| Message ID | 20091014230252.0d0cba8d@hyperion.delvare (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Wed, 2009-10-14 at 23:02 +0200, Jean Delvare wrote: > Hi all, > > On Tue, 13 Oct 2009 11:49:48 +0200, Jean Delvare wrote: > > I2C bus being setup too fast sounds more likely. It might be worth > > adding an arbitrary delay after initialization, just to see if it > > helps. Not sure where though, as I'm not familiar with the Powermac > > initialization steps. Maybe right before i2c_add_adapter() in > > i2c_powermac_probe? > > Tim, can you please give a try to this patch? Obviously your machine > will take 5 additional seconds to boot, and this isn't meant as a real > fix, but if it helps, this will be an interesting hint for further > debugging attempts. Oh, I was actually thinking about the frequency of the I2C clock :-) Cheers, Ben. > --- kernel32.orig/drivers/macintosh/therm_adt746x.c > +++ kernel32/drivers/macintosh/therm_adt746x.c > @@ -380,6 +380,7 @@ static int probe_thermostat(struct i2c_c > if (thermostat) > return 0; > > + msleep(5000); > th = kzalloc(sizeof(struct thermostat), GFP_KERNEL); > if (!th) > return -ENOMEM; > >
On Thu, 15 Oct 2009 08:26:15 +1100, Benjamin Herrenschmidt wrote: > On Wed, 2009-10-14 at 23:02 +0200, Jean Delvare wrote: > > Hi all, > > > > On Tue, 13 Oct 2009 11:49:48 +0200, Jean Delvare wrote: > > > I2C bus being setup too fast sounds more likely. It might be worth > > > adding an arbitrary delay after initialization, just to see if it > > > helps. Not sure where though, as I'm not familiar with the Powermac > > > initialization steps. Maybe right before i2c_add_adapter() in > > > i2c_powermac_probe? > > > > Tim, can you please give a try to this patch? Obviously your machine > > will take 5 additional seconds to boot, and this isn't meant as a real > > fix, but if it helps, this will be an interesting hint for further > > debugging attempts. > > Oh, I was actually thinking about the frequency of the I2C clock :-) Oh. Well, if that was the case, we would see errors all the time, not just during initialization, right? Or does the I2C clock frequency change over time somehow?
On Thu, 2009-10-15 at 12:49 +0200, Jean Delvare wrote: > Oh. Well, if that was the case, we would see errors all the time, not > just during initialization, right? Or does the I2C clock frequency > change over time somehow? No but maybe we are a bit on the "limit" of the device and some registers take long to respond than others ? Cheers, Ben.
On Thu, 15 Oct 2009 22:19:19 +1100, Benjamin Herrenschmidt wrote: > On Thu, 2009-10-15 at 12:49 +0200, Jean Delvare wrote: > > Oh. Well, if that was the case, we would see errors all the time, not > > just during initialization, right? Or does the I2C clock frequency > > change over time somehow? > > No but maybe we are a bit on the "limit" of the device and some > registers take long to respond than others ? Unlikely. The ADT7460 can run at I2C clock rates up to 400 kHz while the Keywest I2C runs at 25, 50 or 100 kHz if I read the code properly. I don't know what exact speed is used on Tim's system, apparently it is read from the hardware in the device tree directly? We could have low_i2c.c log the I2C clock frequency and/or try to force the lowest speed (25 kHz) and see if it helps, but I very much doubt it. And I'd rather wait for Tim to report the result with my last patch first.
On Thu, 15 Oct 2009 16:05:13 +0200, Jean Delvare wrote: > On Thu, 15 Oct 2009 22:19:19 +1100, Benjamin Herrenschmidt wrote: > > On Thu, 2009-10-15 at 12:49 +0200, Jean Delvare wrote: > > > Oh. Well, if that was the case, we would see errors all the time, not > > > just during initialization, right? Or does the I2C clock frequency > > > change over time somehow? > > > > No but maybe we are a bit on the "limit" of the device and some > > registers take long to respond than others ? > > Unlikely. The ADT7460 can run at I2C clock rates up to 400 kHz while > the Keywest I2C runs at 25, 50 or 100 kHz if I read the code properly. > I don't know what exact speed is used on Tim's system, apparently it is > read from the hardware in the device tree directly? > > We could have low_i2c.c log the I2C clock frequency and/or try to force > the lowest speed (25 kHz) and see if it helps, but I very much doubt > it. And I'd rather wait for Tim to report the result with my last patch > first. Ben, wouldn't this recent patch of yours be worth testing too? http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=11a50873ef2b3c1c3fe99a661c22c08f35d93553 If it solves problems at resume time, I guess it might also solve problems at boot time?
On Fri, 2009-10-16 at 09:44 +0200, Jean Delvare wrote: > On Thu, 15 Oct 2009 16:05:13 +0200, Jean Delvare wrote: > > On Thu, 15 Oct 2009 22:19:19 +1100, Benjamin Herrenschmidt wrote: > > > On Thu, 2009-10-15 at 12:49 +0200, Jean Delvare wrote: > > > > Oh. Well, if that was the case, we would see errors all the time, not > > > > just during initialization, right? Or does the I2C clock frequency > > > > change over time somehow? > > > > > > No but maybe we are a bit on the "limit" of the device and some > > > registers take long to respond than others ? > > > > Unlikely. The ADT7460 can run at I2C clock rates up to 400 kHz while > > the Keywest I2C runs at 25, 50 or 100 kHz if I read the code properly. > > I don't know what exact speed is used on Tim's system, apparently it is > > read from the hardware in the device tree directly? > > > > We could have low_i2c.c log the I2C clock frequency and/or try to force > > the lowest speed (25 kHz) and see if it helps, but I very much doubt > > it. And I'd rather wait for Tim to report the result with my last patch > > first. > > Ben, wouldn't this recent patch of yours be worth testing too? > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=11a50873ef2b3c1c3fe99a661c22c08f35d93553 > > If it solves problems at resume time, I guess it might also solve > problems at boot time? I doubt it. The problem was related to the way interrupts get turned off at suspend time by the generic code, which is unrelated to what happens at boot. Cheers, Ben.
--- kernel32.orig/drivers/macintosh/therm_adt746x.c +++ kernel32/drivers/macintosh/therm_adt746x.c @@ -380,6 +380,7 @@ static int probe_thermostat(struct i2c_c if (thermostat) return 0; + msleep(5000); th = kzalloc(sizeof(struct thermostat), GFP_KERNEL); if (!th) return -ENOMEM;