On Mon, Jun 06, 2016 at 04:29:04PM +0300, Mika Kahola wrote:
> Read DisplayPort downstream port capabilities. Depending on
> the DP port the capabilities are defined in length of 1 byte
> or 4 bytes depending if the detailed capability information is
> available.
>
> Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++++++++++++
> include/drm/drm_dp_helper.h | 3 +++
> 2 files changed, 30 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index eeaf5a7..c4149fd 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -438,6 +438,33 @@ int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
> }
> EXPORT_SYMBOL(drm_dp_link_configure);
>
> +/**
> + * drm_dp_downstream_port_cap() - read downstream port capabilities
> + * @dpcd: DisplayPort configuration data
> + * @port_cap: port capabilities
> + *
> + * returns size of the port capabilites
> + */
> +int drm_dp_downstream_port_cap(struct drm_dp_aux *aux,
> + const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> + u8 port_cap[4])
> +{
> + int size;
> + bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
> + DP_DETAILED_CAP_INFO_AVAILABLE;
> +
> + if (detailed_cap_info) {
> + size = 4;
> + drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, port_cap, size);
> + } else {
> + size = 1;
> + drm_dp_dpcd_read(aux, DP_DOWNSTREAM_PORT_0, &port_cap[0], size);
> + }
Could avoid a bit of duplicatetion. Eg.:
if (dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE)
size = 4;
else
size = 1;
return drm_dp_dpcd_read(...);
Though perhaps we should just read out the entire 4/16 bytes to get the
caps for all the ports?
> +
> + return size;
> +}
> +EXPORT_SYMBOL(drm_dp_downstream_port_cap);
> +
> /*
> * I2C-over-AUX implementation
> */
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index e384c7f..db8d3d47 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -806,6 +806,9 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
> int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
> int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
> int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
> +int drm_dp_downstream_port_cap(struct drm_dp_aux *aux,
> + const u8 dpcd[DP_RECEIVER_CAP_SIZE],
> + u8 port_cap[4]);
>
> int drm_dp_aux_register(struct drm_dp_aux *aux);
> void drm_dp_aux_unregister(struct drm_dp_aux *aux);
> --
> 1.9.1
--
Ville Syrjälä
Intel OTC
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