Great work!
Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
On Wed, 2019-09-18 at 16:26 -0400, mikita.lipski@xxxxxxx wrote:
> From: David Francis <David.Francis@xxxxxxx>
>
> Synaptics DP1.4 hubs (BRANCH_ID 0x90CC24) do not
> support virtual DPCD registers, but do support DSC.
> The DSC caps can be read from the physical aux,
> like in SST DSC. These hubs have many different
> DEVICE_IDs. Add a new quirk to detect this case.
>
> Change-Id: I9d332f273dfca0cfbced111e62f5a06c5c312893
> Cc: Lyude Paul <lyude@xxxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Harry Wentland <harry.wentland@xxxxxxx>
> Reviewed-by: Wenjing Liu <Wenjing.Liu@xxxxxxx>
> Signed-off-by: David Francis <David.Francis@xxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 4 +++-
> drivers/gpu/drm/drm_dp_mst_topology.c | 27 +++++++++++++++++++++++++++
> include/drm/drm_dp_helper.h | 7 +++++++
> 3 files changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c
> b/drivers/gpu/drm/drm_dp_helper.c
> index 0cbf10727bd6..c3e1da78e442 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -1288,7 +1288,9 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
> /* LG LP140WF6-SPM1 eDP panel */
> { OUI(0x00, 0x22, 0xb9), DEVICE_ID('s', 'i', 'v', 'a', 'r', 'T'),
> false, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
> /* Apple panels need some additional handling to support PSR */
> - { OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false,
> BIT(DP_DPCD_QUIRK_NO_PSR) }
> + { OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false,
> BIT(DP_DPCD_QUIRK_NO_PSR) },
> + /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
> + { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true,
> BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
> };
>
> #undef OUI
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index dd2ca065cc92..4e493d8af288 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -4219,6 +4219,7 @@ struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct
> drm_dp_mst_port *port)
> {
> struct drm_dp_mst_port *immediate_upstream_port;
> struct drm_dp_mst_port *fec_port;
> + struct drm_dp_desc desc = { 0 };
>
> if (!port)
> return NULL;
> @@ -4271,6 +4272,32 @@ struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct
> drm_dp_mst_port *port)
> if (drm_dp_mst_is_virtual_dpcd(port))
> return &port->aux;
>
> + /*
> + * Synaptics quirk
> + * Applies to ports for which:
> + * - Physical aux has Synaptics OUI
> + * - DPv1.4 or higher
> + * - Port is on primary branch device
> + * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
> + */
> + if (!drm_dp_read_desc(port->mgr->aux, &desc, true))
> + return NULL;
> +
> + if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
> + port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
> + port->parent == port->mgr->mst_primary) {
> + u8 downstreamport;
> +
> + if (drm_dp_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT,
> + &downstreamport, 1) < 0)
> + return NULL;
> +
> + if ((downstreamport & DP_DWN_STRM_PORT_PRESENT) &&
> + ((downstreamport & DP_DWN_STRM_PORT_TYPE_MASK)
> + != DP_DWN_STRM_PORT_TYPE_ANALOG))
> + return port->mgr->aux;
> + }
> +
> return NULL;
> }
> EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 6ae1a6765f63..919ad940bfb1 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1414,6 +1414,13 @@ enum drm_dp_quirk {
> * driver still need to implement proper handling for such device.
> */
> DP_DPCD_QUIRK_NO_PSR,
> + /**
> + * @DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD:
> + *
> + * The device supports MST DSC despite not supporting Virtual DPCD.
> + * The DSC caps can be read from the physical aux instead.
> + */
> + DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD,
> };
>
> /**
--
Cheers,
Lyude Paul
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