[alsa-devel] [PATCH 12/15] drm/edid: Add API to help find connection type

[Jani Nikula]

On Tue, 01 Dec 2015, "Subhransu S. Prusty" <subhransu.s.prusty at intel.com> wrote:
> To fill the audio infoframe it is required to identify the connection type
> as DP or HDMI. So parse the required bits in ELD to find the connection
> type.
>
> Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty at intel.com>
> Signed-off-by: Vinod Koul <vinod.koul at intel.com>
> Cc: David Airlie <airlied at linux.ie>
> Cc: dri-devel at lists.freedesktop.org
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  include/drm/drm_edid.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 2af9769..c7595a5 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -403,6 +403,16 @@ static inline int drm_eld_size(const uint8_t *eld)
>  	return DRM_ELD_HEADER_BLOCK_SIZE + eld[DRM_ELD_BASELINE_ELD_LEN] * 4;
>  }
>  
> +/**
> + * drm_eld_get_conn_type - Get device type hdmi/dp connected
> + * @eld: pointer to an eld memory structure
> + */
> +static inline int drm_eld_get_conn_type(const uint8_t *eld)
> +{
> +	return (eld[DRM_ELD_SAD_COUNT_CONN_TYPE] & DRM_ELD_CONN_TYPE_MASK) >>
> +		DRM_ELD_CONN_TYPE_SHIFT;
> +}

I'm not sure how much this helps when the caller still needs to
magically know what the return value means...  Indeed the next patch
with /* 0 is hdmi and 1 is DP */ and "conn_type == 0" is a bit ugly.

How about just not shifting the return value, and using
DRM_ELD_CONN_TYPE_HDMI and DRM_ELD_CONN_TYPE_DP in the caller? Bonus
points for referencing those in the kernel-doc above.

BR,
Jani.


> +
>  struct edid *drm_do_get_edid(struct drm_connector *connector,
>  	int (*get_edid_block)(void *data, u8 *buf, unsigned int block,
>  			      size_t len),

-- 
Jani Nikula, Intel Open Source Technology Center