Response inline.
On 15-02-25 11:17 AM, Arnd Bergmann wrote:
On Wednesday 25 February 2015 10:16:24 Scott Branden wrote:
This adds a driver for random number generator present on Broadcom
IPROC devices.
Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx>
Signed-off-by: Scott Branden <sbranden@xxxxxxxxxxxx>
The driver looks reasonable overall, I have just one question about
something that sticks out:
+ while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {
...
+
+ /* Are there any random numbers available? */
+ if ((ioread32(rng_base + RNG_FIFO_COUNT_OFFSET) &
+ RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {
...
+ } else {
+ if (!wait)
+ /* Cannot wait, return immediately */
+ return max - num_remaining;
+
+ /* Can wait, give others chance to run */
+ cpu_relax();
+ }
+ }
+
It looks like you do a busy-loop around cpu_relax here if asked to wait.
Is this intentional? I would normally expect either cond_resched() or
some msleep() instead.
This code was following examples of other open source drivers - bcm2835
and exynos both use cpu_relax. I'll have to look into this more to
understand.
Arnd
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
