[igt-dev] [PATCH] lib/igt_kmod: Make sure the mei modules are loaded when i915 is

[Dixit, Ashutosh]

On Mon, 10 Oct 2022 12:01:07 -0700, Daniele Ceraolo Spurio wrote:
>

Hi Daniele,

> The mei modules are required on DG2 to use the GSC child device, which
> is in turn responsible for loading HuC. We're observing a sporadic
> failure in CI (see ref below) where it looks like the mei modules are
> not automatically loaded by the kernel the fist time i915 exposes the
> child device while being loaded by IGT, but are then loaded fine when
> i915 is reloaded by another test later on.
>
> To make sure that the modules get loaded, explicitly modprobe them after
> i915 is loaded.
>
> References: https://gitlab.freedesktop.org/drm/intel/-/issues/7029
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: John Harrison <john.c.harrison at intel.com>
> Cc: Alan Previn <alan.previn.teres.alexis at intel.com>
> ---
>  lib/igt_kmod.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
> index bcf7dfeb..c9a9c2db 100644
> --- a/lib/igt_kmod.c
> +++ b/lib/igt_kmod.c
> @@ -394,6 +394,9 @@ igt_i915_driver_load(const char *opts)
>	}
>
>	bind_fbcon(true);
> +	igt_kmod_load("mei_gsc", NULL);
> +	igt_kmod_load("mei_hdcp", NULL);
> +	igt_kmod_load("mei_pxp", NULL);

Afaiu there should be no need to do this, correct? If the device appears
the driver should automatically load and bind to the device. So doing this
explicity as above can hide issues in this process.

To me the sporadic nature of this issue seems to indicate something wrong
in the kernel rather than in IGT, which we are trying to paper over with
this patch. Not sure.

At least have we verified that doing this fix the issue, have we checked?
Since the repro rate for GL #7029 is 76% it should be possible to verify or
does it always pass in IGT pre-merge? At least the one run in Patchwork
everything is passing.

Also maybe we should add some debug prints to gem_huc_copy.c which checks
whether the module is not loaded when the test fails? Or is the module
loaded but not binding to the device?

There are many "[drm] mei driver not bound, disabling HuC load" in dmesg.

Or maybe instead of doing this in the lib here we do something in
gem_huc_copy.c? Can we reload i915 in gem_huc_copy.c when starting the test
or load these modules in gem_huc_copy.c e.g.?

Also do we only need to load these modules on platforms on which they are
needed? Otherwise we will generate unnecessary "could not insert module"
debug messages?

So mostly I am not comfortable with this patch. Can we get a second
opinion?

Thanks.
--
Ashutosh

>	igt_kmod_load("snd_hda_intel", NULL);
>
>	return 0;
> --
> 2.37.3
>