On Tuesday 25 March 2014 03:02 PM, Jani Nikula wrote:
On Tue, 25 Mar 2014, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
On Tue, Mar 25, 2014 at 02:28:22PM +0530, Arun R Murthy wrote:
In wait for vblank use usleep_range, which will use hrtimers instead of
msleep. Using msleep(1~20) there are more chances of sleeping for 20ms.
Using usleep_range uses hrtimers and hence are precise, worst case will
trigger an interrupt at the higher/max timeout.
As per kernel document "Documentation/timers/timers-howto.txt" sleeping
for 10us to 20ms its recomended to use usleep_range.
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
Lgtm, I still feel that our use of W=1 is fairly arbitrary and worth
tweaking in future.
With the current code, this is essentially the same as the original
patch. We never have W > 20, and thus we always take the usleep_range()
path. So W is definitely worth tweaking if we go with this now.
Nitpick, the macro params should be parenthesized. This will now break
for _wait_for(cond, 10, 2 + 1) and such.
wait_for(COND, TIMEOUT, ATOMIC, MS)
and remove all wait_for_X
function will look like
_wait_for(COND< TIMEOUT, ATOMIC, MS)
{
/* loop */
/* check condition */
if (atomic)
cpu_relax()
else
if (ms > 20)
msleep
else
usleep_range
}
caller for wait_for will be setting all the parameters and hence no tweaks.
Thanks and Regards,
Arun R Murthy
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