linux-kernel - [PATCH v2] USB: gadget: epautoconf: fix ep maxpacket check

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Date:	Mon, 30 Sep 2013 11:44:20 +0200
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, b.zolnierkie@...sung.com,
	m.szyprowski@...sung.com, andrzej.p@...sung.com,
	Robert Baldyga <r.baldyga@...sung.com>
Subject: [PATCH v2] USB: gadget: epautoconf: fix ep maxpacket check

Hello,
This is update for my patch fixing maxpacket check in epautoconfig. Now code
is better arranged for clearity and take into account super speed devices,
as Alan Stern suggested.

This patch fixes validation of maxpacket value given in endpoint descriptor.
Added check of maxpacket for bulk endpoints.

Correct maxpacket value is:

             FULL-SPEED  HIGH-SPEED  SUPER-SPEED
BULK         64          512         1024
INTERRUPT    64          1024        1024
ISOCHRONOUS  1023        1024        1024

Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>

Changelog:

v2:
- arrange code for clearity
- fix support for super speed devices

v1: https://lkml.org/lkml/2013/9/27/127
---
 drivers/usb/gadget/epautoconf.c |   54 +++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
index a777f7b..2daf3ba 100644
--- a/drivers/usb/gadget/epautoconf.c
+++ b/drivers/usb/gadget/epautoconf.c
@@ -136,25 +136,57 @@ ep_matches (
 	 * the usb spec fixes high speed bulk maxpacket at 512 bytes.
 	 */
 	max = 0x7ff & usb_endpoint_maxp(desc);
+
+	if (ep->maxpacket < max)
+		return 0;
+
 	switch (type) {
-	case USB_ENDPOINT_XFER_INT:
-		/* INT:  limit 64 bytes full speed, 1024 high/super speed */
+	case USB_ENDPOINT_XFER_BULK:
+		/*
+		 * LIMITS:
+		 * full speed:    64 bytes
+		 * high speed:   512 bytes
+		 * super speed: 1024 bytes
+		 */
+		if (max > 1024)
+			return 0;
+		if (!gadget_is_superspeed(gadget) && max > 512)
+			return 0;
 		if (!gadget_is_dualspeed(gadget) && max > 64)
 			return 0;
-		/* FALLTHROUGH */
+		break;
 
-	case USB_ENDPOINT_XFER_ISOC:
-		/* ISO:  limit 1023 bytes full speed, 1024 high/super speed */
-		if (ep->maxpacket < max)
+	case USB_ENDPOINT_XFER_INT:
+		/*
+		 * LIMITS:
+		 * full speed:		64 bytes
+		 * high/super speed:  1024 bytes
+		 * multiple transactions per microframe only for super speed
+		 */
+		 if (max > 1024)
 			return 0;
-		if (!gadget_is_dualspeed(gadget) && max > 1023)
+		 if (!gadget_is_superspeed(gadget)) {
+			if ((desc->wMaxPacketSize & cpu_to_le16(3<<11)))
+				return 0;
+		}
+		if (!gadget_is_dualspeed(gadget) && max > 64)
 			return 0;
+		break;
 
-		/* BOTH:  "high bandwidth" works only at high speed */
-		if ((desc->wMaxPacketSize & cpu_to_le16(3<<11))) {
-			if (!gadget_is_dualspeed(gadget))
+	case USB_ENDPOINT_XFER_ISOC:
+		/*
+		 * LIMITS:
+		 * full speed:	     1023 bytes
+		 * high/super speed: 1024 bytes
+		 * multiple transactions per microframe for high/super speed
+		 */
+		if (max > 1024)
+			return 0;
+		if (!gadget_is_dualspeed(gadget)) {
+			if (max > 1023)
+				return 0;
+			if ((desc->wMaxPacketSize & cpu_to_le16(3<<11)))
 				return 0;
-			/* configure your hardware with enough buffering!! */
 		}
 		break;
 	}
-- 
1.7.9.5

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