On Fri, Sep 3, 2021 at 12:39 PM John Stultz <john.stultz@xxxxxxxxxx> wrote: > > On Thu, Jul 29, 2021 at 1:49 PM Rob Clark <robdclark@xxxxxxxxx> wrote: > > On Thu, Jul 29, 2021 at 1:28 PM Caleb Connolly > > <caleb.connolly@xxxxxxxxxx> wrote: > > > On 29/07/2021 21:24, Rob Clark wrote: > > > > On Thu, Jul 29, 2021 at 1:06 PM Caleb Connolly > > > > <caleb.connolly@xxxxxxxxxx> wrote: > > > >> > > > >> Hi Rob, > > > >> > > > >> I've done some more testing! It looks like before that patch ("drm/msm: Devfreq tuning") the GPU would never get above > > > >> the second frequency in the OPP table (342MHz) (at least, not in glxgears). With the patch applied it would more > > > >> aggressively jump up to the max frequency which seems to be unstable at the default regulator voltages. > > > > > > > > *ohh*, yeah, ok, that would explain it > > > > > > > >> Hacking the pm8005 s1 regulator (which provides VDD_GFX) up to 0.988v (instead of the stock 0.516v) makes the GPU stable > > > >> at the higher frequencies. > > > >> > > > >> Applying this patch reverts the behaviour, and the GPU never goes above 342MHz in glxgears, losing ~30% performance in > > > >> glxgear. > > > >> > > > >> I think (?) that enabling CPR support would be the proper solution to this - that would ensure that the regulators run > > > >> at the voltage the hardware needs to be stable. > > > >> > > > >> Is hacking the voltage higher (although ideally not quite that high) an acceptable short term solution until we have > > > >> CPR? Or would it be safer to just not make use of the higher frequencies on a630 for now? > > > >> > > > > > > > > tbh, I'm not sure about the regulator stuff and CPR.. Bjorn is already > > > > on CC and I added sboyd, maybe one of them knows better. > > > > > > > > In the short term, removing the higher problematic OPPs from dts might > > > > be a better option than this patch (which I'm dropping), since there > > > > is nothing stopping other workloads from hitting higher OPPs. > > > Oh yeah that sounds like a more sensible workaround than mine . > > > > > > > > I'm slightly curious why I didn't have problems at higher OPPs on my > > > > c630 laptop (sdm850) > > > Perhaps you won the sillicon lottery - iirc sdm850 is binned for higher clocks as is out of the factory. > > > > > > Would it be best to drop the OPPs for all devices? Or just those affected? I guess it's possible another c630 might > > > crash where yours doesn't? > > > > I've not heard any reports of similar issues from the handful of other > > folks with c630's on #aarch64-laptops.. but I can't really say if that > > is luck or not. > > > > Maybe just remove it for affected devices? But I'll defer to Bjorn. > > Just as another datapoint, I was just marveling at how suddenly smooth > the UI was performing on db845c and Caleb pointed me at the "drm/msm: > Devfreq tuning" patch as the likely cause of the improvement, and > mid-discussion my board crashed into USB crash mode: > [ 146.157696][ C0] adreno 5000000.gpu: CP | AHB bus error > [ 146.163303][ C0] adreno 5000000.gpu: CP | AHB bus error > [ 146.168837][ C0] adreno 5000000.gpu: RBBM | ATB bus overflow > [ 146.174960][ C0] adreno 5000000.gpu: CP | HW fault | status=0x00000000 > [ 146.181917][ C0] adreno 5000000.gpu: CP | AHB bus error > [ 146.187547][ C0] adreno 5000000.gpu: CP illegal instruction error > [ 146.194009][ C0] adreno 5000000.gpu: CP | AHB bus error > [ 146.308909][ T9] Internal error: synchronous external abort: > 96000010 [#1] PREEMPT SMP > [ 146.317150][ T9] Modules linked in: > [ 146.320941][ T9] CPU: 3 PID: 9 Comm: kworker/u16:1 Tainted: G > W 5.14.0-mainline-06795-g42b258c2275c #24 > [ 146.331974][ T9] Hardware name: Thundercomm Dragonboar > Format: Log Type - Time(microsec) - Message - Optional Info > Log Type: B - Since Boot(Power On Reset), D - Delta, S - Statistic > S - QC_IMAGE_VERSION_STRING=BOOT.XF.2.0-00371-SDM845LZB-1 > S - IMAGE_VARIANT_STRING=SDM845LA > S - OEM_IMAGE_VERSION_STRING=TSBJ-FA-PC-02170 > > So Caleb sent me to this thread. :) > > I'm still trying to trip it again, but it does seem like db845c is > also seeing some stability issues with Linus' HEAD. > Caleb's original pastebin seems to have expired (or at least require some sort of ubuntu login to access).. were the crashes he was seeing also 'AHB bus error'? If you have a reliable reproducer, I guess it would be worth seeing if increasing the min_freq (ie. to limit how far we jump the freq in one shot) "fixes" it? I guess I could check downstream kgsl to see if they were doing something to increase freq in smaller increments.. I don't recall that they were but it has been a while since I dug thru that code. And I suppose downstream it could also be done in their custom tz governor. BR, -R