linux-kernel - Re: [PATCH v5] usb: host: xhci-plat: Set XHCI_SKIP_PHY

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Date:   Fri, 7 Jan 2022 10:27:59 +0530
From:   Sandeep Maheswaram <quic_c_sanm@...cinc.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        "Doug Anderson" <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>
Subject: Re: [PATCH v5] usb: host: xhci-plat: Set XHCI_SKIP_PHY_INIT quirk for
 DWC3 controller


On 1/6/2022 7:55 PM, Greg Kroah-Hartman wrote:
> On Wed, Dec 22, 2021 at 11:39:43AM +0530, Sandeep Maheswaram wrote:
>> Set XHCI_SKIP_PHY_INIT quirk to avoid phy initialization twice.
>> Runtime suspend of phy drivers was failing from DWC3 driver as runtime
>> usage value is 2 because the phy is initialized from DWC3 and HCD core.
>> DWC3 manages phy in their core drivers. Set this quirk to avoid phy
>> initialization in HCD core.
>>
>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>> ---
>> v5:
>> Added comment to explain the change done.
>> v4:
>> Changed pdev->dev.parent->of_node to sysdev->of_node
>>
>>   drivers/usb/host/xhci-plat.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
>> index c1edcc9..e6014d4 100644
>> --- a/drivers/usb/host/xhci-plat.c
>> +++ b/drivers/usb/host/xhci-plat.c
>> @@ -327,6 +327,14 @@ static int xhci_plat_probe(struct platform_device *pdev)
>>   					 &xhci->imod_interval);
>>   	}
>>   
>> +	/*
>> +	 * Set XHCI_SKIP_PHY_INIT quirk to avoid phy initialization twice.
>> +	 * DWC3 manages phy in their core drivers. Set this quirk to avoid phy
>> +	 * initialization in HCD core.
>> +	 */
>> +	if (of_device_is_compatible(sysdev->of_node, "snps,dwc3"))
>> +		xhci->quirks |= XHCI_SKIP_PHY_INIT;
>> +
> Why is this function caring about dwc3 stuff?  Shoudn't this be a
> "generic" device property instead of this device-specific one?
>
> thanks,
>
> greg k-h

This quirk is set only if required for some controllers (eg: dwc3 & cdns3).

Please check below commit.

https://lore.kernel.org/all/20200918131752.16488-5-mathias.nyman@linux.intel.com/


Regards

Sandeep