Re: [PATCH v3 3/7] drm/mgag200: Implement connector's get_modes with helper

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 16 May 2022, Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Provide drm_connector_helper_get_modes_from_ddc() to implement the
> connector's get_modes callback. The new helper updates the connector
> from DDC-provided EDID data.

When adding drm core code, please do *not* prefix with "drm/mgag200".

I, and I believe many people, totally ignore changes to a lot of
drivers, while trying to closely follow drm core changes.

Going forward, I'll be slightly changing what the .get_modes hook is
supposed to do, so this feels like a bit of a detour to me. Anyone
picking this up is up for another refactor later on. Oh well.


BR,
Jani.

PS. There's a // comment in there.

>
> v2:
> 	* clear property if EDID is NULL in helper
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
> Tested-by: Jocelyn Falempe <jfalempe@redhat.com>
> ---
>  drivers/gpu/drm/drm_probe_helper.c     | 36 ++++++++++++++++++++++++++
>  drivers/gpu/drm/mgag200/mgag200_mode.c | 17 +++---------
>  include/drm/drm_probe_helper.h         |  2 ++
>  3 files changed, 42 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 682359512996..d77f17867195 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -964,3 +964,39 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
>  	return changed;
>  }
>  EXPORT_SYMBOL(drm_helper_hpd_irq_event);
> +
> +/**
> + * drm_connector_helper_get_modes_from_ddc - Updates the connector's EDID
> + *                                           property from the connector's
> + *                                           DDC channel
> + * @connector: The connector
> + *
> + * Returns:
> + * The number of detected display modes.
> + *
> + * Uses a connector's DDC channel to retrieve EDID data and update the
> + * connector's EDID property and display modes. Drivers can use this
> + * function to implement struct &drm_connector_helper_funcs.get_modes
> + * for connectors with a DDC channel.
> + */
> +int drm_connector_helper_get_modes_from_ddc(struct drm_connector *connector)
> +{
> +	struct edid *edid;
> +	int count = 0;
> +
> +	if (!connector->ddc)
> +		return 0;
> +
> +	edid = drm_get_edid(connector, connector->ddc);
> +
> +	// clears property if EDID is NULL
> +	drm_connector_update_edid_property(connector, edid);
> +
> +	if (edid) {
> +		count = drm_add_edid_modes(connector, edid);
> +		kfree(edid);
> +	}
> +
> +	return count;
> +}
> +EXPORT_SYMBOL(drm_connector_helper_get_modes_from_ddc);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index b227891d01ec..4c0680dd1a78 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -689,26 +689,17 @@ static void mgag200_disable_display(struct mga_device *mdev)
>   * Connector
>   */
>  
> -static int mga_vga_get_modes(struct drm_connector *connector)
> +static int mgag200_vga_connector_helper_get_modes(struct drm_connector *connector)
>  {
>  	struct mga_device *mdev = to_mga_device(connector->dev);
> -	struct mga_connector *mga_connector = to_mga_connector(connector);
> -	struct edid *edid;
> -	int ret = 0;
> +	int ret;
>  
>  	/*
>  	 * Protect access to I/O registers from concurrent modesetting
>  	 * by acquiring the I/O-register lock.
>  	 */
>  	mutex_lock(&mdev->rmmio_lock);
> -
> -	edid = drm_get_edid(connector, &mga_connector->i2c->adapter);
> -	if (edid) {
> -		drm_connector_update_edid_property(connector, edid);
> -		ret = drm_add_edid_modes(connector, edid);
> -		kfree(edid);
> -	}
> -
> +	ret = drm_connector_helper_get_modes_from_ddc(connector);
>  	mutex_unlock(&mdev->rmmio_lock);
>  
>  	return ret;
> @@ -828,7 +819,7 @@ static void mga_connector_destroy(struct drm_connector *connector)
>  }
>  
>  static const struct drm_connector_helper_funcs mga_vga_connector_helper_funcs = {
> -	.get_modes  = mga_vga_get_modes,
> +	.get_modes  = mgag200_vga_connector_helper_get_modes,
>  	.mode_valid = mga_vga_mode_valid,
>  };
>  
> diff --git a/include/drm/drm_probe_helper.h b/include/drm/drm_probe_helper.h
> index 48300aa6ca71..c80cab7a53b7 100644
> --- a/include/drm/drm_probe_helper.h
> +++ b/include/drm/drm_probe_helper.h
> @@ -26,4 +26,6 @@ void drm_kms_helper_poll_disable(struct drm_device *dev);
>  void drm_kms_helper_poll_enable(struct drm_device *dev);
>  bool drm_kms_helper_is_poll_worker(void);
>  
> +int drm_connector_helper_get_modes_from_ddc(struct drm_connector *connector);
> +
>  #endif

-- 
Jani Nikula, Intel Open Source Graphics Center