Messages in this thread |  | | Date | Thu, 23 Jul 2020 17:20:54 +0200 | From | Maxime Ripard <> | Subject | Re: [PATCH] thermal: sun8i: Be loud when probe fails |
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On Mon, Jul 13, 2020 at 01:29:42AM +0200, Ondřej Jirman wrote: > Hi Maxime, > > On Wed, Jul 08, 2020 at 03:57:48PM +0200, Maxime Ripard wrote: > > On Wed, Jul 08, 2020 at 03:44:41PM +0200, Ondřej Jirman wrote: > > > > > > [...] > > > > > Yeah, but on the other hand, we regularly have people that come up and > > > > ask if a "legitimate" EPROBE_DEFER error message (as in: the driver > > > > wasn't there on the first attempt but was there on the second) is a > > > > cause of concern or not. > > > > > > That's why I also added a success message, to distinguish this case. > > > > That doesn't really help though. We have plenty of drivers that have > > some sort of success message and people will still ask about that error > > message earlier. > > > > > > > And people run several distros for 3-4 months without anyone noticing any > > > > > issues and that thermal regulation doesn't work. So it seems that lack of a > > > > > success message is not enough. > > > > > > > > I understand what the issue is, but do you really expect phone users to > > > > monitor the kernel logs every time they boot their phone to see if the > > > > thermal throttling is enabled? > > > > > > Not phone users, but people making their own kernels/distributions. Those people > > > monitor dmesg, and out of 4 distros or more nobody noticed there was an issue > > > (despite the complaints of overheating by their users). > > > > > > So I thought some warning may be in order, so that distro people more easily > > > notice they have misconfigured the kernel or sometging. > > > > I mean, then there's nothing we can do to properly address that then. > > > > The configuration system is a gun, we can point at the target, but > > anyone is definitely free to shot themself in the foot. > > > > You would have exactly the same result if you left the thermal driver > > disabled, or if you didn't have cpufreq support. > > Right. Though I hope there's some middle ground. I mean all of those dev_err > in error paths of many drivers are there mostly to help debugging stuff.
Adding all the error messages you have in that patch seems like a good middle ground to me, and we could definitely use more of them in some other drivers (like the USB PHY)
> And even though I was part of this driver's development, it took me quite > some time to figure out it was the missing sunxi-sid driver causing the issue, > with complete silence from the driver. > > Maybe this can/will be solved at another level entirely, like having a device > core report devices probes that failed with EPROBE_DEFER some time after > the boot finished and modules had a chance to load, instead of immediately > for each probe retry.
The thing is that there's never a point in time where "all the modules had a chance to load". If you're loading the modules on demand and have an hotpluggable bus, that might happen after a second or after a year, you can't say.
The actual fix for this would be to use the on demand probing that seems to be in the works and avoid EPROBE_DEFER entirely, but that probably won't happen in a near future.
Maxime
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