Re: [PATCH v4] drm/i915: use hrtimer in wait for vblank

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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
-------------------
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/intel-gfx




[Index of Archives]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]
  Powered by Linux