On Fri, Oct 26, 2012 at 09:27:52AM +0200, Jean Delvare wrote: > Hi Guenter, > > On Thu, 25 Oct 2012 17:41:15 -0700, Guenter Roeck wrote: > > On Thu, Oct 25, 2012 at 04:49:01PM -0700, Guenter Roeck wrote: > > > > I don't get it. I have double checked my code and I don't see how this > > > > is possible. Plus Guenter's testing was successful... > > > > > > Doesn't work for me either on NCT6776F. Some of the data is restored, which is > > > not the case if I use the "old" driver, so I must have used the correct driver. > > > > Hi Jean, > > > > I found the problem. The NCT6776F has the wrong bank selected when resuming. > > > > It started working for me after adding > > > > data->bank = 0xff; > > > > to the beginning of the resume function. This forces the bank register to be > > updated when the first chip access is done. > > Wow, very good catch, thanks a lot. That explains it all. I couldn't > see this in the dumps I asked for, as these dumps do force the bank to > a specific value. > Yes, that was a lucky catch. I didn't find it from the dumps, but by adding debug code to the resume function. And when reading back the register values it was quite obvious what happpened. > Now I think we have a bug in the w83627ehf driver. data->bank is never > initialized, so it default to 0 per kzalloc of data. If the driver > reads a register from bank 0 first, and this wasn't the currently > selected bank at hardware level, it will read from the wrong register. > I had briefly wondered how we know that bank 0 is selected initially :). > We are lucky that the driver always reads register > NCT6775_REG_TEMP_SOURCE[0] == 0x621 first for the NCT677x chips. For > other chips only registers 0x50-0x5F are banked. For the W83667HG and > W83667HG-B we read W83627EHF_REG_TEMP_CONFIG[2] == 0x252 first so we > are lucky once more. For older chips we could be in trouble depending > on the initial bank setting and chip configuration. > > I'll send a fixup patch in a minute. > > > It might make sense to do this for all chips with bank registers. > > Depends on how bank switching is implemented. For example the w83627hf > driver doesn't make any assumption on the currently selected bank, it > always sets the bank (even if it is 0) before accessing a register in > the banked area. Which is why my own testing with the w83627hf driver Yes, I noticed. > was successful. > My testing with NCT6775 was successful as well, so the lucky part may be that my Asus board selects another bank during resume.... Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
