diff options
| author | Jani Nikula | 2017-05-18 14:10:22 +0300 |
|---|---|---|
| committer | Jani Nikula | 2017-05-29 13:36:57 +0300 |
| commit | 118b90f3f18e733c99f0e8b98ea31a815ffc4d14 (patch) | |
| tree | c8a4302f16986bec4878eb1c014265821d5e1997 /drivers | |
| parent | 5ed02dbb497422bf225783f46e6eadd237d23d6b (diff) | |
drm/dp: add helper for reading DP sink/branch device desc from DPCD
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/acba54da7d80eafea9e59a893e27e3c31028c0ba.1495105635.git.jani.nikula@intel.com
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 3e5f52110ea1..52e0ca9a5bb1 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -1208,3 +1208,38 @@ int drm_dp_stop_crc(struct drm_dp_aux *aux) return 0; } EXPORT_SYMBOL(drm_dp_stop_crc); + +/** + * drm_dp_read_desc - read sink/branch descriptor from DPCD + * @aux: DisplayPort AUX channel + * @desc: Device decriptor to fill from DPCD + * @is_branch: true for branch devices, false for sink devices + * + * Read DPCD 0x400 (sink) or 0x500 (branch) into @desc. Also debug log the + * identification. + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc, + bool is_branch) +{ + struct drm_dp_dpcd_ident *ident = &desc->ident; + unsigned int offset = is_branch ? DP_BRANCH_OUI : DP_SINK_OUI; + int ret, dev_id_len; + + ret = drm_dp_dpcd_read(aux, offset, ident, sizeof(*ident)); + if (ret < 0) + return ret; + + dev_id_len = strnlen(ident->device_id, sizeof(ident->device_id)); + + DRM_DEBUG_KMS("DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d\n", + is_branch ? "branch" : "sink", + (int)sizeof(ident->oui), ident->oui, + dev_id_len, ident->device_id, + ident->hw_rev >> 4, ident->hw_rev & 0xf, + ident->sw_major_rev, ident->sw_minor_rev); + + return 0; +} +EXPORT_SYMBOL(drm_dp_read_desc); |