Re: [PATCH 03/11] drm/i915/display: convert inner wakeref get towards get_if_in_use
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
> Acked-by: Imre Deak
> Cc: Matthew Auld
> Signed-off-by: Rodrigo Vivi
Reviewed-by: Francois Dugast
> ---
> 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
>
[PATCH 03/11] drm/i915/display: convert inner wakeref get towards get_if_in_use
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
Acked-by: Imre Deak
Cc: Matthew Auld
Signed-off-by: Rodrigo Vivi
---
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
[PATCH 03/11] drm/i915/display: convert inner wakeref get towards get_if_in_use
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
Acked-by: Imre Deak
Cc: Matthew Auld
Signed-off-by: Rodrigo Vivi
---
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
