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drm: Helper to read max bits per component

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Helper routine to read out maximum supported bits per
component for DisplayPort legay converters.

v2: Return early if detailed port cap info is not available.
    Replace if-else ladder with switch-case (Ville)

Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473419458-17080-5-git-send-email-mika.kahola@intel.com
This commit is contained in:
Mika Kahola 2016-09-09 14:10:50 +03:00 committed by Jani Nikula
parent 1c29bd3d60
commit 7529d6af1c
2 changed files with 44 additions and 0 deletions
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42
drivers/gpu/drm/drm_dp_helper.c
View file

@ -471,6 +471,48 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
}
EXPORT_SYMBOL(drm_dp_downstream_max_clock);
/**
* drm_dp_downstream_max_bpc() - extract branch device max
* bits per component
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Returns max bpc on success or 0 if max bpc not defined
*/
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
int bpc;
if (!detailed_cap_info)
return 0;
switch (type) {
case DP_DS_PORT_TYPE_VGA:
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
case DP_DS_PORT_TYPE_DP_DUALMODE:
bpc = port_cap[2] & DP_DS_MAX_BPC_MASK;
switch (bpc) {
case DP_DS_8BPC:
return 8;
case DP_DS_10BPC:
return 10;
case DP_DS_12BPC:
return 12;
case DP_DS_16BPC:
return 16;
}
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
/*
* I2C-over-AUX implementation
*/

2
include/drm/drm_dp_helper.h
View file

@ -817,6 +817,8 @@ 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_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4]);
void drm_dp_aux_init(struct drm_dp_aux *aux);
int drm_dp_aux_register(struct drm_dp_aux *aux);