Re: [Intel-gfx] [PATCH 2/3] drm/i915/display/: Add Read/Write support for Adaptive Sync SDP

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

On Thu, 23 Nov 2023, Mitul Golani <mitulkumar.ajitkumar.golani@intel.com> wrote:
> Add the necessary structures and functions to handle reading and
> unpacking Adaptive Sync Secondary Data Packets. Also add support
> to write and pack AS SDP.
>
> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |   1 +
>  drivers/gpu/drm/i915/display/intel_dp.c       | 118 +++++++++++++++++-
>  2 files changed, 114 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 9a44350ba05d..7d87923f63af 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1325,6 +1325,7 @@ struct intel_crtc_state {
>  		union hdmi_infoframe hdmi;
>  		union hdmi_infoframe drm;
>  		struct drm_dp_vsc_sdp vsc;
> +		struct drm_dp_as_sdp  async;
>  	} infoframes;
>  
>  	u8 eld[MAX_ELD_BYTES];
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 1422c2370269..39624746d612 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -94,6 +94,8 @@
>  #define INTEL_DP_RESOLUTION_STANDARD	(2 << INTEL_DP_RESOLUTION_SHIFT_MASK)
>  #define INTEL_DP_RESOLUTION_FAILSAFE	(3 << INTEL_DP_RESOLUTION_SHIFT_MASK)
>  
> +#define AS_SDP_ENABLE					REG_BIT(2)
> +#define AS_SDP_OP_MODE					REG_GENMASK(1, 0)

REG_BIT and REG_GENMASK are for i915_reg_t.

Moreover, these are stuff inside the SDP, so these should be somewhere
near struct drm_dp_as_sdp definition, otherwise people are just going to
duplicate them.

>  
>  /* Constants for DP DSC configurations */
>  static const u8 valid_dsc_bpp[] = {6, 8, 10, 12, 15};
> @@ -4113,6 +4115,42 @@ intel_dp_needs_vsc_sdp(const struct intel_crtc_state *crtc_state,
>  	return false;
>  }
>  
> +static ssize_t intel_dp_as_sdp_pack(const struct drm_dp_as_sdp *async,

Again, please don't use async for adaptive sync.

> +				    struct dp_sdp *sdp, size_t size)
> +{
> +	size_t length = sizeof(struct dp_sdp);
> +
> +	if (size < length)
> +		return -ENOSPC;
> +
> +	memset(sdp, 0, size);
> +
> +	/* Prepare AS (Adaptive Sync) VSC Header */
> +	sdp->sdp_header.HB0 = 0;
> +	sdp->sdp_header.HB1 = async->sdp_type;
> +	sdp->sdp_header.HB2 = 0x02;
> +	sdp->sdp_header.HB3 = async->length;
> +
> +	/* Fill AS (Adaptive Sync) SDP Payload */
> +	if ((sdp->db[0] & 0x03) == 0) {
> +		sdp->db[3] = 0;
> +		sdp->db[4] &= 0xFC;
> +	}
> +
> +	sdp->db[1] = async->vmin & 0xFF;
> +	sdp->db[2] = (async->vmin >> 8) & 0xF;
> +	sdp->db[17] = (async->vmin >> 8) & 0xFF;
> +	sdp->db[18] = async->vmax & 0xFF;
> +	sdp->db[19] = (async->vmax >> 8) & 0xFF;
> +	sdp->db[20] = async->target_rr & 0xFF;
> +	sdp->db[21] = (async->target_rr >> 8) & 0xFF;
> +	sdp->db[22] = async->duration_incr_ms;
> +	sdp->db[23] = async->duration_decr_ms;
> +	sdp->db[24] = async->operation_mode;
> +
> +	return length;
> +}
> +
>  static ssize_t intel_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
>  				     struct dp_sdp *sdp, size_t size)
>  {
> @@ -4280,6 +4318,10 @@ static void intel_write_dp_sdp(struct intel_encoder *encoder,
>  							       &crtc_state->infoframes.drm.drm,
>  							       &sdp, sizeof(sdp));
>  		break;
> +	case DP_SDP_ADAPTIVE_SYNC:
> +		len = intel_dp_as_sdp_pack(&crtc_state->infoframes.async, &sdp,
> +					   sizeof(sdp));
> +		break;
>  	default:
>  		MISSING_CASE(type);
>  		return;
> @@ -4342,6 +4384,44 @@ void intel_dp_set_infoframes(struct intel_encoder *encoder,
>  	intel_write_dp_sdp(encoder, crtc_state, HDMI_PACKET_TYPE_GAMUT_METADATA);
>  }
>  
> +/*
> + * This function is to unpack AS SDP Packet
> + */

What value does this comment add? It says exactly the same thing as the
function name.

> +static
> +int intel_dp_as_sdp_unpack(struct drm_dp_as_sdp *async,
> +			   const void *buffer, size_t size)
> +{
> +	const struct dp_sdp *sdp = buffer;
> +
> +	if (size < sizeof(struct dp_sdp))
> +		return -EINVAL;
> +
> +	memset(async, 0, sizeof(*async));
> +
> +	if (sdp->sdp_header.HB0 != 0)
> +		return -EINVAL;
> +
> +	if (sdp->sdp_header.HB1 != DP_SDP_ADAPTIVE_SYNC)
> +		return -EINVAL;
> +
> +	if (sdp->sdp_header.HB2 != 0x02)
> +		return -EINVAL;
> +
> +	if ((sdp->sdp_header.HB3 & 0x3F) != 9)
> +		return -EINVAL;
> +
> +	if (sdp->db[0] != (AS_SDP_ENABLE | AS_SDP_OP_MODE))
> +		return -EINVAL;
> +
> +	async->vmin = ((u64)sdp->db[2] << 32) | (u64)sdp->db[1];
> +	async->vmax = 0;
> +	async->target_rr = 0;
> +	async->duration_incr_ms = 0;
> +	async->duration_decr_ms = 0;
> +
> +	return 0;
> +}
> +
>  static int intel_dp_vsc_sdp_unpack(struct drm_dp_vsc_sdp *vsc,
>  				   const void *buffer, size_t size)
>  {
> @@ -4412,12 +4492,35 @@ static int intel_dp_vsc_sdp_unpack(struct drm_dp_vsc_sdp *vsc,
>  	return 0;
>  }
>  
> +/*
> + * This function to read registers to fetch packets
> + */

Unnecessary comment.

> +static int
> +intel_read_dp_as_metadata_infoframe_sdp(struct intel_encoder *encoder,
> +					struct intel_crtc_state *crtc_state,
> +					struct drm_dp_as_sdp *async)
> +{
> +	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	unsigned int type = DP_SDP_ADAPTIVE_SYNC;
> +	struct dp_sdp sdp = {};
> +	int ret;
> +
> +	dig_port->read_infoframe(encoder, crtc_state, type, &sdp,
> +				 sizeof(sdp));
> +
> +	ret = intel_dp_as_sdp_unpack(async, &sdp, sizeof(sdp));
> +	if (ret)
> +		drm_dbg_kms(&dev_priv->drm, "Failed to unpack DP AS SDP\n");
> +
> +	return ret;
> +}
> +
>  static int
>  intel_dp_hdr_metadata_infoframe_sdp_unpack(struct hdmi_drm_infoframe *drm_infoframe,
>  					   const void *buffer, size_t size)
>  {
>  	int ret;
> -

Unrelated change.

>  	const struct dp_sdp *sdp = buffer;
>  
>  	if (size < sizeof(struct dp_sdp))
> @@ -4484,9 +4587,10 @@ static void intel_read_dp_vsc_sdp(struct intel_encoder *encoder,
>  		drm_dbg_kms(&dev_priv->drm, "Failed to unpack DP VSC SDP\n");
>  }
>  
> -static void intel_read_dp_hdr_metadata_infoframe_sdp(struct intel_encoder *encoder,
> -						     struct intel_crtc_state *crtc_state,
> -						     struct hdmi_drm_infoframe *drm_infoframe)
> +static void
> +intel_read_dp_hdr_metadata_infoframe_sdp(struct intel_encoder *encoder,
> +					 struct intel_crtc_state *crtc_state,
> +					 struct hdmi_drm_infoframe *drm_infoframe)

Unrelated change.

>  {
>  	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> @@ -4495,7 +4599,7 @@ static void intel_read_dp_hdr_metadata_infoframe_sdp(struct intel_encoder *encod
>  	int ret;
>  
>  	if ((crtc_state->infoframes.enable &
> -	    intel_hdmi_infoframe_enable(type)) == 0)
> +	     intel_hdmi_infoframe_enable(type)) == 0)

Unrelated change.

>  		return;
>  
>  	dig_port->read_infoframe(encoder, crtc_state, type, &sdp,
> @@ -4522,6 +4626,10 @@ void intel_read_dp_sdp(struct intel_encoder *encoder,
>  		intel_read_dp_hdr_metadata_infoframe_sdp(encoder, crtc_state,
>  							 &crtc_state->infoframes.drm.drm);
>  		break;
> +	case DP_SDP_ADAPTIVE_SYNC:
> +		intel_read_dp_as_metadata_infoframe_sdp(encoder, crtc_state,
> +							&crtc_state->infoframes.async);
> +	break;

Wrong indent, please run checkpatch before posting.

>  	default:
>  		MISSING_CASE(type);
>  		break;

-- 
Jani Nikula, Intel