On Fri, Mar 06, 2009 at 12:17:37PM -0600, Asim wrote:
> I need it for a device. The device performs some operation in a loop
> but I cannot wait in that loop forever, so I need to wait for the
> maximum time I can (2 clock ticks) before giving up on the device.
> Interrupts may be disabled so I cannot use jiffies. Any simple
> solution would be appreciated.
Do what is done in lots of places in the kernel, something like the
following from drivers/usb/host/pci-quirks.c:
/* if boot firmware now owns EHCI, spin till
* it hands it over.
*/
msec = 1000;
while ((cap & EHCI_USBLEGSUP_BIOS) && (msec > 0)) {
tried_handoff = 1;
msleep(10);
msec -= 10;
pci_read_config_dword(pdev, offset, &cap);
}
Don't think in "clock ticks" but rather in "real" units of time, like
portions of seconds. That way your code will work properly when a
"clock tick" changes over time, becoming faster or slower, as they
always do.
Hope this helps,
greg k-h
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