[PATCH 3/3] usb: aspeed-vhub: fix ep0 OUT ack received wrong length issue

-----Original Message-----
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Sent: Tuesday, November 30, 2021 7:49 AM
To: Neal Liu <neal_liu@aspeedtech.com>; Felipe Balbi <balbi@kernel.org>;
Greg Kroah-Hartman [off-list ref]; Joel Stanley
[off-list ref]; Andrew Jeffery [off-list ref]; Cai Huoqing
[off-list ref]; Tao Ren [off-list ref]; Julia Lawall
[off-list ref]; kernel test robot [off-list ref]; Sasha Levin
[off-list ref]; linux-usb at vger.kernel.org; linux-kernel at vger.kernel.org;
linux-arm-kernel at lists.infradead.org; linux-aspeed at lists.ozlabs.org
Cc: BMC-SW <redacted>
Subject: Re: [PATCH 3/3] usb: aspeed-vhub: fix ep0 OUT ack received wrong
length issue

On Fri, 2021-11-26 at 19:09 +0800, Neal Liu wrote:

quoted

diff --git a/drivers/usb/gadget/udc/aspeed-vhub/ep0.c

b/drivers/usb/gadget/udc/aspeed-vhub/ep0.c
index 74ea36c19b1e..bea9cbb191a2 100644

--- a/drivers/usb/gadget/udc/aspeed-vhub/ep0.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/ep0.c

@@ -251,6 +251,13 @@ static void ast_vhub_ep0_do_receive(struct

ast_vhub_ep *ep, struct ast_vhub_req
 		len = remain;
 		rc = -EOVERFLOW;
 	}
+
+	/* HW return wrong data len */
+	if (len < ep->ep.maxpacket && len != remain) {
+		EPDBG(ep, "using expected data len instead\n");
+		len = remain;
+	}
+

Wow, that is a nasty hw bug ! Patch looks good, I had to swap some of that
logic back into my brain but it looks like it won't break any normal case :-)

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Cheers,
Ben.

Thanks for your review.
-Neal