On 18.09.2017 15:40, Bin Meng wrote:
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 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.@@ -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__);
Reviewed-by: Stefan Roese sr@denx.de Tested-by: Stefan Roese sr@denx.de
Thanks, Stefan