Hello Michal,
> From: Michal Simek <[email protected]>
> On 5/18/26 14:07, Maarten Brock wrote:
> >> From: Michal Simek <[email protected]>
> >> On 5/18/26 12:21, Maarten Brock wrote:
> >>
> >> I expect you would like to do it like this right?
> >>
> >> int reset_reset_bulk(struct reset_ctl_bulk *bulk, ulong delay_us)
> >> {
> >> int ret;
> >>
> >> ret = reset_assert_bulk(bulk);
> >> if (ret) {
> >> dev_err(bus, "Failed to assert reset: %d\n", ret);
> >> return ret;
> >> }
> >>
> >> udelay(delay_us);
> >>
> >> /* Deassert all OSPI reset lines */
> >> ret = reset_deassert_bulk(bulk);
> >> if (ret) {
> >> dev_err(bus, "Failed to deassert reset: %d\n", ret);
> >> return ret;
> >> }
> >>
> >> return 0;
> >> }
> >
> > That is correct.
> > And a single delay of delay_us takes less time than N*delay_us (for N>1),
> > so the total startup time is smaller (a.k.a. faster startup).
>
> It really depends on other factors and delay time. In our case it is not just
> MMIO access. But it is SMC to TF-A and then seconding request over mailbox to
> another firmware to ack it first and then do it. And with above you would have
> to do twice compare to once.
>
> I can do another optimization which is that if bulk->count is 1 then call
> reset_reset() directly and for others do what you see above.
>
> What do you think?
I very much doubt that all sorts of actions and compares will ever take more
time than 1 us, unless some serial protocol is involved (uart/spi/i2c).
So, I expect that delay_us is always the dominant elapsed time. And N*delay_us
even more so.
I do understand that if the delay is handled by rst_reset() and underlying
hardware, things might be different.
So special handling of bulk->count=1 or *all* bulk resets are handled by
rst_reset() could be a good idea.
How about something like this?
int reset_reset_bulk(struct reset_ctl_bulk *bulk, ulong delay_us)
{
int i, ret, soft = 0;
for (i = 0; i < bulk->count; i++) {
struct reset_ops *ops = reset_dev_ops(bulk->resets[i].dev);
if (ops->rst_reset) {
ret = ops->rst_reset(&bulk->resets[i], delay_us);
} else {
ret = reset_assert(&bulk->resets[i]);
soft++;
}
if (ret < 0)
return ret;
}
if (soft == 0)
return 0;
udelay(delay_us);
for (i = 0; i < bulk->count; i++) {
struct reset_ops *ops = reset_dev_ops(bulk->resets[i].dev);
if (!ops->rst_reset) {
ret = reset_deassert(&bulk->resets[i]);
if (ret < 0)
return ret;
}
}
return 0;
}
Kind regards,
Maarten Brock
