[PATCH v6 07/10] drm: Read DP branch device SW revision

[Jim Bride]

On Wed, Jul 06, 2016 at 02:04:51PM +0300, Mika Kahola wrote:
> SW revision is mandatory field for DisplayPort branch
> devices. This is defined in DPCD register field 0x50A.

Reviewed-by: Jim Bride <jim.bride at linux.intel.com>

> 
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 21 +++++++++++++++++++++
>  include/drm/drm_dp_helper.h     |  2 ++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index cfd75df..19e06a0 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -535,6 +535,27 @@ struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux)
>  EXPORT_SYMBOL(drm_dp_downstream_hw_rev);
>  
>  /**
> + * drm_dp_downstream_sw_rev() - read DP branch device SW revision
> + * @aux: DisplayPort AUX channel
> + *
> + * Returns SW revision on success or negative error code on failure
> + */
> +struct drm_dp_revision drm_dp_downstream_sw_rev(struct drm_dp_aux *aux)
> +{
> +	uint8_t tmp[2];
> +	struct drm_dp_revision rev = { .major = -EINVAL, .minor = -EINVAL };
> +
> +	if (drm_dp_dpcd_read(aux, DP_BRANCH_SW_REV, tmp, 2) != 2)
> +		return rev;
> +
> +	rev.major = tmp[0];
> +	rev.minor = tmp[1];
> +
> +	return rev;
> +}
> +EXPORT_SYMBOL(drm_dp_downstream_sw_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 5f577e4..764a309 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -447,6 +447,7 @@
>  #define DP_BRANCH_OUI			    0x500
>  #define DP_BRANCH_ID                        0x503
>  #define DP_BRANCH_HW_REV                    0x509
> +#define DP_BRANCH_SW_REV                    0x50A
>  
>  #define DP_SET_POWER                        0x600
>  # define DP_SET_POWER_D0                    0x1
> @@ -819,6 +820,7 @@ 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);
> +struct drm_dp_revision drm_dp_downstream_sw_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