[PATCH RFC 21/46] drm: provide a helper for the encoder possible_crtcs mask

[David Herrmann]

Hi

On Thu, Jan 2, 2014 at 10:27 PM, Russell King
<rmk+kernel at arm.linux.org.uk> wrote:
> The encoder possible_crtcs mask identifies which CRTCs can be bound to
> a particular encoder.  Each bit from bit 0 defines an index in the list
> of CRTCs held in the DRM mode_config crtc_list.  Rather than having
> drivers trying to track the position of their CRTCs in the list, expose
> the code which already exists for calculating the appropriate mask bit
> for a CRTC.
>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> ---
>  drivers/gpu/drm/drm_crtc_helper.c |   39 ++++++++++++++++++++++++------------
>  include/drm/drm_crtc_helper.h     |    1 +
>  2 files changed, 27 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
> index 01361aba033b..10708c248196 100644
> --- a/drivers/gpu/drm/drm_crtc_helper.c
> +++ b/drivers/gpu/drm/drm_crtc_helper.c
> @@ -325,6 +325,29 @@ void drm_helper_disable_unused_functions(struct drm_device *dev)
>  EXPORT_SYMBOL(drm_helper_disable_unused_functions);
>
>  /**
> + * drm_helper_crtc_possible_mask - find the mask of a registered CRTC
> + * @crtc: crtc to find mask for
> + *
> + * Given a registered CRTC, return the mask bit of that CRTC for an
> + * encoder's possible_crtcs field.

I think this is a nice cleanup which we could pick up right away. Most
drivers can be simplified by using this. Only the name is misleading,
imo, I'd use something like drm_helper_crtc_to_mask(). Anyhow, not my
call so:

Reviewed-by: David Herrmann <dh.herrmann at gmail.com>

Thanks
David

> + */
> +uint32_t drm_helper_crtc_possible_mask(struct drm_crtc *crtc)
> +{
> +       struct drm_device *dev = crtc->dev;
> +       struct drm_crtc *tmp;
> +       uint32_t crtc_mask = 1;
> +
> +       list_for_each_entry(tmp, &dev->mode_config.crtc_list, head) {
> +               if (tmp == crtc)
> +                       return crtc_mask;
> +               crtc_mask <<= 1;
> +       }
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(drm_helper_crtc_possible_mask);
> +
> +/**
>   * drm_encoder_crtc_ok - can a given crtc drive a given encoder?
>   * @encoder: encoder to test
>   * @crtc: crtc to test
> @@ -334,23 +357,13 @@ EXPORT_SYMBOL(drm_helper_disable_unused_functions);
>  static bool drm_encoder_crtc_ok(struct drm_encoder *encoder,
>                                 struct drm_crtc *crtc)
>  {
> -       struct drm_device *dev;
> -       struct drm_crtc *tmp;
> -       int crtc_mask = 1;
> +       uint32_t crtc_mask;
>
>         WARN(!crtc, "checking null crtc?\n");
>
> -       dev = crtc->dev;
> -
> -       list_for_each_entry(tmp, &dev->mode_config.crtc_list, head) {
> -               if (tmp == crtc)
> -                       break;
> -               crtc_mask <<= 1;
> -       }
> +       crtc_mask = drm_helper_crtc_possible_mask(crtc);
>
> -       if (encoder->possible_crtcs & crtc_mask)
> -               return true;
> -       return false;
> +       return !!(encoder->possible_crtcs & crtc_mask);
>  }
>
>  /*
> diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
> index ef6ad3a8e58e..21b9f47dd88c 100644
> --- a/include/drm/drm_crtc_helper.h
> +++ b/include/drm/drm_crtc_helper.h
> @@ -127,6 +127,7 @@ struct drm_connector_helper_funcs {
>
>  extern int drm_helper_probe_single_connector_modes(struct drm_connector *connector, uint32_t maxX, uint32_t maxY);
>  extern void drm_helper_disable_unused_functions(struct drm_device *dev);
> +extern uint32_t drm_helper_crtc_possible_mask(struct drm_crtc *crtc);
>  extern int drm_crtc_helper_set_config(struct drm_mode_set *set);
>  extern bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
>                                      struct drm_display_mode *mode,
> --
> 1.7.4.4
>
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