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Subject: Re: [PATCH v1] usb: xhci: add LPM quirk for ensuring uPD720201 into
 D3 state after S5
To:     Mathias Nyman <mathias.nyman@linux.intel.com>,
        Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        zhuyinbo@loongson.cn, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <1635751025-25906-1-git-send-email-zhuyinbo@loongson.cn>
 <f7cfa6bc-a0f6-aaa6-aafa-b4fe2714ca40@linux.intel.com>
From:   zhuyinbo <zhuyinbo@loongson.cn>
Message-ID: <59c395bf-daac-9835-7063-5f8b6a9f3338@loongson.cn>
Date:   Wed, 3 Nov 2021 16:34:45 +0800
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在 2021/11/1 下午5:18, Mathias Nyman 写道:
> Hi
>
> On 1.11.2021 9.17, Yinbo Zhu wrote:
>> After S5, any pci device should into D3 state that if supported, but the
>> uPD720201 was not and it may be the cause of xhci firmware and cause
>> OSPM power consumption is more higher that S5 than S4. I think xhci HCD
>> can add a quirk ensure it into D3 state after S5 that is appropriate
>> and this patch was to add LPM quirk and set PCI_D3hot to uPD720201 pmsc
>> register in xhci_pci_shutdown to fix xhci power consumption issue.
>>
>> Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
> I think we need a better understanding of the underlying issue before
> adding a quirk like this.
>
> Is this a known issue with the uPD720201 controller firmware? or is it
> an issue with ACPI table entries not supporting the proper D state in BIOS
> on the tested platform, or something completely different?

Yes, and I notice other xhci hc doesn't encounter this power consumption 
issue I think that xhci firmware

may be set D3 after s5, but the xhci firmware code isn't visible,  in 
addition I find that test platform the

_PS3 method wasn't implemented in acpi table which can make device into 
S3, Bios team didn't add it for

some platform reason and I think xhci hcd to ensure device into D3 state 
after s5 that is appropriate

>
> Also, LPM usually refers to "Link Power Management" in the xHCI spec.
> This is about the U1 and U2 link states for the connected USB device.
>
> If we end up needing a new xhci quirk it will need a new name.
>
> Thanks
> -Mathias

Hi Mathias,


I had changed the quirk that replace XHCI_LPM_QUIRK with XHCI_LWP_QUIRK 
as v2 version patch.

please view the v2 version patch.


Thanks,

Yinbo.