lkml.org 
[lkml]   [2020]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] thermal: sun8i: Be loud when probe fails
    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

    \
     
     \ /
      Last update: 2020-07-23 17:22    [W:3.455 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site