linux-kernel - Re: [PATCH] xhci: EHCI/xHCI ports switching on Intense-PC.

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Date:	Wed, 18 Jul 2012 09:57:30 +0300
From:	Denis Turischev <denis@...pulab.co.il>
To:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
CC:	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] xhci: EHCI/xHCI ports switching on Intense-PC.

On 07/17/2012 07:54 AM, Sarah Sharp wrote:
> On Mon, Jul 16, 2012 at 07:46:06PM +0300, Denis Turischev wrote:
>> Intense-PC is Compulab's mini-desktop with Intel Panther Point
>> chipset.
>>
>> Unconditional ports switching provided by function
>> usb_enable_xhci_ports() leads to surprising results, after shutdown
>> system powered-on again after a few seconds. On Windows power
>> related problems were not observed.
> 
> Do you have wake on lan enabled in the BIOS?  I have heard reports from
> other users that this is a BIOS bug triggered by WOL.

Bug appears with WOL disabled too, moreover, it appears with PCH LAN
disabled at all in the BIOS.

> 
>> The patch avoids ports switching for Intense-PC.
>>
>> Signed-off-by: Denis Turischev <denis@...pulab.co.il>
>> ---
>>  drivers/usb/host/pci-quirks.c |    7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
>> index df0828c..6f72593 100644
>> --- a/drivers/usb/host/pci-quirks.c
>> +++ b/drivers/usb/host/pci-quirks.c
>> @@ -759,6 +759,13 @@ void usb_enable_xhci_ports(struct pci_dev *xhci_pdev)
>>  {
>>  	u32		ports_available;
>>
>> +	const char *brd_name;
>> +	brd_name = dmi_get_system_info(DMI_BOARD_NAME);
>> +
>> +	/* quirk for Compulab's Intense-PC board */
>> +	if (brd_name && strstr(brd_name, "Intense-PC"))
>> +		return;
>> +
> 
> No, this fix is not acceptable.  You won't get USB 3.0 speeds if the
> ports are not switched over.  Now, we can add a quirk to the xHCI
> shutdown function to switch the ports back to EHCI on shutdown.  That
> might not trigger the BIOS bug.

Yes, switching back to EHCI in xhci_shutdown() solves the problem.

I suppose to do something like this in xhci_shutdown:
	pdev = to_pci_dev(hcd->self.controller);

	if (usb_is_intel_switchable_xhci(pdev)){
		brd_name = dmi_get_system_info(DMI_BOARD_NAME);

		/* quirk for Compulab's Intense-PC board */
		if (brd_name && strstr(brd_name, "Intense-PC"))
			usb_disable_xhci_ports(pdev);
	}

Is it ok?

May be it worth to disable xhci ports for all intel switchable
devices, not only for Intense-PC?

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