Messages in this thread | | | Subject | Re: [PATCH v2] USB: Disable USB2 LPM at shutdown | From | Kai-Heng Feng <> | Date | Mon, 5 Aug 2019 20:58:33 +0800 |
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Hi Greg,
at 17:22, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> at 22:17, Alan Stern <stern@rowland.harvard.edu> wrote: >> >> I agree with Kai-Heng, this seems like a fairly light-weight solution >> to a reasonable problem. > > Thanks for your review. > >> As to the issue of how much it will slow down system shutdowns, I have >> no idea. Probably not very much, unless somebody has an unusually >> large number of USB devices plugged in, but only testing can give a >> real answer. > > In addition to that, only USB2 devices that enable LPM will slow down > shutdown process. > Right now only internally connected USB2 devices enable LPM, so the > numbers are even lower. > >> I suppose we could add an HCD flag for host controllers which require >> this workaround. Either way, it's probably not a very big deal. > > IMO this is not necessary. Only xHCI that reports hw_lpm_support will be > affected. At least for PC, this only became true after Whiskey Lake. > > Kai-Heng > >> Alan Stern
This patch is included in Ubuntu’s kernel for a while now, and there’s no regression report so far. Please consider merge this patch.
Kai-Heng
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