Commit ff826648 authored by Mark Tomlinson's avatar Mark Tomlinson Committed by Greg Kroah-Hartman
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USB: MAX3421: Handle USB NAK correctly 



A USB peripheral can respond with a NAK if it is not yet ready to
send/receive data. In this case, the transaction should be retried. The
MAX3421 driver did do this, and switched to a different type of retry
after a number of 'fast' retries. On at least some USB flash devices,
this second type of retry never succeeds. This patch changes the
behaviour so that 'fast' retries continue.

Signed-off-by: default avatarMark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20230127024734.8777-1-mark.tomlinson@alliedtelesis.co.nz


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7194e5e0

drivers/usb/host/max3421-hcd.c

+2 −11
Original line number Diff line number Diff line
@@ -72,12 +72,6 @@ 
#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

 * resposne 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: */
@@ -924,11 +918,8 @@ max3421_handle_error(struct usb_hcd *hcd, u8 hrsl) 
		 * 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)