On Thu, Oct 9, 2014 at 4:14 PM, Felipe Balbi <balbi@xxxxxx> wrote:
> On Thu, Oct 09, 2014 at 01:45:47PM +0900, Yoshihiro Shimoda wrote:
>> This patch fixes an issue that suspend/resume cannot work correctly
>> on xhci-rcar because the xhci driver output the following log:
>>
>> xhci-hcd ee000000.usb: WARN: xHC CMD_RUN timeout
>>
>> So, this patch adds to set the XHCI_SLOW_SUSPEND quirk if xhci-rcar.
>
> do you have erratum number confirming this is needed for your platform ?
> We really don't want to enable quirks just because they help, we need to
> be sure HW is quirky. For example, we triggered the same thing on DRA7xx
> (which uses dwc3) but after digging a little, it seems like we're having
> memory access latency issues, not a problem with XHCI.
FWIW, xhci_handshake() runs a tight loop around udelay(1) for up to 16 ms
(160 ms when the quirk is enabled --- not counting loop overhead),
which looks like an area for improvement.
As the individual udelay() calls wait for only 1 us, the __bad_udelay()
sanity check "Use only for very small delays ( < 2 msec)" doesn't kick in.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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