On 28.08.2018 12:24, Damian Kos wrote:

From: Quentin Schulz <redacted>

DP 1.4 introduced a DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit in
DP_TRAINING_AUX_RD_INTERVAL register. If set, DPCD registers from DP_DPCD_REV
to DP_ADAPTER_CAP should be retrieved starting from DP_DPCD_REV_EXTENDED.
All registers are copied except DP_DPCD_REV, DP_MAX_LINK_RATE and
DP_DOWNSTREAMPORT_PRESENT which represent the "true capabilities" of DPRX
device.

Original DP_DPCD_REV, DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT might
falsely return lower capabilities to "avoid interoperability issues with some
of the existing DP Source devices that malfunction when they discover the
higher capabilities within those three registers.".

Before DP 1.4, DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit was reserved and read 0
so it's safe to check against it even if DP revision is <1.4

Signed-off-by: Damian Kos <redacted>

Here and in next patches signed-off-by of the author is missing.

With that fixed:
Reviewed-by: Andrzej Hajda <redacted>

?--
Regards
Andrzej