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From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: <gregkh@linuxfoundation.org>
Cc: <linux-usb@vger.kernel.org>, Al Cooper <alcooperx@gmail.com>,
	stable@vger.kernel.org,
	Mathias Nyman <mathias.nyman@linux.intel.com>
Subject: [PATCH 2/5] xhci: Fix enumeration issue when setting max packet size for FS devices.
Date: Wed, 24 Jun 2020 16:59:46 +0300	[thread overview]
Message-ID: <20200624135949.22611-3-mathias.nyman@linux.intel.com> (raw)
In-Reply-To: <20200624135949.22611-1-mathias.nyman@linux.intel.com>

From: Al Cooper <alcooperx@gmail.com>

Unable to complete the enumeration of a USB TV Tuner device.

Per XHCI spec (4.6.5), the EP state field of the input context shall
be cleared for a set address command. In the special case of an FS
device that has "MaxPacketSize0 = 8", the Linux XHCI driver does
not do this before evaluating the context. With an XHCI controller
that checks the EP state field for parameter context error this
causes a problem in cases such as the device getting reset again
after enumeration.

When that field is cleared, the problem does not occur.

This was found and fixed by Sasi Kumar.

Cc: stable@vger.kernel.org
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index bee5deccc83d..03b64b73eb99 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1430,6 +1430,7 @@ static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
 				xhci->devs[slot_id]->out_ctx, ep_index);
 
 		ep_ctx = xhci_get_ep_ctx(xhci, command->in_ctx, ep_index);
+		ep_ctx->ep_info &= cpu_to_le32(~EP_STATE_MASK);/* must clear */
 		ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK);
 		ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size));
 
-- 
2.17.1


  parent reply	other threads:[~2020-06-24 13:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24 13:59 [PATCH 0/5] xhci fixes for usb-linus Mathias Nyman
2020-06-24 13:59 ` [PATCH 1/5] xhci: Fix incorrect EP_STATE_MASK Mathias Nyman
2020-06-24 13:59 ` Mathias Nyman [this message]
2020-06-24 13:59 ` [PATCH 3/5] usb: host: xhci-mtk: avoid runtime suspend when removing hcd Mathias Nyman
2020-06-24 13:59 ` [PATCH 4/5] xhci: Return if xHCI doesn't support LPM Mathias Nyman
2020-06-24 13:59 ` [PATCH 5/5] xhci: Poll for U0 after disabling USB2 LPM Mathias Nyman

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