Commit e77ee1d2 authored by Herve Codina's avatar Herve Codina Committed by Greg Kroah-Hartman
Browse files

usb: dwc2: Add support for 'maximum-speed' property 



The DWC2 IP can be properly integrated in a SoC to work at high-speed
USB speed but some board issues, EMC constraints or any other reasons
can lead to the need to limit this USB speed at board level.

The device-tree 'maximum-speed' property already exists for this purpose
but is not handled by the DWC2 driver.

Fill this lack adding support for 'maximum-speed' property and so allow
to limit the USB speed in device-tree (board description).

Signed-off-by: default avatarHerve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20250910160730.585303-1-herve.codina@bootlin.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a5d2edb2

drivers/usb/dwc2/params.c

+26 −0
Original line number Diff line number Diff line
@@ -1029,11 +1029,33 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg) 
	return 0;

}



static int dwc2_limit_speed(struct dwc2_hsotg *hsotg)

{

	enum usb_device_speed usb_speed;



	usb_speed = usb_get_maximum_speed(hsotg->dev);

	switch (usb_speed) {

	case USB_SPEED_LOW:

		dev_err(hsotg->dev, "Maximum speed cannot be forced to low-speed\n");

		return -EINVAL;

	case USB_SPEED_FULL:

		if (hsotg->params.speed == DWC2_SPEED_PARAM_LOW)

			break;

		hsotg->params.speed = DWC2_SPEED_PARAM_FULL;

		break;

	default:

		break;

	}



	return 0;

}



typedef void (*set_params_cb)(struct dwc2_hsotg *data);



int dwc2_init_params(struct dwc2_hsotg *hsotg)

{

	set_params_cb set_params;

	int ret;



	dwc2_set_default_params(hsotg);

	dwc2_get_device_properties(hsotg);
@@ -1051,6 +1073,10 @@ int dwc2_init_params(struct dwc2_hsotg *hsotg) 
		}

	}



	ret = dwc2_limit_speed(hsotg);

	if (ret)

		return ret;



	dwc2_check_params(hsotg);



	return 0;