[U-Boot] [RFC PATCH] usb: composite: Fix max packet size for USB3.0

[Marek Vasut]

On 12/12/2018 12:49 PM, Siva Durga Prasad Paladugu wrote:
> For USB3.0 the max packetsize for GET_DESCRIPTOR should be
> sent as exponent value for 2. This means for 512, max packet
> size should be filled with 9(2^9=512). Also, fill the USB
> version field with 3.0 if speed is negotiated to Superspeed.
> This fixes the issue of DFU gadget download failure with
> superspeed. With out this patch, the max packet size is
> overflowed to zero as the bMaxPacketsize is of u8 and hence
> host is not able to detect this device.
> 
> Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu at xilinx.com>

CCing Bin, I'd like his AB/RB.

> ---
>  drivers/usb/gadget/composite.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 5106cc5..c7e7623 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -735,8 +735,21 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
>  		case USB_DT_DEVICE:
>  			cdev->desc.bNumConfigurations =
>  				count_configs(cdev, USB_DT_DEVICE);
> -			cdev->desc.bMaxPacketSize0 =
> -				cdev->gadget->ep0->maxpacket;
> +
> +			/*
> +			 * If the speed is Super speed, then the supported
> +			 * max packet size is 512 and it should be sent as
> +			 * exponent of 2. So, 9(2^9=512) should be filled in
> +			 * bMaxPacketSize0. Also fill USB version as 3.0
> +			 * if speed is Super speed.
> +			 */
> +			if (cdev->gadget->speed == USB_SPEED_SUPER) {
> +				cdev->desc.bMaxPacketSize0 = 9;
> +				cdev->desc.bcdUSB = cpu_to_le16(0x0300);
> +			} else {
> +				cdev->desc.bMaxPacketSize0 =
> +					cdev->gadget->ep0->maxpacket;
> +			}
>  			value = min(w_length, (u16) sizeof cdev->desc);
>  			memcpy(req->buf, &cdev->desc, value);
>  			break;
> 


-- 
Best regards,
Marek Vasut