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.cn@gmail.com ---
common/usb.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/common/usb.c b/common/usb.c index 0904259..2aaf932 100644 --- a/common/usb.c +++ b/common/usb.c @@ -969,23 +969,24 @@ 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) @@ -1008,7 +1009,7 @@ 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("usb_setup_descriptor: invalid max packet size\n"); return -EIO; }