[PATCH v7 1/5] drm: Introduce device wedged event

[Andy Shevchenko]

On Mon, Sep 30, 2024 at 01:08:41PM +0530, Raag Jadav wrote:
> Introduce device wedged event, which will notify userspace of wedged
> (hanged/unusable) state of the DRM device through a uevent. This is
> useful especially in cases where the device is no longer operating as
> expected even after a hardware reset and has become unrecoverable from
> driver context.
> 
> Purpose of this implementation is to provide drivers a generic way to
> recover with the help of userspace intervention. Different drivers may
> have different ideas of a "wedged device" depending on their hardware
> implementation, and hence the vendor agnostic nature of the event.
> It is up to the drivers to decide when they see the need for recovery
> and how they want to recover from the available methods.
> 
> Current implementation defines three recovery methods, out of which,
> drivers can choose to support any one or multiple of them. Preferred
> recovery method will be sent in the uevent environment as WEDGED=<method>.
> Userspace consumers (sysadmin) can define udev rules to parse this event
> and take respective action to recover the device.
> 
>     =============== ==================================
>     Recovery method Consumer expectations
>     =============== ==================================
>     rebind          unbind + rebind driver
>     bus-reset       unbind + reset bus device + rebind
>     reboot          reboot system
>     =============== ==================================

...

> +/*
> + * Available recovery methods for wedged device. To be sent along with device
> + * wedged uevent.
> + */
> +static const char *const drm_wedge_recovery_opts[] = {
> +	[DRM_WEDGE_RECOVERY_REBIND] = "rebind",
> +	[DRM_WEDGE_RECOVERY_BUS_RESET] = "bus-reset",
> +	[DRM_WEDGE_RECOVERY_REBOOT] = "reboot",
> +};

Place for static_assert() is here, as it closer to the actual data we test...

> +static bool drm_wedge_recovery_is_valid(enum drm_wedge_recovery method)
> +{
> +	static_assert(ARRAY_SIZE(drm_wedge_recovery_opts) == DRM_WEDGE_RECOVERY_MAX);

...it doesn't fully belong to this function (or only to this function).

> +	return method >= DRM_WEDGE_RECOVERY_REBIND && method < DRM_WEDGE_RECOVERY_MAX;
> +}

Why do we need this one-liner (after above comment being addressed) as a
separate function?

-- 
With Best Regards,
Andy Shevchenko