On 8/20/19 3:12 PM, David Francis wrote:
> The first step in MST DSC is checking MST endpoints
> to see how DSC can be enabled
>
> Case 1: DP-to-DP peer device
> if the branch immediately upstream has
> - PDT = DP_PEER_DEVICE_DP_MST_BRANCHING (2)
> - DPCD rev. >= DP 1.4
> - Exactly one input and one output
> - The output has PDT = DP_PEER_DEVICE_SST_SINK (3)
>
> In this case, DSC could be possible either on the endpoint
> or the peer device. Prefer the endpoint, which is possible if
> - The endpoint has DP_DSC_DECOMPRESSION_IS_SUPPORTED bit set
> - The endpoint has DP_FEC_CAPABLE bit set
> - The peer device has DSC_PASSTHROUGH_CAPABILITY bit set (from DP v2.0)
>
> Otherwise, use the peer device
>
> Case 2: DP-to-HDMI peer device
> If the output port has
> - PDT = DP_PEER_DEVICE_DP_LEGACY_CONV (4)
> - DPCD rev. >= DP 1.4
> - LDPS = true
> - MCS = false
>
> In this case, DSC can only be attempted on the peer device
> (the output port)
>
> Case 3: Virtual DP Sink (Internal Display Panel)
> If the output port has
> - DPCD rev. >= DP 1.4
> - port_num >= 8
>
> In this case, DSC can only be attempted on the peer device
> (the output port)
>
> Case 4: Synaptix Workaround
> If the output has
> - link DPCD rev. >= DP 1.4
> - link branch_dev_id = 0x90CC24 (Synaptix)
> - There is exactly one branch device between the link and output
>
> In this case, DSC can be attempted, but only using the *link*
> aux device's caps. This is a quirk.
>
> Test for these cases as modes are enumerated for an MST endpoint.
> We cannot do this during link attach because the dc_sink object
> will not have been created yet
>
> If no DSC is attempted, zero the DSC caps
>
> Cc: Wenjing Liu <Wenjing.Liu@xxxxxxx>
> Cc: Nikola Cornij <Nikola.Cornij@xxxxxxx>
> Signed-off-by: David Francis <David.Francis@xxxxxxx>
Questions and comments below...
> ---
> .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 123 +++++++++++++++++-
> .../display/amdgpu_dm/amdgpu_dm_mst_types.h | 3 +
> 2 files changed, 125 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> index 16218a202b59..58571844f6d5 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> @@ -25,6 +25,7 @@
>
> #include <linux/version.h>
> #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_dp_mst_helper.h>
> #include "dm_services.h"
> #include "amdgpu.h"
> #include "amdgpu_dm.h"
> @@ -189,6 +190,120 @@ static const struct drm_connector_funcs dm_dp_mst_connector_funcs = {
> .early_unregister = amdgpu_dm_mst_connector_early_unregister,
> };
>
> +bool is_virtual_dpcd(struct drm_dp_mst_port *port)
> +{
> + struct drm_dp_mst_port *downstream_port;
> +
> + if (!port)
> + return false;
> +
> + if (port->port_num >= 8 &&
> + port->dpcd_rev >= DP_DPCD_REV_14) {
All these if statements should be aligned if possible. That's just
formatting nitpicks though.
> + /* Virtual DP Sink (Internal Display Panel) */
> + return true;
> + } else if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
> + !port->mcs &&
> + port->ldps &&
> + port->dpcd_rev >= DP_DPCD_REV_14) {
> + /* DP-to-HDMI Protocol Converter */
> + return true;
> + } else if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
> + port->mstb &&
> + port->dpcd_rev >= DP_DPCD_REV_14) {
> + /* DP-to-DP */
> + if (port->mstb->num_ports == 2) {
Can probably merge this if condition into the else if above. Will help
cut down on line length below.
> + list_for_each_entry(downstream_port, &port->mstb->ports, next) {
> + if (!downstream_port->input &&
> + downstream_port->pdt == DP_PEER_DEVICE_SST_SINK)
> + return true;
> + }
> + }
> + }
> + return false;
> +} > +
> +bool synaptix_workaround(struct amdgpu_dm_connector *aconnector)
This probably needs a better name. This isn't applying a workaround for
a specific device but returning true if it is a specific device.
> +{
> + struct drm_dp_mst_port *port = aconnector->port;
> + struct dc_link *link = aconnector->dc_sink->link;
> + u8 down_stream_port_data;
> +
> + if (port->mgr->mst_primary == port->parent &&
> + link->dpcd_caps.branch_dev_id == 0x90CC24 &&
> + link->dpcd_caps.dpcd_rev.raw >= DP_DPCD_REV_14) {
> + drm_dp_mst_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT, &down_stream_port_data, 1);
> + if ((down_stream_port_data & 7) != 3)
> + return true;
> + }
> + return false;
> +}
> +
> +#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
> +static bool validate_dsc_caps_on_connector(struct amdgpu_dm_connector *aconnector)
> +{
> + u8 upstream_dsc_caps[16] = { 0 };
> + u8 endpoint_dsc_caps[16] = { 0 };
> + u8 endpoint_fec_caps = 0;
> + struct dc_sink *dc_sink = aconnector->dc_sink;
> + struct drm_dp_mst_port *output_port = aconnector->port;
> + struct drm_dp_mst_port *immediate_upstream_port;
> + struct drm_dp_mst_port *fec_port;
> +
> + if (aconnector->port && aconnector->port->parent)
> + immediate_upstream_port = aconnector->port->parent->port_parent;
> + else
> + immediate_upstream_port = NULL;
> +
> + fec_port = immediate_upstream_port;
> + while (fec_port) {
> + if (!fec_port->fec_capable)
> + return false;
> +
> + fec_port = fec_port->parent->port_parent;
> + }
> +
> + if (immediate_upstream_port)
> + drm_dp_mst_dpcd_read(&immediate_upstream_port->aux, DP_DSC_SUPPORT, upstream_dsc_caps, 16);
> + drm_dp_mst_dpcd_read(&output_port->aux, DP_DSC_SUPPORT, endpoint_dsc_caps, 16);
> + drm_dp_mst_dpcd_read(&output_port->aux, DP_FEC_CAPABILITY, &endpoint_fec_caps, 1);
> +
> + if (is_virtual_dpcd(immediate_upstream_port)
> + && (upstream_dsc_caps[0] & 0x2) /* DSC passthrough capability */
> + && (endpoint_fec_caps & DP_FEC_CAPABLE)
> + && (endpoint_dsc_caps[0] & DP_DSC_DECOMPRESSION_IS_SUPPORTED)) {
> + /* Enpoint decompression with DP-to-DP peer device */
> + if (!dc_dsc_parse_dsc_dpcd(endpoint_dsc_caps, NULL, &dc_sink->sink_dsc_caps.dsc_dec_caps))
> + return false;
> +
> + dc_sink->sink_dsc_caps.is_virtual_dpcd_dsc = false;
> + } else if (is_virtual_dpcd(immediate_upstream_port)) {
> + /* Virtual DPCD decompression with DP-to-DP peer device */
> + if (!dc_dsc_parse_dsc_dpcd(upstream_dsc_caps, NULL, &dc_sink->sink_dsc_caps.dsc_dec_caps))
> + return false;
> +
> + dc_sink->sink_dsc_caps.is_virtual_dpcd_dsc = true;
> + } else if (is_virtual_dpcd(output_port)) {
> + /* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
> + if (!dc_dsc_parse_dsc_dpcd(endpoint_dsc_caps, NULL, &dc_sink->sink_dsc_caps.dsc_dec_caps))
> + return false;
> +
> + dc_sink->sink_dsc_caps.is_virtual_dpcd_dsc = true;
> + } else if (synaptix_workaround(aconnector)) {
> + /* Synaptix workaround */
> + aconnector = dc_sink->link->priv;
> + drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, DP_DSC_SUPPORT, upstream_dsc_caps, 16);
> + if (!dc_dsc_parse_dsc_dpcd(upstream_dsc_caps, NULL, &dc_sink->sink_dsc_caps.dsc_dec_caps))
> + return false;
> +
> + dc_sink->sink_dsc_caps.is_virtual_dpcd_dsc = true;
> + } else {
> + return false;
> + }
> +
> + return true;
> +}
> +#endif
Should this be common code instead as a dp mst helper for determining
caps? Other than setting the dc sink stuff the rest looks like it could
be common but I'm not overly familiar with the architecture.
> +
> static int dm_dp_mst_get_modes(struct drm_connector *connector)
> {
> struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
> @@ -231,10 +346,16 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
> /* dc_link_add_remote_sink returns a new reference */
> aconnector->dc_sink = dc_sink;
>
> - if (aconnector->dc_sink)
> + if (aconnector->dc_sink) {
> amdgpu_dm_update_freesync_caps(
> connector, aconnector->edid);
>
> +#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
> + if (!validate_dsc_caps_on_connector(aconnector))
> + memset(&aconnector->dc_sink->sink_dsc_caps,
> + 0, sizeof(aconnector->dc_sink->sink_dsc_caps));
> +#endif
> + }
> }
>
> drm_connector_update_edid_property(
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h
> index 2da851b40042..8de3d8c30f8d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h
> @@ -32,4 +32,7 @@ struct amdgpu_dm_connector;
> void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
> struct amdgpu_dm_connector *aconnector);
>
> +bool is_virtual_dpcd(struct drm_dp_mst_port *port);
> +bool synaptix_workaround(struct amdgpu_dm_connector *aconnector);
These shouldn't be defined in the header if they're only going to be
used here, they should just be static.
> +
> #endif
>
Nicholas Kazlauskas
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