Hi,
checking some patches thru www.kernel.org
I noticed something iffy in
/arch/arm/mach-omap2/omap_hwmod.c
in function
static int _reset(struct omap_hwmod *oh)
...
c = 0;
while (c < MAX_MODULE_RESET_WAIT &&
!(omap_hwmod_readl(oh, oh->sysconfig->syss_offs) &
SYSS_RESETDONE_MASK)) {
udelay(1);
c++;
}
if (c == MAX_MODULE_RESET_WAIT)
WARN(1, "omap_hwmod: %s: failed to reset in %d usec\n",
oh->name, MAX_MODULE_RESET_WAIT);
else
pr_debug("omap_hwmod: %s: reset in %d usec\n", oh->name, c);
/*
* XXX add _HWMOD_STATE_WEDGED for modules that don't come back from
* _wait_target_ready() or _reset()
*/
return (c == MAX_MODULE_RESET_WAIT) ? -ETIMEDOUT : 0;
...
Let's assume MAX_MODULE_RESET_WAIT==1,
and let's look what happens with the "reset" while loop,
in case where we exit the loop at the last possible
moment.
c==0, and rest not done so udelay(1), c=1.
We do not loop another time because c==MAX_MODULE_RESET_WAIT.
So we give a warning and return -ETIMEDOUT.
Hmmm, we did not check if reset was done while udelay?
Still we warn that "failed to reset in 1 usec"!
Simple correction could be something like
.....
c = 0;
- while (c < MAX_MODULE_RESET_WAIT &&
- !(omap_hwmod_readl(oh, oh->sysconfig->syss_offs) &
- SYSS_RESETDONE_MASK)) {
- udelay(1);
- c++;
- }
+ while (!(omap_hwmod_readl(oh, oh->sysconfig->syss_offs) &
+ SYSS_RESETDONE_MASK) &&
+ (c++ < MAX_MODULE_RESET_WAIT))
+ udelay(1);
- if (c == MAX_MODULE_RESET_WAIT)
+ if (c > MAX_MODULE_RESET_WAIT)
WARN(1, "omap_hwmod: %s: failed to reset in %d usec\n",
<SNIP>
- return (c == MAX_MODULE_RESET_WAIT) ? -ETIMEDOUT : 0;
+ return (c > MAX_MODULE_RESET_WAIT) ? -ETIMEDOUT : 0;
.....
Now we do max MAX_MODULE_RESET_WAIT udelay(1)'s and
always check after udelay(1) if resetdone.
Signed-off-by: "Juha Leppanen" <juha_motorsportcom@xxxxxxxxxx>
No reply needed to me,
my spam filter will probably eat your reply.
Reported-by: "Juha Leppanen" <juha_motorsportcom@xxxxxxxxxx>
tag would be nice in kernel.org :)
Not so many kernel hackers give credit these days :(
Happy hacking,
Mr. Juha Leppanen
Kuopio, Finland
....................................................................
Luukku Plus -paketilla pääset eroon tila- ja turvallisuusongelmista.
Hanki Luukku Plus ja helpotat elämääsi. http://www.mtv3.fi/luukku
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