linux-kernel - Re: [PATCH v2 5/9] usb: xhci-pci: Add support for reset controllers

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Message-ID: <d452ddb8-cd30-1bfc-7b72-af3412e22ed4@gmail.com>
Date:   Tue, 9 Jun 2020 11:13:29 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        f.fainelli@...il.com, gregkh@...uxfoundation.org, wahrenst@....net,
        p.zabel@...gutronix.de, linux-kernel@...r.kernel.org,
        Mathias Nyman <mathias.nyman@...el.com>
Cc:     linux-usb@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com, tim.gover@...pberrypi.org,
        linux-pci@...r.kernel.org, helgaas@...nel.org,
        andy.shevchenko@...il.com, mathias.nyman@...ux.intel.com,
        lorenzo.pieralisi@....com
Subject: Re: [PATCH v2 5/9] usb: xhci-pci: Add support for reset controllers



On 6/9/2020 10:49 AM, Nicolas Saenz Julienne wrote:
> Some atypical users of xhci-pci might need to manually reset their xHCI
> controller before starting the HCD setup. Check if a reset controller
> device is available to the PCI bus and trigger a reset.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> 
> ---
> 
> Changes since v1:
>  - Use proper reset API
>  - Make code simpler
> 
>  drivers/usb/host/xhci-pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index ef513c2fb843..6e96affa4ceb 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -12,6 +12,7 @@
>  #include <linux/slab.h>
>  #include <linux/module.h>
>  #include <linux/acpi.h>
> +#include <linux/reset.h>
>  
>  #include "xhci.h"
>  #include "xhci-trace.h"
> @@ -339,6 +340,7 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  	struct xhci_hcd *xhci;
>  	struct usb_hcd *hcd;
>  	struct xhci_driver_data *driver_data;
> +	struct reset_control *reset;
>  
>  	driver_data = (struct xhci_driver_data *)id->driver_data;
>  	if (driver_data && driver_data->quirks & XHCI_RENESAS_FW_QUIRK) {
> @@ -347,6 +349,11 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  			return retval;
>  	}
>  
> +	reset = devm_reset_control_get_optional_exclusive(&dev->bus->dev, NULL);
> +	if (IS_ERR(reset))
> +		return PTR_ERR(reset);
> +	reset_control_reset(reset);

Sorry for not catching this earlier, since this is a generic integration
with the reset controller API, should not you also add a
reset_control_reset() to hcd_pci_resume() for symmetry?

> +
>  	/* Prevent runtime suspending between USB-2 and USB-3 initialization */
>  	pm_runtime_get_noresume(&dev->dev);
>  
> 

-- 
Florian