[PATCH 03/11] drm/i915/display: convert inner wakeref get towards get_if_in_use

[Francois Dugast]

On Thu, Mar 14, 2024 at 10:10:13AM -0400, Rodrigo Vivi wrote:
> This patch brings no functional change. Since at this point of
> the code we are already asserting a wakeref was held, it means
> that we are with runtime_pm 'in_use' and in practical terms we
> are only bumping the pm_runtime usage counter and moving on.
> 
> However, xe driver has a lockdep annotation that warned us that
> if a sync resume was actually called at this point, we could have
> a deadlock because we are inside the power_domains->lock locked
> area and the resume would call the irq_reset, which would also
> try to get the power_domains->lock.
> 
> For this reason, let's convert this call to a safer option and
> calm lockdep on.
> 
> v2: use _noresume variant instead of get_in_use (Ville, Imre)
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Acked-by: Imre Deak <imre.deak at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

Reviewed-by: Francois Dugast <francois.dugast at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_display_power.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 6fd4fa52253a..048943d0a881 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -646,7 +646,7 @@ release_async_put_domains(struct i915_power_domains *power_domains,
>  	 * power well disabling.
>  	 */
>  	assert_rpm_raw_wakeref_held(rpm);
> -	wakeref = intel_runtime_pm_get(rpm);
> +	wakeref = intel_runtime_pm_get_noresume(rpm);
>  
>  	for_each_power_domain(domain, mask) {
>  		/* Clear before put, so put's sanity check is happy. */
> -- 
> 2.44.0
>