On Fri, Apr 28, 2017 at 02:47:11PM +0100, Jose Abreu wrote:
> Some crtc's may have restrictions in the mode they can display. In
> this patch a new callback (crtc->mode_valid()) is introduced that
> is called at the same stage of connector->mode_valid() callback.
> 
> This shall be implemented if the crtc has some sort of restriction
> so that we don't probe modes that will fail in the commit() stage.
> For example: A given crtc may be responsible to set a clock value.
> If the clock can not produce all the values for the available
> modes then this callback can be used to restrict the number of
> probbed modes to only the ones that can be displayed.
> 
> If the crtc does not implement the callback then the behaviour will
> remain the same. Also, for a given set of crtcs that can be bound to
> the connector, if at least one can display the mode then the mode
> will be probbed.
> 
> Signed-off-by: Jose Abreu <joab...@synopsys.com>
> Cc: Carlos Palminha <palmi...@synopsys.com>
> Cc: Alexey Brodkin <abrod...@synopsys.com>
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
> Cc: Dave Airlie <airl...@linux.ie>
> Cc: Andrzej Hajda <a.ha...@samsung.com>
> ---
> 
> Changes v1->v2:
>       - Correct indentation
>       - Change function name to drm_validate_connector
>       - Move connnector->mode_valid() to new function
>       - Change crtc->mode_valid() "mode" field to const
>       - Code reogarnization
>       - Return earlier if crtc accepts mode
> 
>  drivers/gpu/drm/drm_probe_helper.c       | 50 
> ++++++++++++++++++++++++++++++--
>  include/drm/drm_modeset_helper_vtables.h | 26 +++++++++++++++++
>  2 files changed, 74 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_probe_helper.c 
> b/drivers/gpu/drm/drm_probe_helper.c
> index 1b0c14a..0741f36 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -80,6 +80,52 @@
>       return MODE_OK;
>  }
>  
> +static enum drm_mode_status
> +drm_mode_validate_connector(struct drm_connector *connector,
> +                         struct drm_display_mode *mode)
> +{
> +     const struct drm_connector_helper_funcs *connector_funcs =
> +             connector->helper_private;
> +     struct drm_device *dev = connector->dev;
> +     uint32_t *ids = connector->encoder_ids;
> +     enum drm_mode_status ret = MODE_OK;
> +     unsigned int i;
> +
> +     /* Step 1: Validate against connector */
> +     if (connector_funcs->mode_valid)
> +             ret = connector_funcs->mode_valid(connector, mode);
> +
> +     if (ret != MODE_OK)
> +             return ret;
> +
> +     /* Step 2: Validate against crtc's */
> +     for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> +             struct drm_encoder *encoder = drm_encoder_find(dev, ids[i]);
> +             struct drm_crtc *crtc;
> +
> +             if (!encoder)
> +                     continue;
> +
> +             drm_for_each_crtc(crtc, dev) {
> +                     const struct drm_crtc_helper_funcs *crtc_funcs;
> +
> +                     if (!drm_encoder_crtc_ok(encoder, crtc))
> +                             continue;
> +
> +                     crtc_funcs = crtc->helper_private;
> +                     if (!crtc_funcs || !crtc_funcs->mode_valid)
> +                             return MODE_OK; /* crtc accepts everything */
> +
> +                     ret = crtc_funcs->mode_valid(crtc, mode);
> +                     if (ret == MODE_OK)
> +                             return ret;

> +             }
> +     }
> +
> +     /* NOTE: If no crtc or encoder is found then we return MODE_OK */

I think this comment is misleading because here ret is not alwyas MODE_OK.
It will be the return value from crtc_func->mode_valid which could also
be MODE_NOCLOCK

Manasi

> +     return ret;
> +}
> +
>  static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
>  {
>       struct drm_cmdline_mode *cmdline_mode;
> @@ -428,8 +474,8 @@ int drm_helper_probe_single_connector_modes(struct 
> drm_connector *connector,
>               if (mode->status == MODE_OK)
>                       mode->status = drm_mode_validate_flag(mode, mode_flags);
>  
> -             if (mode->status == MODE_OK && connector_funcs->mode_valid)
> -                     mode->status = connector_funcs->mode_valid(connector,
> +             if (mode->status == MODE_OK)
> +                     mode->status = drm_mode_validate_connector(connector,
>                                                                  mode);
>       }
>  
> diff --git a/include/drm/drm_modeset_helper_vtables.h 
> b/include/drm/drm_modeset_helper_vtables.h
> index c01c328..ecb055c 100644
> --- a/include/drm/drm_modeset_helper_vtables.h
> +++ b/include/drm/drm_modeset_helper_vtables.h
> @@ -106,6 +106,32 @@ struct drm_crtc_helper_funcs {
>       void (*commit)(struct drm_crtc *crtc);
>  
>       /**
> +      * @mode_valid:
> +      *
> +      * This callback should be implemented if the crtc has some sort of
> +      * restriction in the modes it can display. For example, a given crtc
> +      * may be responsible to set a clock value. If the clock can not
> +      * produce all the values for the available modes then this callback
> +      * can be used to restrict the number of probbed modes to only the ones
> +      * that can be displayed.
> +      *
> +      * This is directly called at the same stage of connector->mode_valid
> +      * callback.
> +      *
> +      * NOTE:
> +      *
> +      * For a given set of crtc's in a drm_device, if at least one does not
> +      * have the mode_valid callback, or, at least one returns MODE_OK then
> +      * the mode will be probbed.
> +      *
> +      * RETURNS:
> +      *
> +      * drm_mode_status Enum
> +      */
> +     enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
> +                                        const struct drm_display_mode *mode);
> +
> +     /**
>        * @mode_fixup:
>        *
>        * This callback is used to validate a mode. The parameter mode is the
> -- 
> 1.9.1
> 
> 
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