Hi Lothar,
On Fri, Jun 30, 2017 at 2:15 PM, Lothar Waßmann LW@karo-electronics.de wrote:
Hi,
On Fri, 30 Jun 2017 11:49:56 +0800 Bin Meng wrote:
Hi,
On Fri, Jun 23, 2017 at 5:54 PM, Bin Meng bmeng.cn@gmail.com wrote:
The only work we need do in usb_setup_descriptor() is to initialize dev->descriptor.bMaxPacketSize0, when do_read is false. Other steps are the same as do_read being true.
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 | 40 ++++++++++++++++++---------------------- 1 file changed, 18 insertions(+), 22 deletions(-)
diff --git a/common/usb.c b/common/usb.c index 15e1e4c..293d968 100644 --- a/common/usb.c +++ b/common/usb.c @@ -962,37 +962,33 @@ static int usb_setup_descriptor(struct usb_device *dev, bool do_read) * some more, or keeps on retransmitting the 8 byte header. */
if (dev->speed == USB_SPEED_LOW) {dev->descriptor.bMaxPacketSize0 = 8;dev->maxpacketsize = PACKET_SIZE_8;} else {dev->descriptor.bMaxPacketSize0 = 64;dev->maxpacketsize = PACKET_SIZE_64;}dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;dev->epmaxpacketout[0] = dev->descriptor.bMaxPacketSize0;if (do_read) { 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) return err;} else {if (dev->speed == USB_SPEED_LOW)dev->descriptor.bMaxPacketSize0 = 8;elsedev->descriptor.bMaxPacketSize0 = 64; } dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;--
For some reason that I don't understand, this patch breaks EHCI. dev->maxpacketsize is equal to zero with this patch, which leads to a 'divide error' exception in ehci_submit_async(). Not sure if anyone has some hints?
In the do_read case the dev->descriptor.bMaxPacketSize0 is not set up.
In that case, dev->descriptor.bMaxPacketSize0 was read from device. Am I missing anything?
Regards, Bin