On Wed-27-04-2022 03:31 am, Navare, Manasi wrote:

On Mon, Apr 25, 2022 at 12:16:11PM +0530, Bhanuprakash Modem wrote:

...

Modern display hardware is capable of supporting variable refresh rates. This patch introduces helpers to attach and set "vrr_enabled" property on the crtc to allow userspace to query VRR enabled status on that crtc.

Atomic drivers should attach this property to crtcs those are capable of driving variable refresh rates using drm_mode_crtc_attach_vrr_enabled_property().

The value should be updated based on driver and hardware capability by using drm_mode_crtc_set_vrr_enabled_property().

V2: Use property flag as atomic

We already have userspace making us of the CRTC vrr_enabled property to enable VRR for the CRTC like in case of full screen gaming.

This can already be done through: drm_atomic_crtc_set_property call. Why do we need additonal helpers for setting the same per CRTC property?

Thanks for the Review, Manasi.

Yeah, I just realized that we are attaching "vrr_enabled" as part of crtc_init()

drm_crtc_init_with_planes() --> __drm_crtc_init_with_planes() --> drm_object_attach_property(vrr_enabled);

I'll drop the drm_mode_crtc_attach_vrr_enabled_property() helper.

This is a default CRTC property so it will be created annd attached for CRTC as per the DRM doc: "VRR_ENABLED":

•  Default &drm_crtc boolean property that notifies the driver that the
  

•  content on the CRTC is suitable for variable refresh rate presentation.
  

•  The driver will take this property as a hint to enable variable
  

•  refresh rate support if the receiver supports it, ie. if the
  

•  "vrr_capable" property is true on the &drm_connector object. The
  

•  vertical front porch duration will be extended until page-flip or
  

•  timeout when enabled.
  
  

Then we can use the atomic_crtc_set/get_property helpers to set it Am I missing some other use case here?

My intention is to set/clear "VRR_ENABLED" prop based on the driver and hardware capabilities. And user can request anytime to get the status of VRR on that CRTC.

Example: Consider we have an Non-VRR panel is connected, but driver supports VRR (hence vrr_capable = 0) * Request from user-space to enable the VRR on CRTC. * Driver should take the decision to set/clear the "VRR_ENABLED". * Request from use-space to read back the "VRR_ENABLED". It must be 0, since "vrr_capable" is 0.

Without this series, in above scenario I am getting "VRR_ENABLED" as 1 which is not true.

IGT to validate the same: https://patchwork.freedesktop.org/series/100539/

I think, still we need a helper to set/clear the prop drm_mode_crtc_set_vrr_enabled_property(). I am not sure that we can use atomic_crtc_set/get_property helpers here, as these helpers are used by atomic_ioctls only.

- Bhanu

Manasi

...

Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Nicholas Kazlauskas nicholas.kazlauskas@amd.com Cc: Manasi Navare manasi.d.navare@intel.com Cc: Harry Wentland harry.wentland@amd.com Signed-off-by: Bhanuprakash Modem bhanuprakash.modem@intel.com

---

drivers/gpu/drm/drm_crtc.c | 44 +++++++++++++++++++++++++++++++ drivers/gpu/drm/drm_mode_config.c | 2 +- include/drm/drm_crtc.h | 4 +++ 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 26a77a735905..95b4a0c7ecb3 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -883,3 +883,47 @@ int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc, return 0; } EXPORT_SYMBOL(drm_crtc_create_scaling_filter_property);

+/**

• • drm_mode_crtc_attach_vrr_enabled_property - attaches the vrr_enabled property
• • @crtc: drm CRTC to attach the vrr_enabled property on.
• • This is used by atomic drivers to add support for querying
• • VRR enabled status for a crtc.
• */

+void drm_mode_crtc_attach_vrr_enabled_property(struct drm_crtc *crtc) +{

• struct drm_device *dev = crtc->dev;
• struct drm_mode_config *config = &dev->mode_config;
• if (!config->prop_vrr_enabled)

• return;
  

• drm_object_attach_property(&crtc->base,

• 		   config->prop_vrr_enabled,
  

• 		   0);
  

+} +EXPORT_SYMBOL(drm_mode_crtc_attach_vrr_enabled_property);

+/**

• • drm_mode_crtc_set_vrr_enabled_property - sets the vrr enabled property for
• • a crtc.
• • @crtc: drm CRTC
• • @vrr_enabled: True to enable the VRR on CRTC
• • Should be used by atomic drivers to update the VRR enabled status on a CRTC
• */

+void drm_mode_crtc_set_vrr_enabled_property(struct drm_crtc *crtc,

• 			    bool vrr_enabled)
  

+{

• struct drm_device *dev = crtc->dev;
• struct drm_mode_config *config = &dev->mode_config;
• if (!config->prop_vrr_enabled)

• return;
  

• drm_object_property_set_value(&crtc->base,

• 		      config->prop_vrr_enabled,
  

• 		      vrr_enabled);
  

+} +EXPORT_SYMBOL(drm_mode_crtc_set_vrr_enabled_property); diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 37b4b9f0e468..b7cde73d5586 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -323,7 +323,7 @@ static int drm_mode_create_standard_properties(struct drm_device *dev) return -ENOMEM; dev->mode_config.prop_mode_id = prop;

• prop = drm_property_create_bool(dev, 0,

• prop = drm_property_create_bool(dev, DRM_MODE_PROP_ATOMIC, "VRR_ENABLED"); if (!prop) return -ENOMEM;

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index a70baea0636c..bde657cb0f9e 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -1333,4 +1333,8 @@ static inline struct drm_crtc *drm_crtc_find(struct drm_device *dev, int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc, unsigned int supported_filters);

+void drm_mode_crtc_attach_vrr_enabled_property(struct drm_crtc *crtc); +void drm_mode_crtc_set_vrr_enabled_property(struct drm_crtc *crtc,

• 			    bool vrr_enabled);
  

• #endif /* __DRM_CRTC_H__ */

-- 2.35.1