Full speed device endpoint 0 can have 8/16/32/64 bMaxPacketSize0.
Other speed devices report fixed value per USB spec. So it only
makes sense if we send a get device descriptor with 64 bytes to
full speed devices.
While we are here, update the comment block to be within 80 cols.
Signed-off-by: Bin Meng <bmeng...@gmail.com>
---
common/usb.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/common/usb.c b/common/usb.c
index 6cb92ef..88cee81 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -970,23 +970,24 @@ static int usb_setup_descriptor(struct usb_device *dev,
bool do_read)
dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;
dev->epmaxpacketout[0] = dev->descriptor.bMaxPacketSize0;
- if (do_read) {
+ if (do_read && dev->speed == USB_SPEED_FULL) {
int err;
/*
- * Validate we've received only at least 8 bytes, not that we've
- * received the entire descriptor. The reasoning is:
- * - The code only uses fields in the first 8 bytes, so that's
all we
- * need to have fetched at this stage.
- * - The smallest maxpacket size is 8 bytes. Before we know the
actual
- * maxpacket the device uses, the USB controller may only
accept a
- * single packet. Consequently we are only guaranteed to
receive 1
- * packet (at least 8 bytes) even in a non-error case.
+ * Validate we've received only at least 8 bytes, not that
+ * we've received the entire descriptor. The reasoning is:
+ * - The code only uses fields in the first 8 bytes, so
+ * that's all we need to have fetched at this stage.
+ * - The smallest maxpacket size is 8 bytes. Before we know
+ * the actual maxpacket the device uses, the USB controller
+ * may only accept a single packet. Consequently we are only
+ * guaranteed to receive 1 packet (at least 8 bytes) even in
+ * a non-error case.
*
- * At least the DWC2 controller needs to be programmed with the
number
- * of packets in addition to the number of bytes. A request for
64
- * bytes of data with the maxpacket guessed as 64 (above)
yields a
- * request for 1 packet.
+ * At least the DWC2 controller needs to be programmed with
+ * the number of packets in addition to the number of bytes.
+ * A request for 64 bytes of data with the maxpacket guessed
+ * as 64 (above) yields a request for 1 packet.
*/
err = get_descriptor_len(dev, 64, 8);
if (err)
@@ -1009,7 +1010,7 @@ static int usb_setup_descriptor(struct usb_device *dev,
bool do_read)
dev->maxpacketsize = PACKET_SIZE_64;
break;
default:
- printf("usb_new_device: invalid max packet size\n");
+ printf("%s: invalid max packet size\n", __func__);
return -EIO;
}
--
2.9.2
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