linux-kernel - Re: [PATCH] usb: dwc3: core: configure PHY before initializing host in dwc3_set

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Date:   Sat, 12 Nov 2022 23:15:47 +0100
From:   Ferry Toth <fntoth@...il.com>
To:     Sven Peter <sven@...npeter.dev>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Felipe Balbi <felipe.balbi@...ux.intel.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] usb: dwc3: core: configure PHY before initializing host
 in dwc3_set_mode

Hi Sven,

Op 12-11-2022 om 11:25 schreef Sven Peter:
> Usually, first the PHY is set to the correct mode and then the host or
> device side of the controller is initialized afterwards. Otherwise a PHY
> that's already used has to be reconfigured.
> dwc3_core_init_mode() does this correctly for both host and device and
> __dwc3_set_mode() does it correctly when switching to device mode.
> When setting up host mode however it first initializes xhci and only
> then changes the PHY's mode. Let's also do the operations in the correct
> order here.
> 
> Fixes: 958d1a4c40dd ("usb: dwc3: core: program PHY for proper DRD modes")
> Signed-off-by: Sven Peter <sven@...npeter.dev>
> ---
>   drivers/usb/dwc3/core.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index ad4d644e21a4..759d23d908fa 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -212,14 +212,15 @@ static void __dwc3_set_mode(struct work_struct *work)
>   
>   	switch (dwc->desired_dr_role) {
>   	case DWC3_GCTL_PRTCAP_HOST:
> +		if (dwc->usb2_phy)
> +			otg_set_vbus(dwc->usb2_phy->otg, true);
> +		phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);
> +		phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);
> +
>   		ret = dwc3_host_init(dwc);
>   		if (ret) {
>   			dev_err(dwc->dev, "failed to initialize host\n");
>   		} else {
> -			if (dwc->usb2_phy)
> -				otg_set_vbus(dwc->usb2_phy->otg, true);
> -			phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);
> -			phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);
>   			if (dwc->dis_split_quirk) {
>   				reg = dwc3_readl(dwc->regs, DWC3_GUCTL3);
>   				reg |= DWC3_GUCTL3_SPLITDISABLE;
This patch breaks usb host mode on Intel Merrifield platform. I am 
testing this on top of v6.0 +
* my 2 "usb: dwc3: core: defer probe on ulpi_read_id timeout" patches 
(otherwise tusb1210 will not be probed on this platform)
* Revert "usb: dwc3: disable USB core PHY management" (with/without this 
patch makes no difference)
* usb: dwc3: Do not get extcon device when usb-role-switch is used 
(with/without this patch makes no difference)

ftrace shows tusb1210 is indeed still probed, nevertheless in host mode 
it seems vbus is not powered as my connected smsc95xx based hub is not 
active (seems not plugged).

Flipping the switch to device mode gadgets work fine.

Could it be dwc3_host_init() needs to be called prior to otg_set_vbus()?