Re: [PATCH v4 2/4] usb gadget: Configure endpoint according to gadget speed.

From: Rajaram R
Date: Thu Jul 12 2012 - 07:23:17 EST


Hi


On Thu, Nov 18, 2010 at 6:17 PM, Tatyana Brokhman
<tlinder@xxxxxxxxxxxxxx> wrote:
>
> Add config_ep_by_speed() to configure the endpoint according to the gadget
> speed. Using this function will spare the FDs from handling the endpoint
> chosen descriptor.
>
> Signed-off-by: Tatyana Brokhman <tlinder@xxxxxxxxxxxxxx>
> ---
> drivers/usb/gadget/composite.c | 76 +++++++++++++++++++++++++++++++++++++++
> drivers/usb/gadget/epautoconf.c | 1 +
> include/linux/usb/composite.h | 21 +++++++++++
> include/linux/usb/gadget.h | 3 ++
> 4 files changed, 101 insertions(+), 0 deletions(-)
>
---cut---

> + */
> +int config_ep_by_speed(struct usb_gadget *g,
> + struct usb_function *f,
> + struct usb_ep *_ep)
> +{
> + struct usb_endpoint_descriptor *chosen_desc = NULL;
> + struct usb_descriptor_header **speed_desc = NULL;
> +
> + struct usb_descriptor_header **d_spd; /* cursor for speed desc */
> +
> + if (!g || !f || !_ep)
> + return -EIO;
> +
> + /* select desired speed */
> + switch (g->speed) {
> + case USB_SPEED_HIGH:
> + if (gadget_is_dualspeed(g)) {
> + speed_desc = f->hs_descriptors;
> + break;
> + }
> + /* else: fall through */
> + default:
> + speed_desc = f->descriptors;
> + }
> + /* find descriptors */
> + for (d_spd = next_ep_desc(speed_desc); d_spd;
> + d_spd = next_ep_desc(d_spd+1)) {
> + chosen_desc = (struct usb_endpoint_descriptor *)*d_spd;
> + if (chosen_desc->bEndpointAddress == _ep->bEndpointAddress)
> + goto ep_found;
> + }
> + return -EIO;
> +
> +ep_found:
> + /* commit results */
> + _ep->maxpacket = le16_to_cpu(chosen_desc->wMaxPacketSize);
> + _ep->desc = chosen_desc;

Could you please comment on why do we need to update gadget's ep list
with function's maxpacket ? Will this not affect when we switch
functions ?

> +
> + return 0;
> +}
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