Re: [Intel-gfx] [PATCH v4 13/14] drm/i915/tc: Call TypeC port flush_work/cleanup without modeset locks held

Ville Syrjälä
2023-05-10T14:03:47Z

On Wed, May 10, 2023 at 01:31:30PM +0300, Imre Deak wrote:
> Call the TypeC port flush_work and cleanup handlers without the modeset
> locks held. These don't require the locks, as the work takes - as it
> should be able to at any point in time - any locks it needs and by the
> time cleanup is called and after cleanup returns the encoder is not in
> use.
>
> This is required by the next patch canceling a TypeC port work
> synchronously during encoder suspend and shutdown, where the work can
> take modeset locks as well, hence the canceling must be done without
> holding the locks.
>
> I also considered moving the modeset locking down to each encoder
> suspend()/shutdown() hook instead, however locking the full modeset
> state for each encoder separately would be odd, and the bigger change -
> affecting all encoders - is beyond the scope of this patchset.

Hmm. What is it in the encoder shutdown/suspend hooks that
actually needs the modeset locks?

>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 27 +++++++++----------
> .../drm/i915/display/intel_display_types.h | 12 +++++++++
> drivers/gpu/drm/i915/i915_driver.c | 8 ++++++
> 3 files changed, 33 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 813be957ed11b..7d09bd2412352 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -4617,31 +4617,27 @@ static bool intel_ddi_is_tc(struct drm_i915_private *i915, enum port port)
>
> static void intel_ddi_encoder_suspend(struct intel_encoder *encoder)
> {
> - struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> - enum phy phy = intel_port_to_phy(i915, encoder->port);
> -
> intel_dp_encoder_suspend(encoder);
> +}
>
> - if (!intel_phy_is_tc(i915, phy))
> - return;
> +static void intel_ddi_tc_encoder_suspend_complete(struct intel_encoder *encoder)
> +{
> + struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
>
> intel_tc_port_flush_work(dig_port);
> }
>
> static void intel_ddi_encoder_shutdown(struct intel_encoder *encoder)
> {
> - struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> - enum phy phy = intel_port_to_phy(i915, encoder->port);
> -
> intel_dp_encoder_shutdown(encoder);
> intel_hdmi_encoder_shutdown(encoder);
> +}
>
> - if (!intel_phy_is_tc(i915, phy))
> - return;
> +static void intel_ddi_tc_encoder_shutdown_complete(struct intel_encoder *encoder)
> +{
> + struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
>
> intel_tc_port_cleanup(dig_port);
> }
> @@ -4908,6 +4904,9 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
> is_legacy ? "legacy" : "non-legacy");
> }
>
> + encoder->suspend_complete = intel_ddi_tc_encoder_suspend_complete;
> + encoder->shutdown_complete = intel_ddi_tc_encoder_shutdown_complete;
> +
> if (intel_tc_port_init(dig_port, is_legacy) < 0)
> goto err;
> }
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 270c4c84a2920..88b2a55d19f21 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -233,13 +233,25 @@ struct intel_encoder {
> * Called during system suspend after all pending requests for the
> * encoder are flushed (for example for DP AUX transactions) and
> * device interrupts are disabled.
> + * All modeset locks are held while the hook is called.
> */
> void (*suspend)(struct intel_encoder *);
> + /*
> + * Called without the modeset locks held after the suspend() hook for
> + * all encoders have been called.
> + */
> + void (*suspend_complete)(struct intel_encoder *encoder);
> /*
> * Called during system reboot/shutdown after all the
> * encoders have been disabled and suspended.
> + * All modeset locks are held while the hook is called.
> */
> void (*shutdown)(struct intel_encoder *encoder);
> + /*
> + * Called without the modeset locks held after the shutdown() hook for
> + * all encoders have been called.
> + */
> + void (*shutdown_complete)(struct intel_encoder *encoder);
> /*
> * Enable/disable the clock to the port.
> */
> diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> index fd198700272b1..705ba65f2ff9a 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -964,6 +964,10 @@ static void intel_suspend_encoders(struct drm_i915_private *dev_priv)
> if (encoder->suspend)
> encoder->suspend(encoder);
> drm_modeset_unlock_all(&dev_priv->drm);
> +
> + for_each_intel_encoder(&dev_priv->drm, encoder)
> + if (encoder->suspend_complete)
> + encoder->suspend_complete(encoder);
> }
>
> static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
> @@ -978,6 +982,10 @@ static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
> if (encoder->shutdown)
> encoder->shutdown(encoder);
> drm_modeset_unlock_all(&dev_priv->drm);
> +
> + for_each_intel_encoder(&dev_priv->drm, encoder)
> + if (encoder->shutdown_complete)
> + encoder->shutdown_complete(encoder);
> }
>
> void i915_driver_shutdown(struct drm_i915_private *i915)
> --
> 2.37.2

--
Ville Syrjälä
Intel