Re: [PATCH v8 07/12] drm/i915: Read DP branch device HW revision

[Jim Bride <jim.bride@linux.intel.com>]

On Wed, Aug 17, 2016 at 01:49:43PM +0300, Mika Kahola wrote:
> HW revision is mandatory field for DisplayPort branch
> devices. This is defined in DPCD register field 0x509.
> 
> v2: move drm_dp_ds_revision structure to be part of
>     drm_dp_link structure (Daniel)
> v3: remove dependency to drm_dp_helper but instead parse
>     DPCD and print HW revision info to dmesg (Ville)
> 
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>

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

> ---
>  drivers/gpu/drm/i915/intel_dp.c | 21 +++++++++++++++++++++
>  include/drm/drm_dp_helper.h     |  1 +
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 3dab3bf..9aebdf6 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1419,6 +1419,25 @@ static void intel_dp_print_rates(struct intel_dp *intel_dp)
>  	DRM_DEBUG_KMS("common rates: %s\n", str);
>  }
>  
> +static void intel_dp_print_hw_revision(struct intel_dp *intel_dp)
> +{
> +	uint8_t rev;
> +	int len;
> +
> +	if ((drm_debug & DRM_UT_KMS) == 0)
> +		return;
> +
> +	if (!(intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> +	      DP_DWN_STRM_PORT_PRESENT))
> +		return;
> +
> +	len = drm_dp_dpcd_read(&intel_dp->aux, DP_BRANCH_HW_REV, &rev, 1);
> +	if (len < 0)
> +		return;
> +
> +	DRM_DEBUG_KMS("sink hw revision: %d.%d\n", (rev & 0xf0) >> 4, rev & 0xf);
> +}
> +
>  static int rate_to_index(int find, const int *rates)
>  {
>  	int i = 0;
> @@ -4282,6 +4301,8 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
>  
>  	intel_dp_probe_oui(intel_dp);
>  
> +	intel_dp_print_hw_revision(intel_dp);
> +
>  	intel_dp_configure_mst(intel_dp);
>  
>  	if (intel_dp->is_mst) {
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index faea76b..19ac599 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
> -- 
> 1.9.1
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