[U-Boot] [PATCH] usb: kbd: don't use int xfers when polling via ctrl xfers

[Marek Vasut]

On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren at nvidia.com>
> 
> When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a
> GET_REPORT control transfer to retrieve the initial state of the
> keyboard. This matches the technique used to poll the keyboard state.
> This is useful since it eliminates the remaining use of interrupt
> transfers from the USB keyboard driver, which allows it to work with
> USB HCD that don't support interrupt transfers.
> 
> Cc: Hans de Goede <hdegoede at redhat.com>
> Signed-off-by: Stephen Warren <swarren at nvidia.com>
> ---
> Are there any disadvantages to using control transfers over interrupt
> transfers? I'm not aware of any, but I assume there must be a reason
> that U-Boot typically uses interrupt transfers.

I initially implemented the control EP polling because I had a keyboard
which had issues with interrupt transfers.

Reviewed-by: Marek Vasut <marex at denx.de>

> ---
>  common/usb_kbd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/common/usb_kbd.c b/common/usb_kbd.c
> index 95912f99c767..81c4d62c632b 100644
> --- a/common/usb_kbd.c
> +++ b/common/usb_kbd.c
> @@ -475,6 +475,9 @@ static int usb_kbd_probe(struct usb_device *dev,
> unsigned int ifnum) USB_KBD_BOOT_REPORT_SIZE, data->new,
>  				      data->intinterval);
>  	if (!data->intq) {
> +#elif defined(CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP)
> +	if (usb_get_report(dev, iface->desc.bInterfaceNumber,
> +			   1, 0, data->new, USB_KBD_BOOT_REPORT_SIZE) < 0) {
>  #else
>  	if (usb_submit_int_msg(dev, data->intpipe, data->new, data->intpktsize,
>  			       data->intinterval) < 0) {

Best regards,
Marek Vasut