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Message-ID: <20251014231638.3tzfzjxg3x2kpeun@synopsys.com>
Date: Tue, 14 Oct 2025 23:16:40 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Sven Peter <sven@...nel.org>
CC: Janne Grunau <j@...nau.net>, Neal Gompa <neal@...pa.dev>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
"asahi@...ts.linux.dev" <asahi@...ts.linux.dev>,
"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] usb: dwc3: glue: Allow more fine grained control over
mode switches
On Mon, Oct 13, 2025, Sven Peter wrote:
> We need fine grained control over mode switched on the DWC3 controller
> present on Apple Silicon. Export core, host and gadget init and exit,
> ptrcap and susphy control functions. Also introduce an additional
> parameter to probe_data that allows to skip the final initialization
> step that would bring up host or gadget mode.
>
> Signed-off-by: Sven Peter <sven@...nel.org>
> ---
> drivers/usb/dwc3/core.c | 16 +++++--
> drivers/usb/dwc3/gadget.c | 2 +
> drivers/usb/dwc3/glue.h | 116 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/usb/dwc3/host.c | 2 +
> 4 files changed, 131 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index ae140c356295c03df3982ff4fa95f8638296e52d..526c0453b99aad79d99a842797e52d9290456d76 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -132,6 +132,7 @@ void dwc3_enable_susphy(struct dwc3 *dwc, bool enable)
> dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(i), reg);
> }
> }
> +EXPORT_SYMBOL_GPL(dwc3_enable_susphy);
>
> void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode, bool ignore_susphy)
> {
> @@ -158,6 +159,7 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode, bool ignore_susphy)
> dwc->current_dr_role = mode;
> trace_dwc3_set_prtcap(mode);
> }
> +EXPORT_SYMBOL_GPL(dwc3_set_prtcap);
>
> static void __dwc3_set_mode(struct work_struct *work)
> {
> @@ -975,7 +977,7 @@ static void dwc3_clk_disable(struct dwc3 *dwc)
> clk_disable_unprepare(dwc->bus_clk);
> }
>
> -static void dwc3_core_exit(struct dwc3 *dwc)
> +void dwc3_core_exit(struct dwc3 *dwc)
> {
> dwc3_event_buffers_cleanup(dwc);
> dwc3_phy_power_off(dwc);
> @@ -983,6 +985,7 @@ static void dwc3_core_exit(struct dwc3 *dwc)
> dwc3_clk_disable(dwc);
> reset_control_assert(dwc->reset);
> }
> +EXPORT_SYMBOL_GPL(dwc3_core_exit);
>
> static bool dwc3_core_is_valid(struct dwc3 *dwc)
> {
> @@ -1328,7 +1331,7 @@ static void dwc3_config_threshold(struct dwc3 *dwc)
> *
> * Returns 0 on success otherwise negative errno.
> */
> -static int dwc3_core_init(struct dwc3 *dwc)
> +int dwc3_core_init(struct dwc3 *dwc)
> {
> unsigned int hw_mode;
> u32 reg;
> @@ -1528,6 +1531,7 @@ static int dwc3_core_init(struct dwc3 *dwc)
>
> return ret;
> }
> +EXPORT_SYMBOL_GPL(dwc3_core_init);
>
> static int dwc3_core_get_phy(struct dwc3 *dwc)
> {
> @@ -2299,9 +2303,11 @@ int dwc3_core_probe(const struct dwc3_probe_data *data)
> dwc3_check_params(dwc);
> dwc3_debugfs_init(dwc);
>
> - ret = dwc3_core_init_mode(dwc);
> - if (ret)
> - goto err_exit_debugfs;
> + if (!data->skip_core_init_mode) {
> + ret = dwc3_core_init_mode(dwc);
> + if (ret)
> + goto err_exit_debugfs;
> + }
>
> pm_runtime_put(dev);
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 6f18b4840a25d176abb4134581ad0ce68ba19ffc..1f67fb6aead5725c2e7b553c635eab985c9e1d48 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4810,6 +4810,7 @@ int dwc3_gadget_init(struct dwc3 *dwc)
> err0:
> return ret;
> }
> +EXPORT_SYMBOL_GPL(dwc3_gadget_init);
>
> /* -------------------------------------------------------------------------- */
>
> @@ -4828,6 +4829,7 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
> dma_free_coherent(dwc->sysdev, sizeof(*dwc->ep0_trb) * 2,
> dwc->ep0_trb, dwc->ep0_trb_addr);
> }
> +EXPORT_SYMBOL_GPL(dwc3_gadget_exit);
>
> int dwc3_gadget_suspend(struct dwc3 *dwc)
> {
> diff --git a/drivers/usb/dwc3/glue.h b/drivers/usb/dwc3/glue.h
> index 7f326cff12458901904d4c32f62ed9357d0f6e3b..376e7aa74281c13bfb3a85dc033622bcff8d2acb 100644
> --- a/drivers/usb/dwc3/glue.h
> +++ b/drivers/usb/dwc3/glue.h
> @@ -15,11 +15,14 @@
> * @res: resource for the DWC3 core mmio region
> * @ignore_clocks_and_resets: clocks and resets defined for the device should
> * be ignored by the DWC3 core, as they are managed by the glue
> + * @skip_core_init_mode: Skip the finial initialization of the target mode, as
> + * it must be managed by the glue
> */
> struct dwc3_probe_data {
> struct dwc3 *dwc;
> struct resource *res;
> bool ignore_clocks_and_resets;
> + bool skip_core_init_mode;
> };
>
> /**
> @@ -60,4 +63,117 @@ int dwc3_pm_resume(struct dwc3 *dwc);
> void dwc3_pm_complete(struct dwc3 *dwc);
> int dwc3_pm_prepare(struct dwc3 *dwc);
>
> +
> +/* All of the following functions must only be used with skip_core_init_mode */
> +
> +/**
> + * dwc3_core_init - Initialize DWC3 core hardware
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Configures and initializes the core hardware, usually done by dwc3_core_probe.
> + * This function is provided for platforms that use skip_core_init_mode and need
> + * to finalize the core initialization after some platform-specific setup.
> + * It must only be called when using skip_core_init_mode and before
> + * dwc3_host_init or dwc3_gadget_init.
> + *
> + * Return: 0 on success, negative error code on failure
> + */
> +int dwc3_core_init(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_core_exit - Shut down DWC3 core hardware
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Disables and cleans up the core hardware state. This is usually handled
> + * internally by dwc3 and must only be called when using skip_core_init_mode
> + * and only after dwc3_core_init. Afterwards, dwc3_core_init may be called
> + * again.
> + */
> +void dwc3_core_exit(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_host_init - Initialize host mode operation
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Initializes the controller for USB host mode operation, usually done by
> + * dwc3_core_probe or from within the dwc3 USB role switch callback.
> + * This function is provided for platforms that use skip_core_init_mode and need
> + * to finalize the host initialization after some platform-specific setup.
> + * It must not be called before dwc3_core_init or when skip_core_init_mode is
> + * not used. It must also not be called when gadget or host mode has already
> + * been initialized.
> + *
> + * Return: 0 on success, negative error code on failure
> + */
> +int dwc3_host_init(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_host_exit - Shut down host mode operation
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Disables and cleans up host mode resources, usually done by
> + * the dwc3 USB role switch callback before switching controller mode.
> + * It must only be called when skip_core_init_mode is used and only after
> + * dwc3_host_init.
> + */
> +void dwc3_host_exit(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_gadget_init - Initialize gadget mode operation
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Initializes the controller for USB gadget mode operation, usually done by
> + * dwc3_core_probe or from within the dwc3 USB role switch callback. This
> + * function is provided for platforms that use skip_core_init_mode and need to
> + * finalize the gadget initialization after some platform-specific setup.
> + * It must not be called before dwc3_core_init or when skip_core_init_mode is
> + * not used. It must also not be called when gadget or host mode has already
> + * been initialized.
> + *
> + * Return: 0 on success, negative error code on failure
> + */
> +int dwc3_gadget_init(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_gadget_exit - Shut down gadget mode operation
> + * @dwc: Pointer to DWC3 controller context
> + *
> + * Disables and cleans up gadget mode resources, usually done by
> + * the dwc3 USB role switch callback before switching controller mode.
> + * It must only be called when skip_core_init_mode is used and only after
> + * dwc3_gadget_init.
> + */
> +void dwc3_gadget_exit(struct dwc3 *dwc);
> +
> +/**
> + * dwc3_enable_susphy - Control SUSPHY status for all USB ports
> + * @dwc: Pointer to DWC3 controller context
> + * @enable: True to enable SUSPHY, false to disable
> + *
> + * Enables or disables the USB3 PHY SUSPEND and USB2 PHY SUSPHY feature for
> + * all available ports.
> + * This is usually handled by the dwc3 core code and should only be used
> + * when skip_core_init_mode is used and the glue layer needs to manage SUSPHY
> + * settings itself, e.g., due to platform-specific requirements during mode
> + * switches.
> + */
> +void dwc3_enable_susphy(struct dwc3 *dwc, bool enable);
> +
> +/**
> + * dwc3_set_prtcap - Set the USB controller PRTCAP mode
> + * @dwc: Pointer to DWC3 controller context
> + * @mode: Target mode, must be one of DWC3_GCTL_PRTCAP_{HOST,DEVICE,OTG}
> + * @ignore_susphy: If true, skip disabling the SUSPHY and keep the current state
> + *
> + * Updates PRTCAP of the controller and current_dr_role inside the dwc3
> + * structure. For DRD controllers, this also disables SUSPHY unless explicitly
> + * told to skip via the ignore_susphy parameter.
> + *
> + * This is usually handled by the dwc3 core code and should only be used
> + * when skip_core_init_mode is used and the glue layer needs to manage mode
> + * transitions itself due to platform-specific requirements. It must be called
> + * with the correct mode before calling dwc3_host_init or dwc3_gadget_init.
> + */
> +void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode, bool ignore_susphy);
> +
> #endif
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index e77fd86d09cf0a36161c20ad3c83f10e67099775..cf6512ed17a69134e6ca1b884f76c1439693fab1 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -220,6 +220,7 @@ int dwc3_host_init(struct dwc3 *dwc)
> platform_device_put(xhci);
> return ret;
> }
> +EXPORT_SYMBOL_GPL(dwc3_host_init);
>
> void dwc3_host_exit(struct dwc3 *dwc)
> {
> @@ -230,3 +231,4 @@ void dwc3_host_exit(struct dwc3 *dwc)
> platform_device_unregister(dwc->xhci);
> dwc->xhci = NULL;
> }
> +EXPORT_SYMBOL_GPL(dwc3_host_exit);
>
> --
> 2.34.1
>
>
Thanks for the documentations!
Please rebase against Greg's usb-testing branch. I think there is
conflict.
Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Thanks,
Thinh
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