From: Thierry Reding treding@nvidia.com
Make use of ANSI 8B/10B channel coding if the DisplayPort sink supports it.
Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/drm_dp_helper.c | 16 ++++++++++++++-- include/drm/drm_dp_helper.h | 2 ++ 2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index bf480a08d7f9..c48addaf4301 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -295,7 +295,7 @@ EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); */ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) { - u8 values[4]; + u8 values[7]; int err;
memset(link, 0, sizeof(*link)); @@ -314,6 +314,9 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) if (values[3] & DP_NO_AUX_HANDSHAKE_LINK_TRAINING) link->capabilities |= DP_LINK_CAP_FAST_TRAINING;
+ if (values[6] & DP_SET_ANSI_8B10B) + link->capabilities |= DP_LINK_CAP_ANSI_8B10B; + return 0; } EXPORT_SYMBOL(drm_dp_link_probe); @@ -396,7 +399,7 @@ EXPORT_SYMBOL(drm_dp_link_power_down); */ int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) { - u8 values[2]; + u8 values[2], value = 0; int err;
values[0] = drm_dp_link_rate_to_bw_code(link->rate); @@ -409,6 +412,15 @@ int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) if (err < 0) return err;
+ if (link->capabilities & DP_LINK_CAP_ANSI_8B10B) + value = DP_SET_ANSI_8B10B; + else + value = 0; + + err = drm_dp_dpcd_writeb(aux, DP_MAIN_LINK_CHANNEL_CODING_SET, value); + if (err < 0) + return err; + return 0; } EXPORT_SYMBOL(drm_dp_link_configure); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 61c0518704a3..83be142395ff 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -88,6 +88,7 @@ # define DP_DETAILED_CAP_INFO_AVAILABLE (1 << 4) /* DPI */
#define DP_MAIN_LINK_CHANNEL_CODING 0x006 +# define DP_CODING_ANSI_8B10B (1 << 0)
#define DP_DOWN_STREAM_PORT_COUNT 0x007 # define DP_PORT_COUNT_MASK 0x0f @@ -743,6 +744,7 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, */ #define DP_LINK_CAP_ENHANCED_FRAMING (1 << 0) #define DP_LINK_CAP_FAST_TRAINING (1 << 1) +#define DP_LINK_CAP_ANSI_8B10B (1 << 2)
struct drm_dp_link { unsigned char revision;