasn't ready for data or has no data
* available: retry the packet again.
*/
+ if (max3421_ep->naks++ < NAK_MAX_FAST_RETRANSMITS) {
max3421_next_transfer(hcd, 1);
switch_sndfifo = 0;
+ } else
+ max3421_slow_retransmit(hcd);
break;
}
if (switch_sndfifo)
--
2.34.1
