[PATCH v6 06/10] drm: Read DP branch device HW revision

[Daniel Vetter]

On Wed, Jul 06, 2016 at 02:04:50PM +0300, Mika Kahola wrote:
> HW revision is mandatory field for DisplayPort branch
> devices. This is defined in DPCD register field 0x509.
> 
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 21 +++++++++++++++++++++
>  include/drm/drm_dp_helper.h     |  7 +++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 4003464..cfd75df 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -514,6 +514,27 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
>  
>  /**
> + * drm_dp_downstream_hw_rev() - read DP branch device HW revision
> + * @aux: DisplayPort AUX channel
> + *
> + * Returns HW revision on succes or negative error code on failure
> + */
> +struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux)
> +{
> +	uint8_t tmp;
> +	struct drm_dp_revision rev = { .major = -EINVAL, .minor = -EINVAL };
> +
> +	if (drm_dp_dpcd_read(aux, DP_BRANCH_HW_REV, &tmp, 1) != 1)
> +		return rev;
> +
> +	rev.major = (tmp & 0xf0) >> 4;
> +	rev.minor = tmp & 0xf;
> +
> +	return rev;
> +}
> +EXPORT_SYMBOL(drm_dp_downstream_hw_rev);
> +
> +/**
>   * drm_dp_downstream_id() - identify branch device
>   * @aux: DisplayPort AUX channel
>   *
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 8264d54..5f577e4 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -446,6 +446,7 @@
>  #define DP_SINK_OUI			    0x400
>  #define DP_BRANCH_OUI			    0x500
>  #define DP_BRANCH_ID                        0x503
> +#define DP_BRANCH_HW_REV                    0x509
>  
>  #define DP_SET_POWER                        0x600
>  # define DP_SET_POWER_D0                    0x1
> @@ -803,6 +804,11 @@ struct drm_dp_link {
>  	unsigned long capabilities;
>  };
>  
> +struct drm_dp_revision {
> +       int major;
> +       int minor;
> +};

Atm we have two styles of helpers:
- The ones that put decoded values into struct drm_dp_link
- A pile of functions that return individual values.

This seems to add a third one. I guess it'd be better to just move
everything over to putting parsed values into drm_dp_link and fill that
out for everything ...
-Daniel

> +
>  int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
> @@ -812,6 +818,7 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
>  			      const u8 port_cap[4]);
>  int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
> +struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux);
>  
>  void drm_dp_aux_init(struct drm_dp_aux *aux);
>  int drm_dp_aux_register(struct drm_dp_aux *aux);
> -- 
> 1.9.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch