Re: [PATCH] drm/dp: move intel_dp_vsc_sdp_pack() to generic helper

Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> · Wed, 14 Feb 2024 10:08:38 -0800

On 2/14/2024 10:02 AM, Ville Syrjälä wrote:
On Wed, Feb 14, 2024 at 09:17:34AM -0800, Abhinav Kumar wrote:


On 2/14/2024 12:15 AM, Dmitry Baryshkov wrote:
On Wed, 14 Feb 2024 at 01:45, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:

intel_dp_vsc_sdp_pack() can be re-used by other DRM drivers as well.
Lets move this to drm_dp_helper to achieve this.

Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>

My preference would be to have packing functions in
drivers/video/hdmi.c, as we already have
hdmi_audio_infoframe_pack_for_dp() there.


My preference is drm_dp_helper because it already has some VSC SDP stuff
and after discussion with Ville on IRC, I decided to post it this way.

hdmi_audio_infoframe_pack_for_dp() is an exception from my PoV as the
hdmi audio infoframe fields were re-used and packed into a DP SDP
thereby re-using the existing struct hdmi_audio_infoframe .

This is not like that. Here we pack from struct drm_dp_vsc_sdp to struct
dp_sdp both of which had prior usages already in this file.

So it all adds up and makes sense to me to be in this file.

I will let the other DRM core maintainers comment on this.

Ville, Jani?

Yeah, I'm not sure bloating the (poorly named) hdmi.c with all
SDP stuff is a great idea. Since other related stuff already
lives in the drm_dp_helper.c that seems reasonable to me at this
time. And if we get a decent amount of this then probably all
DP SDP stuff should be extracted into its own file.


Yes, thanks.

There are of course a few overlaps here andthere (the audio SDP
I guess, and the CTA infoframe SDP). But I'm not sure that actually
needs any SDP specific stuff in hdmi.c, or could we just let hdmi.c
deal with the actual CTA-861 stuff and then have the DP SDP code
wrap that up in its own thing externally? Dunno, haven't really
looked at the details.


Thats a good way to look at it. this packing is from DP spec and not CTA 
so makes more sense to be in this file.

In that case, R-b?


---
   drivers/gpu/drm/display/drm_dp_helper.c | 78 +++++++++++++++++++++++++
   drivers/gpu/drm/i915/display/intel_dp.c | 73 +----------------------
   include/drm/display/drm_dp_helper.h     |  3 +
   3 files changed, 84 insertions(+), 70 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index b1ca3a1100da..066cfbbf7a91 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2916,6 +2916,84 @@ void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
   }
   EXPORT_SYMBOL(drm_dp_vsc_sdp_log);

+/**
+ * drm_dp_vsc_sdp_pack() - pack a given vsc sdp into generic dp_sdp
+ * @vsc: vsc sdp initialized according to its purpose as defined in
+ *       table 2-118 - table 2-120 in DP 1.4a specification
+ * @sdp: valid handle to the generic dp_sdp which will be packed
+ * @size: valid size of the passed sdp handle
+ *
+ * Returns length of sdp on success and error code on failure
+ */
+ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
+                           struct dp_sdp *sdp, size_t size)

I know that you are just moving the function. Maybe there can be
patch#2, which drops the size argument? The struct dp_sdp already has
a defined size. The i915 driver just passes sizeof(sdp), which is more
or less useless.


Yes this is a valid point, I also noticed this. I can post it on top of
this once we get an agreement and ack on this patch first.

+{
+       size_t length = sizeof(struct dp_sdp);
+
+       if (size < length)
+               return -ENOSPC;
+
+       memset(sdp, 0, size);
+
+       /*
+        * Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
+        * VSC SDP Header Bytes
+        */
+       sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
+       sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
+       sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
+       sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
+
+       if (vsc->revision == 0x6) {
+               sdp->db[0] = 1;
+               sdp->db[3] = 1;
+       }
+
+       /*
+        * Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
+        * Format as per DP 1.4a spec and DP 2.0 respectively.
+        */
+       if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
+               goto out;
+
+       /* VSC SDP Payload for DB16 through DB18 */
+       /* Pixel Encoding and Colorimetry Formats  */
+       sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
+       sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
+
+       switch (vsc->bpc) {
+       case 6:
+               /* 6bpc: 0x0 */
+               break;
+       case 8:
+               sdp->db[17] = 0x1; /* DB17[3:0] */
+               break;
+       case 10:
+               sdp->db[17] = 0x2;
+               break;
+       case 12:
+               sdp->db[17] = 0x3;
+               break;
+       case 16:
+               sdp->db[17] = 0x4;
+               break;
+       default:
+               WARN(1, "Missing case %d\n", vsc->bpc);
+               return -EINVAL;
+       }
+
+       /* Dynamic Range and Component Bit Depth */
+       if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
+               sdp->db[17] |= 0x80;  /* DB17[7] */
+
+       /* Content Type */
+       sdp->db[18] = vsc->content_type & 0x7;
+
+out:
+       return length;
+}
+EXPORT_SYMBOL(drm_dp_vsc_sdp_pack);
+
   /**
    * drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
    * @dpcd: DisplayPort configuration data
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index f5ef95da5534..e94db51aeeb7 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4110,73 +4110,6 @@ intel_dp_needs_vsc_sdp(const struct intel_crtc_state *crtc_state,
          return false;
   }

-static ssize_t intel_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
-                                    struct dp_sdp *sdp, size_t size)
-{
-       size_t length = sizeof(struct dp_sdp);
-
-       if (size < length)
-               return -ENOSPC;
-
-       memset(sdp, 0, size);
-
-       /*
-        * Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
-        * VSC SDP Header Bytes
-        */
-       sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
-       sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
-       sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
-       sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
-
-       if (vsc->revision == 0x6) {
-               sdp->db[0] = 1;
-               sdp->db[3] = 1;
-       }
-
-       /*
-        * Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
-        * Format as per DP 1.4a spec and DP 2.0 respectively.
-        */
-       if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
-               goto out;
-
-       /* VSC SDP Payload for DB16 through DB18 */
-       /* Pixel Encoding and Colorimetry Formats  */
-       sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
-       sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
-
-       switch (vsc->bpc) {
-       case 6:
-               /* 6bpc: 0x0 */
-               break;
-       case 8:
-               sdp->db[17] = 0x1; /* DB17[3:0] */
-               break;
-       case 10:
-               sdp->db[17] = 0x2;
-               break;
-       case 12:
-               sdp->db[17] = 0x3;
-               break;
-       case 16:
-               sdp->db[17] = 0x4;
-               break;
-       default:
-               MISSING_CASE(vsc->bpc);
-               break;
-       }
-       /* Dynamic Range and Component Bit Depth */
-       if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
-               sdp->db[17] |= 0x80;  /* DB17[7] */
-
-       /* Content Type */
-       sdp->db[18] = vsc->content_type & 0x7;
-
-out:
-       return length;
-}
-
   static ssize_t
   intel_dp_hdr_metadata_infoframe_sdp_pack(struct drm_i915_private *i915,
                                           const struct hdmi_drm_infoframe *drm_infoframe,
@@ -4269,8 +4202,8 @@ static void intel_write_dp_sdp(struct intel_encoder *encoder,

          switch (type) {
          case DP_SDP_VSC:
-               len = intel_dp_vsc_sdp_pack(&crtc_state->infoframes.vsc, &sdp,
-                                           sizeof(sdp));
+               len = drm_dp_vsc_sdp_pack(&crtc_state->infoframes.vsc, &sdp,
+                                         sizeof(sdp));
                  break;
          case HDMI_PACKET_TYPE_GAMUT_METADATA:
                  len = intel_dp_hdr_metadata_infoframe_sdp_pack(dev_priv,
@@ -4297,7 +4230,7 @@ void intel_write_dp_vsc_sdp(struct intel_encoder *encoder,
          struct dp_sdp sdp = {};
          ssize_t len;

-       len = intel_dp_vsc_sdp_pack(vsc, &sdp, sizeof(sdp));
+       len = drm_dp_vsc_sdp_pack(vsc, &sdp, sizeof(sdp));

          if (drm_WARN_ON(&dev_priv->drm, len < 0))
                  return;
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 863b2e7add29..f8db34a2f7a5 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -813,4 +813,7 @@ int drm_dp_bw_overhead(int lane_count, int hactive,
                         int bpp_x16, unsigned long flags);
   int drm_dp_bw_channel_coding_efficiency(bool is_uhbr);

+ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
+                           struct dp_sdp *sdp, size_t size);
+
   #endif /* _DRM_DP_HELPER_H_ */
--
2.34.1










