Re: [Intel-gfx] [PATCH 1/7] drm/i915/display: Add HDR Capability detection for LSPCON

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 27 Mar 2020, Vipin Anand <vipin.anand@intel.com> wrote:
> From: Uma Shankar <uma.shankar@intel.com>
>
> LSPCON firmware exposes HDR capability through LPCON_CAPABILITIES
> DPCD register. LSPCON implementations capable of supporting
> HDR set HDR_CAPABILITY bit in LSPCON_CAPABILITIES to 1. This patch
> reads the same, detects the HDR capability and adds this to
> intel_lspcon struct.
>
> Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  1 +
>  drivers/gpu/drm/i915/display/intel_lspcon.c   | 32 +++++++++++++++++++
>  2 files changed, 33 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 888ea8a170d1..2f281da6d253 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1333,6 +1333,7 @@ struct intel_lspcon {
>  	bool active;
>  	enum drm_lspcon_mode mode;
>  	enum lspcon_vendor vendor;
> +	bool hdr_supported;
>  };
>  
>  struct intel_digital_port {
> diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c b/drivers/gpu/drm/i915/display/intel_lspcon.c
> index d807c5648c87..2e41ae483a23 100644
> --- a/drivers/gpu/drm/i915/display/intel_lspcon.c
> +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
> @@ -35,6 +35,8 @@
>  #define LSPCON_VENDOR_PARADE_OUI 0x001CF8
>  #define LSPCON_VENDOR_MCA_OUI 0x0060AD
>  
> +#define DPCD_MCA_LSPCON_HDR_STATUS	0x70003
> +
>  /* AUX addresses to write MCA AVI IF */
>  #define LSPCON_MCA_AVI_IF_WRITE_OFFSET 0x5C0
>  #define LSPCON_MCA_AVI_IF_CTRL 0x5DF
> @@ -104,6 +106,31 @@ static bool lspcon_detect_vendor(struct intel_lspcon *lspcon)
>  	return true;
>  }
>  
> +static bool lspcon_detect_hdr_capability(struct intel_lspcon *lspcon)
> +{
> +	struct intel_dp *dp = lspcon_to_intel_dp(lspcon);
> +	u8 hdr_caps;
> +	int ret;
> +
> +	/* Enable HDR for MCA based LSPCON devices */
> +	if (lspcon->vendor == LSPCON_VENDOR_MCA)
> +		ret = drm_dp_dpcd_read(&dp->aux, DPCD_MCA_LSPCON_HDR_STATUS,
> +				       &hdr_caps, 1);
> +	else
> +		return false;
> +
> +	if (ret < 0) {
> +		DRM_DEBUG_KMS("hdr capability detection failed\n");

Debugs etc. should use drm_dbg_kms, errors drm_err, throughout the
series.

> +		lspcon->hdr_supported = false;
> +		return false;
> +	} else if (hdr_caps & 0x1) {
> +		DRM_DEBUG_KMS("lspcon capable of HDR\n");
> +		lspcon->hdr_supported = true;
> +	}
> +
> +	return true;
> +}
> +
>  static enum drm_lspcon_mode lspcon_get_current_mode(struct intel_lspcon *lspcon)
>  {
>  	enum drm_lspcon_mode current_mode;
> @@ -581,6 +608,11 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
>  		return false;
>  	}
>  
> +	if (!lspcon_detect_hdr_capability(lspcon)) {
> +		DRM_ERROR("LSPCON hdr detection failed\n");
> +		return false;

Err what? Breaks all non-MCA LSPCON devices right there. And even if the
detection fails for MCA, no need to prevent non-HDR usage.

BR,
Jani.

> +	}
> +
>  	connector->ycbcr_420_allowed = true;
>  	lspcon->active = true;
>  	DRM_DEBUG_KMS("Success: LSPCON init\n");

-- 
Jani Nikula, Intel Open Source Graphics Center
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