Re: [PATCH RFC 05/22] usb: dwc3: apple: Do not use host-vbus-glitches workaround

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Thu, Aug 21, 2025, Sven Peter wrote:
> From: Janne Grunau <j@jannau.net>
> 
> It results in SErrors during init presumedly because MMIO accesses fail
> while certain parts are shutdown.
> 
> Signed-off-by: Janne Grunau <j@jannau.net>
> Signed-off-by: Sven Peter <sven@kernel.org>
> ---
>  drivers/usb/dwc3/core.c | 1 +
>  drivers/usb/dwc3/core.h | 2 ++
>  drivers/usb/dwc3/host.c | 5 ++++-
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 26aa507a738f001409a97ef563c6561433a1cac5..8d2dc7fa18114102cc8893c4ca0e745e16f30754 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2273,6 +2273,7 @@ int dwc3_core_probe(const struct dwc3_probe_data *data)
>  
>  			dwc->dr_mode = USB_DR_MODE_OTG;
>  			dwc->role_switch_reset_quirk = true;
> +			dwc->no_early_roothub_poweroff = true;
>  		}
>  	}
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 38f32f2a6193c1b2662ab4f38f4d20cf4b0e198d..3c3a36ec37345b2f9e71444ba3b90b52dbd24443 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1155,6 +1155,7 @@ struct dwc3_scratchpad_array {
>   * @susphy_state: state of DWC3_GUSB2PHYCFG_SUSPHY + DWC3_GUSB3PIPECTL_SUSPHY
>   *		  before PM suspend.
>   * @role_switch_reset_quirk: set to force reinitialization after any role switch
> + * @no_early_roothub_poweroff: set to skip early root hub port power off
>   * @imod_interval: set the interrupt moderation interval in 250ns
>   *			increments or 0 to disable.
>   * @max_cfg_eps: current max number of IN eps used across all USB configs.
> @@ -1394,6 +1395,7 @@ struct dwc3 {
>  	unsigned		susphy_state:1;
>  
>  	unsigned		role_switch_reset_quirk:1;
> +	unsigned		no_early_roothub_poweroff:1;
>  
>  	u16			imod_interval;
>  
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index f7a71e6f9d80aca632f1f970d900a3de8a76f0a7..f7c3a0fc5fe258705311f89c1ba11ff599c01afe 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -134,8 +134,11 @@ int dwc3_host_init(struct dwc3 *dwc)
>  	/*
>  	 * Some platforms need to power off all Root hub ports immediately after DWC3 set to host
>  	 * mode to avoid VBUS glitch happen when xhci get reset later.
> +	 * On Apple platforms we must not touch any MMIO yet because dwc3
> +	 * will not work correctly before its PHY has been initialized.

This doesn't make sense, the phy should've been initialized by this
point. We already access MMIO before this. Even your [PATCH RFC 7/22]
attempts to access MMIO before this, yet accessing here causes problem.
Do we know when the phy get initialized then?

BR,
Thinh

>  	 */
> -	dwc3_power_off_all_roothub_ports(dwc);
> +	if (!dwc->no_early_roothub_poweroff)
> +		dwc3_power_off_all_roothub_ports(dwc);
>  
>  	irq = dwc3_host_get_irq(dwc);
>  	if (irq < 0)
> 
> -- 
> 2.34.1
> 
>