Re: [PATCH v4 2/2] usb: dwc3: dwc3-generic-plat: Add Renesas R-Car Gen5 DWC3 xHCI USB controller glue

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The R-Car Gen5 DWC3 glue registers are configured during `probe` but are not restored during system or runtime resume.
--

--- Patch [2]: [PATCH v4 2/2] usb: dwc3: dwc3-generic-plat: Add Renesas R-Car Gen5 DWC3 xHCI USB controller glue ---
commit e26d897ddeb77c9fa5aded8c04ec1d73b9445010
Author: Thanh Quan <thanh.quan.xn@renesas.com>

usb: dwc3: dwc3-generic-plat: Add Renesas R-Car Gen5 DWC3 xHCI USB controller glue

This commit adds glue logic support for the Renesas R-Car Gen5 DWC3 USB
controller to the generic DWC3 platform driver.

> diff --git a/drivers/usb/dwc3/dwc3-generic-plat.c b/drivers/usb/dwc3/dwc3-generic-plat.c
> index ca69ac0eb07ce..dec89b068291a 100644
> --- a/drivers/usb/dwc3/dwc3-generic-plat.c
> +++ b/drivers/usb/dwc3/dwc3-generic-plat.c

[ ... ]

> +static int dwc3_renesas_rcar_gen5_init(struct dwc3_generic *dwc3g)
> +{

[ ... ]

> +	/*
> +	 * The datasheet describes initialization procedure without full
> +	 * information about the registers. Therefore, the source code is
> +	 * based on the bare metal code shared by the board team.
> +	 */
> +	writew(0x211, glue + 0x26);
> +
> +	/* USB2 does need additional register programming. */
> +	if (!usb2only)
> +		return 0;
> +
> +	writew(0x11, glue + 0x81c);
> +	writew(0x0, glue + 0x81a);
> +	writew(0x1, glue + 0x802);
> +
> +	usleep_range(10000, 20000);
> +
> +	writew(0x0, glue + 0x802);
> +	writew(0x1, glue + 0x2a);
> +	writew(0x1, glue + 0x81a);
> +
> +	usleep_range(10000, 20000);
> +
> +	return 0;
> +}

[Severity: High]
Will this glue register configuration be lost during system suspend or runtime
autosuspend?

If the device is powered down during system suspend or runtime suspend (which
triggers naturally after 5 seconds of inactivity), these custom registers will
lose their state.

When waking up, dwc3_generic_resume() or dwc3_generic_runtime_resume() is
executed, but neither invokes a platform-specific hook to reapply the glue
configuration. Will the controller malfunction upon resume without restoring
this configuration?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260819050109.681890-1-marek.vasut+renesas@mailbox.org?part=2