Date: Wed, 15 Apr 2009 21:21:43 +0200 From: Andreas Tobler <andreast-list@fgznet.ch> To: Sean Bruno <sean.bruno@dsl-only.net> Cc: freebsd-firewire <freebsd-firewire@freebsd.org>, scottl <scottl@freebsd.org>, Marius Strobl <marius@alchemy.franken.de> Subject: Re: fwochi.c and bus_space_barrier() Message-ID: <49E633C7.9030909@fgznet.ch> In-Reply-To: <1239819547.15474.5.camel@localhost.localdomain> References: <1239382529.21481.7.camel@localhost.localdomain> <20090411154000.GG8143@alchemy.franken.de> <1239600457.24831.8.camel@localhost.localdomain> <49E2F2FA.6000204@fgznet.ch> <1239639423.24831.85.camel@localhost.localdomain> <20090413170537.GI8143@alchemy.franken.de> <1239643406.24831.95.camel@localhost.localdomain> <20090413173528.GJ8143@alchemy.franken.de> <1239646889.24831.135.camel@localhost.localdomain> <20090414184741.GK8143@alchemy.franken.de> <49E4DF9F.1090804@fgznet.ch> <1239814413.15474.2.camel@localhost.localdomain> <49E61B4D.1050209@fgznet.ch> <1239819547.15474.5.camel@localhost.localdomain>
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Sean Bruno wrote:
> On Wed, 2009-04-15 at 19:37 +0200, Andreas Tobler wrote:
>> Sean Bruno wrote:
>>>>> This looks basically good, but as outlined earlier a driver
>>>>> souldn't busy-wait 50ms. Could one of you please test whether
>>>>> pause("fwlps", (50 * hz + 999) / 1000) works as a drop-in
>>>>> replacement for DELAY(50000) here?
>>>> Works fine here!
>>>>
>>>> Thanks!
>>>> Andreas
>>>>
>>>>
>>>>
>>> Ok, time for more testing. A couple of changes here.
>>>
>>> 1. change busy DELAY() call with pause()
>>> 2. test for lps condition before pause(), if not set pause and retry.
>> Fine here, but see that there was no pause needed, strange.
>>
>> Andreas
>>
>>
> You may want to retry several times. Like you pointed out in earlier
> posts, this issue seems to be a race condition.
Heh, now I remember, I did not speak about a race condition, but about a
timing issue.
If I leave the printfs away, it panics here.
for (lps = 0, lps_counter = 0; !lps && lps_counter < 3; lps_counter++) {
lps = (OREAD(sc, OHCI_HCCCTL) & OHCI_HCC_LPS);
if (!lps) {
pause("fwlps", (50 * hz + 999) / 1000);
device_printf(dev, "lps not set,
attempt(%d)\n", lps_cou
nter);
} /* else
device_printf(dev, "lps(%0x) set\n", lps);*/
}
In my case the lps is not NULL, so we print something in the first run
of the loop, this print statement is enough 'time' for the card to come
up. If we leave the printf away, it is not enough time to come up for
the card. Panic.
This was the same thing I reported, adding a printf statement at the
beginning of fwphy_rddata cures my panic.
So I'd suggest to leave the lps test away and add always a pause(9), or
does this cause headache on other archs?
Thanks,
Andreas
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