Re: [PATCH] drm/i915: Don't enable hwmon for selftests

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Wed, 10 Apr 2024 04:42:46 -0700, Ville Syrjälä wrote:
>
> On Tue, Apr 09, 2024 at 09:28:55PM -0700, Ashutosh Dixit wrote:
> > There are no hwmon selftests so there is no need to enable hwmon for
> > selftests. So enable hwmon only for real driver load.
> >
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10366
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
>
> Why are we adding duct tape instead of fixing it properly?

Yeah pretty much what I said here myself:

https://patchwork.freedesktop.org/patch/588585/?series=132243&rev=1#comment_1071014

The issue has been difficult to root-cause. My last effort can be seen here:

https://patchwork.freedesktop.org/patch/584859/?series=131630&rev=1#comment_1067888

Though Badal went further and saw that occasionaly the memory would get
freed first and hwmon would get unregistered as much as 2 seconds later,
which will cause the crash if anyone touched hwmon sysfs in those final 2
seconds. So not sure what is causing that 2 second delay.

I am not sure if it is worth root-causing further. I am pretty sure if we
get rid of the devm_ stuff, that will fix the issue too. So if this patch
is not acceptable, we could just go that route (get rid of devm_ in hwmon).

Thanks.
--
Ashutosh

> > ---
> >  drivers/gpu/drm/i915/i915_driver.c | 16 ++++++++++++++--
> >  1 file changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> > index 9ee902d5b72c..6fa6d2c8109f 100644
> > --- a/drivers/gpu/drm/i915/i915_driver.c
> > +++ b/drivers/gpu/drm/i915/i915_driver.c
> > @@ -94,6 +94,7 @@
> >  #include "i915_memcpy.h"
> >  #include "i915_perf.h"
> >  #include "i915_query.h"
> > +#include "i915_selftest.h"
> >  #include "i915_suspend.h"
> >  #include "i915_switcheroo.h"
> >  #include "i915_sysfs.h"
> > @@ -589,6 +590,15 @@ static void i915_driver_hw_remove(struct drm_i915_private *dev_priv)
> >		pci_disable_msi(pdev);
> >  }
> >
> > +static bool is_selftest(void)
> > +{
> > +#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
> > +	return i915_selftest.live || i915_selftest.perf || i915_selftest.mock;
> > +#else
> > +	return false;
> > +#endif
> > +}
> > +
> >  /**
> >   * i915_driver_register - register the driver with the rest of the system
> >   * @dev_priv: device private
> > @@ -624,7 +634,8 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
> >
> >	intel_pxp_debugfs_register(dev_priv->pxp);
> >
> > -	i915_hwmon_register(dev_priv);
> > +	if (!is_selftest())
> > +		i915_hwmon_register(dev_priv);
> >
> >	intel_display_driver_register(dev_priv);
> >
> > @@ -660,7 +671,8 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
> >	for_each_gt(gt, dev_priv, i)
> >		intel_gt_driver_unregister(gt);
> >
> > -	i915_hwmon_unregister(dev_priv);
> > +	if (!is_selftest())
> > +		i915_hwmon_unregister(dev_priv);
> >
> >	i915_perf_unregister(dev_priv);
> >	i915_pmu_unregister(dev_priv);
> > --
> > 2.41.0
>
> --
> Ville Syrjälä
> Intel