Re: [PATCH v2] drm/i915: Catch non-existent registers in find_fw_domain

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 07/12/2016 14:22, Joonas Lahtinen wrote:
> Add WARN_ON to find_fw_domain to registers related to uninitialized
> hardware.
>
> v2:
> - Print the uninitialized domains and register (Chris)
>
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Wang Elaine <elaine.wang@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 07779d0..88f3611 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -625,7 +625,14 @@ find_fw_domain(struct drm_i915_private *dev_priv, u32 offset)
>  			dev_priv->uncore.fw_domains_table_entries,
>  			fw_range_cmp);
>
> -	return entry ? entry->domains : 0;
> +	if (!entry)
> +		return 0;
> +
> +	WARN(entry->domains & ~dev_priv->uncore.fw_domains,
> +	     "Uninitialized forcewake domain(s) 0x%x accessed at 0x%x\n",
> +	     entry->domains & ~dev_priv->uncore.fw_domains, offset);
> +
> +	return entry->domains;
>  }
>
>  static void
>

Only slight issues I can spot is that for some platforms, should it 
trigger, it would trigger twice since 
intel_uncore_forcewake_for_read/write functions have the same WARN.

If we wanted to avoid that then this WARN would work better in 
fwtable_read/write I think.

Regards,

Tvrtko

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