linux-kernel - [RFC PATCH 1/1] usb: ehci: Remove erroneous return of EPROTO upon detection of stall

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Message-Id: <8248a5f80a8aa7cd391fa36a907d342fad38563b.1598887346.git.khalid@gonehiking.org>
Date:   Mon, 31 Aug 2020 10:08:43 -0600
From:   Khalid Aziz <khalid.aziz@...cle.com>
To:     stern@...land.harvard.edu, gregkh@...uxfoundation.org,
        erkka.talvitie@...cit.fi
Cc:     Khalid Aziz <khalid.aziz@...cle.com>, inux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Khalid Aziz <khalid@...ehiking.org>
Subject: [RFC PATCH 1/1] usb: ehci: Remove erroneous return of EPROTO upon detection of stall

With the USB 3.0/3.1 controller on MSI B450-A Pro Max motherboard,
full speed and low speed devices see constant resets making
keyboards and mouse unreliable and unusable. These resets are caused
by detection of stall in qtd_copy_status() and returning EPROTO
which in turn results in TT buffers in hub being cleared. Hubs do
not seem to repsond well to this and seem to hang which causes
further USB transactions to time out. A reset finally clears the
issue until we repeat the cycle all over again.

Signed-off-by: Khalid Aziz <khalid.aziz@...cle.com>
Cc: Khalid Aziz <khalid@...ehiking.org>
---
 drivers/usb/host/ehci-q.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 8a5c9b3ebe1e..7d4b2bc4633c 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -214,10 +214,6 @@ static int qtd_copy_status (
 		 * When MMF is active and PID Code is IN, queue is halted.
 		 * EHCI Specification, Table 4-13.
 		 */
-		} else if ((token & QTD_STS_MMF) &&
-					(QTD_PID(token) == PID_CODE_IN)) {
-			status = -EPROTO;
-		/* CERR nonzero + halt --> stall */
 		} else if (QTD_CERR(token)) {
 			status = -EPIPE;
 
-- 
2.25.1