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author | Thierry Reding <treding@nvidia.com> | 2013-12-12 12:57:53 +0400 |
---|---|---|
committer | Thierry Reding <treding@nvidia.com> | 2014-02-26 20:21:34 +0400 |
commit | 88759686c702f1fbbb8e737e6231b64a9880db73 (patch) | |
tree | b803c33c31865165a95de0a7bfe68fb42082c1e3 /include/drm/drm_dp_helper.h | |
parent | 516c0f7c0a608833cc01d3f5b2a357ee806b78a1 (diff) | |
download | linux-88759686c702f1fbbb8e737e6231b64a9880db73.tar.xz |
drm/dp: Allow registering AUX channels as I2C busses
Implements an I2C-over-AUX I2C adapter on top of the generic drm_dp_aux
infrastructure. It extracts the retry logic from existing drivers, which
should help in porting those drivers to this new helper.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v5:
- move comments partially to to header file
- keep MOT set between I2C messages
- return -EPROTO on short reads
Changes in v4:
- fix typo "bitrate" -> "bit rate"
Changes in v3:
- add back DRM_DEBUG_KMS and DRM_ERROR messages
- embed i2c_adapter within struct drm_dp_aux
- fix typo in comment
Diffstat (limited to 'include/drm/drm_dp_helper.h')
-rw-r--r-- | include/drm/drm_dp_helper.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 28ab6f4e3b09..b7488c9849ad 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -421,6 +421,7 @@ struct drm_dp_aux_msg { /** * struct drm_dp_aux - DisplayPort AUX channel + * @ddc: I2C adapter that can be used for I2C-over-AUX communication * @dev: pointer to struct device that is the parent for this AUX channel * @transfer: transfers a message representing a single AUX transaction * @@ -435,8 +436,16 @@ struct drm_dp_aux_msg { * propagate errors from the .transfer() function, with the exception of * the -EBUSY error, which causes a transaction to be retried. On a short, * helpers will return -EPROTO to make it simpler to check for failure. + * + * An AUX channel can also be used to transport I2C messages to a sink. A + * typical application of that is to access an EDID that's present in the + * sink device. The .transfer() function can also be used to execute such + * transactions. The drm_dp_aux_register_i2c_bus() function registers an + * I2C adapter that can be passed to drm_probe_ddc(). Upon removal, drivers + * should call drm_dp_aux_unregister_i2c_bus() to remove the I2C adapter. */ struct drm_dp_aux { + struct i2c_adapter ddc; struct device *dev; ssize_t (*transfer)(struct drm_dp_aux *aux, @@ -497,4 +506,7 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link); int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link); int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_aux_register_i2c_bus(struct drm_dp_aux *aux); +void drm_dp_aux_unregister_i2c_bus(struct drm_dp_aux *aux); + #endif /* _DRM_DP_HELPER_H_ */ |