diff options
Diffstat (limited to 'drivers/gpu/drm/tegra/dp.c')
| -rw-r--r-- | drivers/gpu/drm/tegra/dp.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/gpu/drm/tegra/dp.c b/drivers/gpu/drm/tegra/dp.c index 2be0a47ecbec..757a0256592f 100644 --- a/drivers/gpu/drm/tegra/dp.c +++ b/drivers/gpu/drm/tegra/dp.c @@ -40,6 +40,8 @@ static void drm_dp_link_reset(struct drm_dp_link *link) link->max_lanes = 0; drm_dp_link_caps_reset(&link->caps); + link->aux_rd_interval.cr = 0; + link->aux_rd_interval.ce = 0; link->edp = 0; link->rate = 0; @@ -60,6 +62,7 @@ static void drm_dp_link_reset(struct drm_dp_link *link) int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) { u8 dpcd[DP_RECEIVER_CAP_SIZE], value; + unsigned int rd_interval; int err; drm_dp_link_reset(link); @@ -90,6 +93,34 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) link->edp = drm_dp_edp_revisions[value]; } + /* + * The DPCD stores the AUX read interval in units of 4 ms. There are + * two special cases: + * + * 1) if the TRAINING_AUX_RD_INTERVAL field is 0, the clock recovery + * and channel equalization should use 100 us or 400 us AUX read + * intervals, respectively + * + * 2) for DP v1.4 and above, clock recovery should always use 100 us + * AUX read intervals + */ + rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] & + DP_TRAINING_AUX_RD_MASK; + + if (rd_interval > 4) { + DRM_DEBUG_KMS("AUX interval %u out of range (max. 4)\n", + rd_interval); + rd_interval = 4; + } + + rd_interval *= 4 * USEC_PER_MSEC; + + if (rd_interval == 0 || link->revision >= DP_DPCD_REV_14) + link->aux_rd_interval.cr = 100; + + if (rd_interval == 0) + link->aux_rd_interval.ce = 400; + link->rate = link->max_rate; link->lanes = link->max_lanes; |
