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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: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20250910160730.585303-1-herve.codina@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Herve Codina 2025-09-10 18:07:30 +02:00 committed by Greg Kroah-Hartman
parent a5d2edb2c9
commit e77ee1d2a8
1 changed files with 26 additions and 0 deletions
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26
drivers/usb/dwc2/params.c
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@ -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;