[PATCH v3 2/5] drm/dp: fix link probing for devices supporting DP 1.4+

Andrzej Hajda a.hajda at samsung.com
Thu Sep 13 04:08:27 PDT 2018


On 28.08.2018 12:24, Damian Kos wrote:
> From: Quentin Schulz <quentin.schulz at bootlin.com>
>
> 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 <dkos at cadence.com>

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

With that fixed:
Reviewed-by: Andrzej Hajda <a.hajda at samsung.com>

 --
Regards
Andrzej





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