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 | 12 +++++++++++- include/drm/drm_dp_helper.h | 8 ++++++++ 2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 2c774ffa2943..0cf5b1c278ae 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -305,6 +305,7 @@ static void drm_dp_link_caps_reset(struct drm_dp_link_caps *caps) caps->enhanced_framing = false; caps->tps3_supported = false; caps->fast_training = false; + caps->channel_coding = false; }
void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest, @@ -313,6 +314,7 @@ void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest, dest->enhanced_framing = src->enhanced_framing; dest->tps3_supported = src->tps3_supported; dest->fast_training = src->fast_training; + dest->channel_coding = src->channel_coding; }
static void drm_dp_link_reset(struct drm_dp_link *link) @@ -359,6 +361,7 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) link->caps.enhanced_framing = drm_dp_enhanced_frame_cap(values); link->caps.tps3_supported = drm_dp_tps3_supported(values); link->caps.fast_training = drm_dp_fast_training_cap(values); + link->caps.channel_coding = drm_dp_channel_coding_supported(values);
link->rate = link->max_rate; link->lanes = link->max_lanes; @@ -445,7 +448,7 @@ 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); @@ -458,6 +461,13 @@ int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) if (err < 0) return err;
+ if (link->caps.channel_coding) + value = DP_SET_ANSI_8B10B; + + 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 bf280a4230fa..201e654b2257 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_CAP_ANSI_8B10B (1 << 0)
#define DP_DOWN_STREAM_PORT_COUNT 0x007 # define DP_PORT_COUNT_MASK 0x0f @@ -652,6 +653,12 @@ drm_dp_fast_training_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) (dpcd[DP_MAX_DOWNSPREAD] & DP_NO_AUX_HANDSHAKE_LINK_TRAINING); }
+static inline bool +drm_dp_channel_coding_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) +{ + return dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_8B10B; +} + /* * DisplayPort AUX channel */ @@ -766,6 +773,7 @@ struct drm_dp_link_caps { bool enhanced_framing; bool tps3_supported; bool fast_training; + bool channel_coding; };
void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest,