Log spam from aspeed-video driver

[Joel Stanley]

On Tue, 25 Oct 2022 at 03:29, Zev Weiss <zev at bewilderbeest.net> wrote:
>
> Hi all,
>
> Since the recent update of the OpenBMC kernel to 6.0, I've been seeing a
> lot of new log noise from aspeed-video driver when the host is powered
> off after having been on:
>
>      [  335.526279] aspeed-video 1e700000.video: Timed out; first mode detect
>      [  335.544172] aspeed-video 1e700000.video: No signal; don't start frame
>      [  337.165555] aspeed-video 1e700000.video: Timed out; first mode detect
>      [  337.186214] aspeed-video 1e700000.video: No signal; don't start frame
>      [  338.815501] aspeed-video 1e700000.video: Timed out; first mode detect
>      [  338.834008] aspeed-video 1e700000.video: No signal; don't start frame
>
> It just emits that pair of messages continuously, about every 1.6
> seconds.

Our current generation machines don't use the bmc kvm setup, so this
hasn't seen much testing by IBM.

I'd like to hear from aspeed. If this is a problem with the driver
then it's something to look into. If it's log spam then we should put
it back to a dbg call.

>
> Looking through the commit history of the driver, it looks like that
> stems from commit a3de90afe392 ("media: aspeed: use
> v4l2_info/v4l2_warn/v4l2_dbg for log"), which converted a bunch of print
> calls from dev_dbg() to various v4l2_*() calls.  Reverting to the old
> 5.15 kernel (which didn't include that change), I found by enabling the
> dev_dbg() prints via sysfs (and cranking up the console loglevel) that
> the conditions triggering those messages have been happening all along,
> I just hadn't been seeing them because the debug prints were disabled by
> default.
>
> I should note that aside from the dmesg spam I don't see any functional
> problems with the driver; obmc-ikvm works as expected.
>
> Was switching those dev_dbg() calls to v4l2_warn() instead of v4l2_dbg()
> intentional?  Does this indicate some latent bug that should be fixed,
> or should they just be converted to v4l2_dbg()?
>
>
> Thanks,
> Zev
>