On Fri, 2020-09-04 at 14:53 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Deal with more cases in drm_dp_downstream_max_bpc():
> - DPCD 1.0 -> assume 8bpc for non-DP
> - DPCD 1.1+ DP (or DP++ with DP sink) -> allow anything
> - DPCD 1.1+ TMDS -> check the caps, assume 8bpc if the value is crap
> - anything else -> assume 8bpc
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 69 +++++++++++--------
> .../drm/i915/display/intel_display_debugfs.c | 3 +-
> drivers/gpu/drm/i915/display/intel_dp.c | 2 +-
> include/drm/drm_dp_helper.h | 10 ++-
> 4 files changed, 51 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
> b/drivers/gpu/drm/drm_dp_helper.c
> index 0fcb94f7dbe5..ab87209c25d8 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -653,36 +653,44 @@ int drm_dp_downstream_max_clock(const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> EXPORT_SYMBOL(drm_dp_downstream_max_clock);
>
> /**
> - * drm_dp_downstream_max_bpc() - extract branch device max
> - * bits per component
> - * @dpcd: DisplayPort configuration data
> - * @port_cap: port capabilities
> - *
> - * See also:
> - * drm_dp_read_downstream_info()
> - * drm_dp_downstream_max_clock()
> - *
> - * Returns: Max bpc on success or 0 if max bpc not defined
> - */
> + * drm_dp_downstream_max_bpc() - extract downstream facing port max
> + * bits per component
> + * @dpcd: DisplayPort configuration data
> + * @port_cap: downstream facing port capabilities
> + * @edid: EDID
> + *
> + * Returns max bpc on success or 0 if max bpc not defined
> + */
> int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> - const u8 port_cap[4])
> + const u8 port_cap[4],
> + const struct edid *edid)
> {
> - int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
> - bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> - DP_DETAILED_CAP_INFO_AVAILABLE;
> - int bpc;
> -
> - if (!detailed_cap_info)
I don't think we can drop this check. There's a somewhat surprising blurb
about downstream port caps in the DP 2.0 spec (section 5.3.3.1):
In addition, the adapter shall set the Detailed Capabilities Info registers
(DPCD Addresses 00080h through 0008Fh) to show all the downstream types,
including DFP 0. Either one or four bytes are used, per DFP type
indication. Therefore, up to 16 (with 1-byte descriptor) or four (with 4-
byte descriptor) DFP capabilities can be stored.
I've never once actually seen a sink do this, but this does mean it's
technically possible tthat if we don't check the detailed caps bit then we
might end up reading another port's DFP type instead of max_bpc info. Note
though that we can make the assumption the four byte version of the field is
used for DP 1.4+
> + if (!drm_dp_is_branch(dpcd))
> return 0;
>
> - switch (type) {
> - case DP_DS_PORT_TYPE_VGA:
> - case DP_DS_PORT_TYPE_DVI:
> - case DP_DS_PORT_TYPE_HDMI:
> + if (dpcd[DP_DPCD_REV] < 0x11) {
> + switch (dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> DP_DWN_STRM_PORT_TYPE_MASK) {
> + case DP_DWN_STRM_PORT_TYPE_DP:
> + return 0;
> + default:
> + return 8;
> + }
> + }
> +
> + switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
> + case DP_DS_PORT_TYPE_DP:
> + return 0;
> case DP_DS_PORT_TYPE_DP_DUALMODE:
> - bpc = port_cap[2] & DP_DS_MAX_BPC_MASK;
> + if (is_edid_digital_input_dp(edid))
> + return 0;
> + fallthrough;
> + case DP_DS_PORT_TYPE_HDMI:
> + case DP_DS_PORT_TYPE_DVI:
> + case DP_DS_PORT_TYPE_VGA:
> + if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
> + return 8;
>
> - switch (bpc) {
> + switch (port_cap[2] & DP_DS_MAX_BPC_MASK) {
> case DP_DS_8BPC:
> return 8;
> case DP_DS_10BPC:
> @@ -691,10 +699,12 @@ int drm_dp_downstream_max_bpc(const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> return 12;
> case DP_DS_16BPC:
> return 16;
> + default:
> + return 8;
> }
> - fallthrough;
> + break;
> default:
> - return 0;
> + return 8;
> }
> }
> EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
> @@ -717,12 +727,15 @@ EXPORT_SYMBOL(drm_dp_downstream_id);
> * @m: pointer for debugfs file
> * @dpcd: DisplayPort configuration data
> * @port_cap: port capabilities
> + * @edid: EDID
> * @aux: DisplayPort AUX channel
> *
> */
> void drm_dp_downstream_debug(struct seq_file *m,
> const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> - const u8 port_cap[4], struct drm_dp_aux *aux)
> + const u8 port_cap[4],
> + const struct edid *edid,
> + struct drm_dp_aux *aux)
> {
> bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> DP_DETAILED_CAP_INFO_AVAILABLE;
> @@ -789,7 +802,7 @@ void drm_dp_downstream_debug(struct seq_file *m,
> seq_printf(m, "\t\tMax TMDS clock: %d kHz\n",
> clk);
> }
>
> - bpc = drm_dp_downstream_max_bpc(dpcd, port_cap);
> + bpc = drm_dp_downstream_max_bpc(dpcd, port_cap, edid);
>
> if (bpc > 0)
> seq_printf(m, "\t\tMax bpc: %d\n", bpc);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index 53a0a3d9a22d..0bf31f9a8af5 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -626,6 +626,7 @@ static void intel_dp_info(struct seq_file *m,
> {
> struct intel_encoder *intel_encoder =
> intel_attached_encoder(intel_connector);
> struct intel_dp *intel_dp = enc_to_intel_dp(intel_encoder);
> + const struct drm_property_blob *edid = intel_connector-
> >base.edid_blob_ptr;
>
> seq_printf(m, "\tDPCD rev: %x\n", intel_dp->dpcd[DP_DPCD_REV]);
> seq_printf(m, "\taudio support: %s\n", yesno(intel_dp->has_audio));
> @@ -633,7 +634,7 @@ static void intel_dp_info(struct seq_file *m,
> intel_panel_info(m, &intel_connector->panel);
>
> drm_dp_downstream_debug(m, intel_dp->dpcd, intel_dp->downstream_ports,
> - &intel_dp->aux);
> + edid ? edid->data : NULL, &intel_dp->aux);
> }
>
> static void intel_dp_mst_info(struct seq_file *m,
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 2c8e82d97a34..c73b3efd84e0 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6071,7 +6071,7 @@ intel_dp_set_edid(struct intel_dp *intel_dp)
>
> intel_dp->dfp.max_bpc =
> drm_dp_downstream_max_bpc(intel_dp->dpcd,
> - intel_dp->downstream_ports);
> + intel_dp->downstream_ports, edid);
>
> drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] DFP max bpc %d\n",
> connector->base.base.id, connector->base.name,
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 4f946826dfce..6218de1294c1 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1646,10 +1646,14 @@ bool drm_dp_downstream_is_tmds(const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> const u8 port_cap[4]);
> int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> - const u8 port_cap[4]);
> + const u8 port_cap[4],
> + const struct edid *edid);
> int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
> -void drm_dp_downstream_debug(struct seq_file *m, const u8
> dpcd[DP_RECEIVER_CAP_SIZE],
> - const u8 port_cap[4], struct drm_dp_aux *aux);
> +void drm_dp_downstream_debug(struct seq_file *m,
> + const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> + const u8 port_cap[4],
> + const struct edid *edid,
> + struct drm_dp_aux *aux);
> enum drm_mode_subconnector
> drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> const u8 port_cap[4]);
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
