linux-kernel - Re: [PATCH] usb: xhci: Enable LPM for VIA LABS VL805

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Date:   Tue, 11 Feb 2020 10:49:51 +0100
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Mathias Nyman <mathias.nyman@...el.com>
Cc:     linux-usb@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: xhci: Enable LPM for VIA LABS VL805

Hi Mathias,

On 11.02.20 10:34, Mathias Nyman wrote:
> On 10.2.2020 20.59, Greg Kroah-Hartman wrote:
>> On Mon, Jan 20, 2020 at 03:24:22PM +0100, Nicolas Saenz Julienne wrote:
>>> This PCIe controller chip is used on the Raspberry Pi 4 and multiple
>>> adapter cards. There is no publicly available documentation for the
>>> chip, yet both the downstream RPi4 kernel and the controller cards
>>> support/advertise LPM support.
>>>
>>> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
>>> ---
>>>  drivers/usb/host/xhci-pci.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
>>> index 4917c5b033fa..c1976e98992b 100644
>>> --- a/drivers/usb/host/xhci-pci.c
>>> +++ b/drivers/usb/host/xhci-pci.c
>>> @@ -241,6 +241,9 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
>>>  			pdev->device == 0x3432)
>>>  		xhci->quirks |= XHCI_BROKEN_STREAMS;
>>>  
>>> +	if (pdev->vendor == PCI_VENDOR_ID_VIA && pdev->device == 0x3483)
>>> +		xhci->quirks |= XHCI_LPM_SUPPORT;
>>> +
>>>  	if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA &&
>>>  			pdev->device == 0x1042)
>>>  		xhci->quirks |= XHCI_BROKEN_STREAMS;
>> Mathias, is this in your review queue?
>>
> Ah yes, before adding link power management support for this controller we
> should check that it has sane (or any) exit latency values set in its
> HCSPARAMS3 capability register.
>
> Nicolas, if you have this controller could you show the capability registers:
>
> cat /sys/kernel/debug/usb/xhci/*/reg-cap
sorry for the naive question, but do you need the dump with or without
this patch applied?
>
> -Mathias
>
> _______________________________________________
> linux-rpi-kernel mailing list
> linux-rpi-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel

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