On Mon, Jan 17, 2011 at 12:12:55PM +0000, Catalin Marinas wrote:
> On 17 January 2011 10:53, Russell King - ARM Linux
> <linux@xxxxxxxxxxxxxxxx> wrote:
> > On Mon, Jan 17, 2011 at 10:37:39AM +0000, Russell King - ARM Linux wrote:
> >> 3. Do we always need a dsb prior to a sev? Maybe the SPEAR patches need
> >> another review to determine how they're using sev()?
> >
> > FYI, this is how the SPEAR patches use sev():
> >
> > | +static void __init wakeup_secondary(void)
> > | +{
> > | + /* nobody is to be released from the pen yet */
> > | + pen_release = -1;
> > | +
> > | + /*
> > | + * Write the address of secondary startup into the system-wide
> > | + * location (presently it is in SRAM). The BootMonitor waits
> > | + * for this register to become non-zero.
> > | + * We must also send an sev to wake it up
> > | + */
> > | + __raw_writel(BSYM(virt_to_phys(spear13xx_secondary_startup)),
> > | + __io_address(SPEAR13XX_SYS_LOCATION));
> > | +
> > | + mb();
> > | +
> > | + /*
> > | + * Send a 'sev' to wake the secondary core from WFE.
> > | + */
> > | + sev();
> > | +}
> >
> > so the dsb() is inside mb(), before the outer sync call.
>
> BTW, don't we need some cache flushing for the pen_release?
Which is why I referred to "updated patch" - that's something which
all implementations suffered from until recently.
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