Re: [PATCH] usb: devio: update max count of DPs per interval for ISOC

Greg Kroah-Hartman
2018-12-28T10:51:53Z

On Fri, Dec 28, 2018 at 06:27:44PM +0800, Chunfeng Yun wrote:
> The host shall be able to accept and send up to 96 DPs for
> devices operating at Gen 2 speed.

Why? What is this keeping from working properly today?

I need a much better changelog text here in order to be able to accept
this patch.

>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
> drivers/usb/core/devio.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index a75bc0b8a50f..82c16210e34c 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1564,12 +1564,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
> }
> for (totlen = u = 0; u < number_of_packets; u++) {
> /*
> - * arbitrary limit need for USB 3.0
> - * bMaxBurst (0~15 allowed, 1~16 packets)
> - * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> - * sizemax: 1024 * 16 * 3 = 49152
> + * arbitrary limit need for USB 3.1 Gen2
> + * sizemax: 96 DPs at SSP, 96 * 1024 = 98304
> */
> - if (isopkt[u].length > 49152) {
> + if (isopkt[u].length > 98304) {

Are we going to have to keep bumping this up as speeds get faster and
faster?

thanks,

greg k-h