SW revision is mandatory field for DisplayPort branch devices. This is defined in DPCD register field 0x50A.
Signed-off-by: Mika Kahola mika.kahola@intel.com --- drivers/gpu/drm/drm_dp_helper.c | 21 +++++++++++++++++++++ include/drm/drm_dp_helper.h | 2 ++ 2 files changed, 23 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index cfd75df..19e06a0 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -535,6 +535,27 @@ struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux) EXPORT_SYMBOL(drm_dp_downstream_hw_rev);
/** + * drm_dp_downstream_sw_rev() - read DP branch device SW revision + * @aux: DisplayPort AUX channel + * + * Returns SW revision on success or negative error code on failure + */ +struct drm_dp_revision drm_dp_downstream_sw_rev(struct drm_dp_aux *aux) +{ + uint8_t tmp[2]; + struct drm_dp_revision rev = { .major = -EINVAL, .minor = -EINVAL }; + + if (drm_dp_dpcd_read(aux, DP_BRANCH_SW_REV, tmp, 2) != 2) + return rev; + + rev.major = tmp[0]; + rev.minor = tmp[1]; + + return rev; +} +EXPORT_SYMBOL(drm_dp_downstream_sw_rev); + +/** * drm_dp_downstream_id() - identify branch device * @aux: DisplayPort AUX channel * diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 5f577e4..764a309 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -447,6 +447,7 @@ #define DP_BRANCH_OUI 0x500 #define DP_BRANCH_ID 0x503 #define DP_BRANCH_HW_REV 0x509 +#define DP_BRANCH_SW_REV 0x50A
#define DP_SET_POWER 0x600 # define DP_SET_POWER_D0 0x1 @@ -819,6 +820,7 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE], const u8 port_cap[4]); int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]); struct drm_dp_revision drm_dp_downstream_hw_rev(struct drm_dp_aux *aux); +struct drm_dp_revision drm_dp_downstream_sw_rev(struct drm_dp_aux *aux);
void drm_dp_aux_init(struct drm_dp_aux *aux); int drm_dp_aux_register(struct drm_dp_aux *aux);