linux-kernel - Re: [PATCH v1 5/8] usb: chipidea: tegra: Support host mode

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Message-ID: <e4a63b73-5fc9-33da-abd5-771b2f3813f6@gmail.com>
Date:   Wed, 16 Dec 2020 18:56:30 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Peter Chen <peter.chen@....com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Felipe Balbi <balbi@...nel.org>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Peter Geis <pgwipeout@...il.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 5/8] usb: chipidea: tegra: Support host mode

16.12.2020 12:32, Peter Chen пишет:
>> ...
>>>> +static int tegra_usb_internal_port_reset(struct ehci_hcd *ehci,
>>>> +					 u32 __iomem *portsc_reg,
>>>> +					 unsigned long *flags)
>>>> +{
>>>> +	u32 saved_usbintr, temp;
>>>> +	unsigned int i, tries;
>>>> +	int retval = 0;
>>>> +
>>>> +	saved_usbintr = ehci_readl(ehci, &ehci->regs->intr_enable);
>>>> +	/* disable USB interrupt */
>>>> +	ehci_writel(ehci, 0, &ehci->regs->intr_enable);
>>>> +	spin_unlock_irqrestore(&ehci->lock, *flags);
>>>> +
>>>> +	/*
>>>> +	 * Here we have to do Port Reset at most twice for
>>>> +	 * Port Enable bit to be set.
>>>> +	 */
>>>> +	for (i = 0; i < 2; i++) {
>>>> +		temp = ehci_readl(ehci, portsc_reg);
>>>> +		temp |= PORT_RESET;
>>>> +		ehci_writel(ehci, temp, portsc_reg);
>>>> +		mdelay(10);
>>> Needs accurate delay? How about usleep_range?
>> To be hones I don't know for sure whether hub_control() could be used from
>> interrupt context.  This mdelay is borrowed from the older ehci-tegra driver.
>>
>> Are you suggesting that it should be safe to sleep here?
>>
> I see msleep is called at tegra_ehci_hub_control at ehci-tegra.c.
> .hub_control is not called at interrupt context.
> 

Alright, I'll change to use msleep() in v2, thanks.