Re: [PATCH v2 2/3] usb: chipidea: udc: limit usb request length to max 16KB

Peter Chen
2024-09-25T12:47:13Z

On 24-09-23 16:12:02, Xu Yang wrote:
> To let the device controller work properly on short packet limitations,
> one usb request should only correspond to one dTD. Then every dTD will
> set IOC. In theory, each dTD support up to 20KB data transfer if the
> offset is 0. Due to we cannot predetermine the offset, this will limit
> the usb request length to max 16KB. This should be fine since most of
> the user transfer data based on this size policy.
>
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

Acked-by: Peter Chen <peter.chen@kernel.org>
>
> ---
> Changes in v2:
> - limit request length only when ci->has_short_pkt_limit set
> - modify commit message
> ---
> drivers/usb/chipidea/ci.h | 1 +
> drivers/usb/chipidea/udc.c | 6 ++++++
> 2 files changed, 7 insertions(+)
>
> diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
> index e4b003d060c2..97437de52ef6 100644
> --- a/drivers/usb/chipidea/ci.h
> +++ b/drivers/usb/chipidea/ci.h
> @@ -25,6 +25,7 @@
> #define TD_PAGE_COUNT 5
> #define CI_HDRC_PAGE_SIZE 4096ul /* page size for TD's */
> #define ENDPT_MAX 32
> +#define CI_MAX_REQ_SIZE (4 * CI_HDRC_PAGE_SIZE)
> #define CI_MAX_BUF_SIZE (TD_PAGE_COUNT * CI_HDRC_PAGE_SIZE)
>
> /******************************************************************************
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 18c1882cf088..5badb39cb2bf 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -972,6 +972,12 @@ static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
> return -EMSGSIZE;
> }
>
> + if (ci->has_short_pkt_limit &&
> + hwreq->req.length > CI_MAX_REQ_SIZE) {
> + dev_err(hwep->ci->dev, "request length too big (max 16KB)\n");
> + return -EMSGSIZE;
> + }
> +
> /* first nuke then test link, e.g. previous status has not sent */
> if (!list_empty(&hwreq->queue)) {
> dev_err(hwep->ci->dev, "request already in queue\n");
> --
> 2.34.1
>