On 01/28/2018 04:05 PM, Martin Peres wrote: > On 29/01/18 01:24, Martin Peres wrote: >> On 28/11/17 07:32, John Hubbard wrote: >>> On 11/23/2017 02:48 PM, Martin Peres wrote: >>>> On 23/11/17 10:06, John Hubbard wrote: >>>>> On 11/22/2017 05:07 PM, Martin Peres wrote: >>>>>> Hey, >>>>>> >>>>>> Thanks for your answer, Andy! >>>>>> >>>>>> On 22/11/17 04:06, Ilia Mirkin wrote: >>>>>>> On Tue, Nov 21, 2017 at 8:29 PM, Andy Ritger <arit...@nvidia.com> wrote: >>>>>>> Martin's question was very long, but it boils down to this: >>>>>>> >>>>>>> How do we compute the correct values to write into the e114/e118 pwm >>>>>>> registers based on the VBIOS contents and current state of the board >>>>>>> (like temperature). >>>>>> >>>>>> Unfortunately, it can also be the e11c/e120 couple, or 0x200d8/dc on >>>>>> GF119+, or 0x200cd/d0 on Kepler+. >>>>>> >>>>>> At least, it looks like we know which PWM controler we need to drive, so >>>>>> I did not want to muddy the water even more by giving register >>>>>> addresses, rather concentrating on the problem at hand: How to compute >>>>>> the duty value for the PWM controler. >>>>>> >>>>>>> >>>>>>> We generally do this right, but appear to get it extra-wrong for >>>>>>> certain GPUs. >>>>>> >>>>>> Yes... So far, we are always safe, but users tend to mind when their >>>>>> computer sound like a jumbo jet at take off... Who would have thought? :D >>>>>> >>>>>> Anyway, looking forward to your answer! >>>>>> >>>>>> Cheers, >>>>>> Martin >>>>> >>>>> >>>>> Hi Martin, >>>>> >>>>> One of our firmware engineers thinks that this looks a lot like PWM >>>>> inversion. >>>>> For some SKUs, the interpretation of the PWM duty cycle is inverted. That >>>>> would probably make it *very* difficult to find a sensible algorithm that >>>>> covered all the SKUs, given that some are inverted and others are not. >>>>> >>>>> For the noisy GPUs, a very useful experiment would be to try inverting >>>>> it, >>>>> like this: >>>>> >>>>> pwmDutyCycle = pwmPeriod - pwmDutyCycle; >>>>> >>>>> ...and then see if fan control starts behaving closer to how you've >>>>> actually >>>>> programmed it. >>>>> >>>>> Would that be easy enough to try out? It should help narrow down the >>>>> problem at least. >>>>> >>>> >>>> Hey John, >>>> >>>> Unfortunately, we know about PWM inversion, and one can know which mode >>>> to use based on the GPIO entry associated to the fan (inverted). We have >>>> had support for this in Nouveau for a long time. At the very least, this >>>> is not the problem on my GF108. >>>> >>>> I am certain that the problem I am seeing is related to this vbios table >>>> I wrote about (BIT P, offset 0x18). It is used to compute what PWM duty >>>> I should use for both 0 and 100% of the fan speed. >>>> >>>> Computing the value for 0% fan speed is difficult because of >>>> non-continuous nature of some of the functions[1], but I can always >>>> over-approximate. However, I failed to accurately compute the duty I >>>> need to write to get the 100% fan speed (I have cases where I greatly >>>> over-estimate it...). >>>> >>>> Could you please check out the vbios table I am pointing at? I am quite >>>> sure that your documentation will be clearer than my babbling :D >>> >>> Yes. We will check on this. There has been some productive discussion >>> internally, but it will take some more investigation. >>> >>> thanks, >>> John Hubbard >> >> Have the productive discussions panned out?
Yes, we concluded our discussions, and decided that I should study the situation and write some documentation. I just finished my research and writeup late last Friday, though, so my colleagues haven't had a chance to review it. Not to put undue pressure on them, but I'm hoping that will go quickly now. The long pole is done. :) I was going to wait until the review was done, to respond, but I wanted to ACK this and to let you know that I do realize that the tables below are not directly answering your question. (What happened here is: the new tables below are not actually what I've personally been working on; they just happen to be a very good set of supporting documentation in the exact same area. One of our teammates was already working on these independently, and managed to get them released.) thanks, -- John Hubbard > > Oh, I see you pushed new vbios documentation: > 1) > http://download.nvidia.com/open-gpu-doc/BIOS-Information-Table/1/BIOS-Information-Table.html > 2) > http://download.nvidia.com/open-gpu-doc/MemoryClockTable/1/MemoryClockTable.html > 3) > http://download.nvidia.com/open-gpu-doc/MemoryTweakTable/1/MemoryTweakTable.html > > Is there any chance to get the documentation of the "Thermal Coolers > Table", and the "Thermal Device Table" (the latter does not seem super > important though). > > Anyway, thanks for the new documentation, reverse engineering of power > management will be greatly simplified as we have a better idea which > bits will control what. Too bad it won't help for the current issue > though... > > Thanks, > Martin > _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/nouveau
