Messages in this thread | | | Date | Mon, 13 May 2013 10:15:32 -0400 (EDT) | From | Alan Stern <> | Subject | Re: usb: why we need a msleep(5) in ehci_bus_suspend/resume |
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On Mon, 13 May 2013, linux fddl wrote:
> Hi, > > From the ehci-hub.c, I find that ehci_bus_suspend/resume have some > code like this: > > if (time_before(jiffies, ehci->netx_statechange)) > msleep(5); > ... > ehci->next_statechange = jiffies + msec_to_jiffies(10); > > and > > if (time_before(jiffies, ehci->netx_statechange)) > msleep(5); > ... > ehci->next_statechange = jiffies + msec_to_jiffies(5); > > but I don't know why such a short sleep is needed, and why one is > [ehci->next_statechange = jiffies + msec_to_jiffies(10)] and the other is > [ehci->next_statechange = jiffies + msec_to_jiffies(5)], > I googled for a long time, but it seems that there is no explanation. > > Anyone knows why and can give any explanation?
At this point I don't think anybody knows. The person who originally wrote that code died a few years ago.
Alan Stern
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