Hi John,
On 12/2/2021 9:17 PM, John Keeping wrote:
> DWC2 may be paired with a full-speed PHY which is not capable of
> high-speed operation. Report this correctly to the gadget core by
> setting max_speed from the core parameters.
>
> Prior to commit 5324bad66f09f ("usb: dwc2: gadget: implement
> udc_set_speed()") this didn't cause the hardware to be configured
> incorrectly, although the speed may have been reported incorrectly. But
> after that commit params.speed is updated based on a value passed in by
> the gadget core which may set it to a faster speed than is supported by
> the hardware. Initialising the max_speed parameter ensures the speed
> passed to dwc2_gadget_set_speed() will be one supported by the hardware.
>
> Fixes: 5324bad66f09f ("usb: dwc2: gadget: implement udc_set_speed()")
> Signed-off-by: John Keeping <john@xxxxxxxxxxxx>
> ---
> drivers/usb/dwc2/gadget.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index b884a83b26a6e..2bc03f41c70ad 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -4974,7 +4974,18 @@ int dwc2_gadget_init(struct dwc2_hsotg *hsotg)
> hsotg->params.g_np_tx_fifo_size);
> dev_dbg(dev, "RXFIFO size: %d\n", hsotg->params.g_rx_fifo_size);
>
> - hsotg->gadget.max_speed = USB_SPEED_HIGH;
> + switch (hsotg->params.speed) {
> + case DWC2_SPEED_PARAM_LOW:
> + hsotg->gadget.max_speed = USB_SPEED_LOW;
> + break;
> + case DWC2_SPEED_PARAM_FULL:
> + hsotg->gadget.max_speed = USB_SPEED_FULL;
> + break;
> + default:
> + hsotg->gadget.max_speed = USB_SPEED_HIGH;
> + break;
> + }
> +
> hsotg->gadget.ops = &dwc2_hsotg_gadget_ops;
> hsotg->gadget.name = dev_name(dev);
> hsotg->gadget.otg_caps = &hsotg->params.otg_caps;
>
Just setting gadget's max_speed doesn't resolve described issue. After
setting gadget's max_speed in your patch, it doesn't used in driver at
all. Per me, you need also fix dwc2_gadget_set_speed() function by
checking requested speed with max_speed: if requested speed higher than
max_speed then set speed to max_speed.
Thanks,
Minas
