On Mon, Aug 05, 2019 at 09:48:13AM +0000, Pascal Van Leeuwen wrote:
> > On Wed, Jul 31, 2019 at 05:29:19PM +0200, Pascal van Leeuwen wrote:
> > >
> > > - /* Release engine from reset */
> > > - val = readl(EIP197_PE(priv) + ctrl);
> > > - val &= ~EIP197_PE_ICE_x_CTRL_SW_RESET;
> > > - writel(val, EIP197_PE(priv) + ctrl);
> > > + for (pe = 0; pe < priv->config.pes; pe++) {
> > > + base = EIP197_PE_ICE_SCRATCH_RAM(pe);
> > > + pollcnt = EIP197_FW_START_POLLCNT;
> > > + while (pollcnt &&
> > > + (readl_relaxed(EIP197_PE(priv) + base +
> > > + pollofs) != 1)) {
> > > + pollcnt--;
> >
> > You might want to use readl_relaxed_poll_timeout() here, instead of a
> > busy polling.
> >
> Didn't know such a thing existed, but I also wonder how appropriate it
> is in this case, condering it measures in whole microseconds, while the
> response time I'm expecting here is in the order of a few dozen nano-
> seconds internally ... i.e. 1 microsecond is already a *huge* overkill.
>
> The current implementation runs that loop for only 16 iterations which
> should be both more than sufficient (it probably could be reduced
> further, I picked 16 rather arbitrarily) and at the same time take so
> few cycles on the CPU that I doubt it is worthwhile to reschedule/
> preempt/whatever?
Your choice, I was just making a suggestion :)
Thanks,
Antoine
--
Antoine Ténart, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
