RE: [PATCH v2 2/4] usb: uhci: Add reset control support

Ryan Chen
2025-09-18T02:27:39Z

> Subject: Re: [PATCH v2 2/4] usb: uhci: Add reset control support
>
> On Wed, Sep 17, 2025 at 10:19:24AM +0800, Ryan Chen wrote:
> > Some SoCs, such as the Aspeed AST2700, require the UHCI controller to
> > be taken out of reset before it can operate. Add optional reset
> > control support to the UHCI platform driver.
> >
> > The driver now acquires an optional reset line from device tree,
> > deasserts it during probe, and asserts it again in the error path and
> > shutdown.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> > ---
> > drivers/usb/host/uhci-hcd.h | 1 +
> > drivers/usb/host/uhci-platform.c | 17 +++++++++++++++--
> > 2 files changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
> > index 13ee2a6144b2..4326d1f3ca76 100644
> > --- a/drivers/usb/host/uhci-hcd.h
> > +++ b/drivers/usb/host/uhci-hcd.h
> > @@ -445,6 +445,7 @@ struct uhci_hcd {
> > short load[MAX_PHASE]; /* Periodic allocations */
> >
> > struct clk *clk; /* (optional) clock source */
> > + struct reset_control *rsts; /* (optional) clock reset */
>
> This new field is used only in uhci_hcd_platform_probe(). Therefore it does
> not need to be stored in the uhci_hcd structure; it can simply be a local
> variable.
>
> Alan Stern

Sorry, I think I miss add reset_control_assert in uhci_hcd_platform_remove function.
So, It is needed in uhci_hcd structure, I will submit in next.
Thanks your review.
>
> >
> > /* Reset host controller */
> > void (*reset_hc) (struct uhci_hcd *uhci);
> > diff --git a/drivers/usb/host/uhci-platform.c
> > b/drivers/usb/host/uhci-platform.c
> > index 62318291f566..1c1715bddc27 100644
> > --- a/drivers/usb/host/uhci-platform.c
> > +++ b/drivers/usb/host/uhci-platform.c
> > @@ -11,6 +11,7 @@
> > #include <linux/of.h>
> > #include <linux/device.h>
> > #include <linux/platform_device.h>
> > +#include <linux/reset.h>
> >
> > static int uhci_platform_init(struct usb_hcd *hcd) { @@ -132,17
> > +133,29 @@ static int uhci_hcd_platform_probe(struct platform_device
> *pdev)
> > goto err_rmr;
> > }
> >
> > + uhci->rsts = devm_reset_control_array_get_optional_shared(&pdev->dev);
> > + if (IS_ERR(uhci->rsts)) {
> > + ret = PTR_ERR(uhci->rsts);
> > + goto err_clk;
> > + }
> > + ret = reset_control_deassert(uhci->rsts);
> > + if (ret)
> > + goto err_clk;
> > +
> > ret = platform_get_irq(pdev, 0);
> > if (ret < 0)
> > - goto err_clk;
> > + goto err_reset;
> >
> > ret = usb_add_hcd(hcd, ret, IRQF_SHARED);
> > if (ret)
> > - goto err_clk;
> > + goto err_reset;
> >
> > device_wakeup_enable(hcd->self.controller);
> > return 0;
> >
> > +err_reset:
> > + if (!IS_ERR_OR_NULL(uhci->rsts))
> > + reset_control_assert(uhci->rsts);
> > err_clk:
> > clk_disable_unprepare(uhci->clk);
> > err_rmr:
> > --
> > 2.34.1
> >