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drm/dp: Add drm_dp_dpcd_read_link_status()

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The function reads the link status (6 bytes starting at offset 0x202)
from the DPCD so that it can be conveniently passed to other DPCD
helpers.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Thierry Reding 2013-11-22 16:37:57 +01:00
parent c197db75ff
commit 8d4adc6a58
2 changed files with 19 additions and 0 deletions
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16
drivers/gpu/drm/drm_dp_helper.c
View file

@ -456,3 +456,19 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
size);
}
EXPORT_SYMBOL(drm_dp_dpcd_write);
/**
* drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
* @aux: DisplayPort AUX channel
* @status: buffer to store the link status in (must be at least 6 bytes)
*
* Returns the number of bytes transferred on success or a negative error
* code on failure.
*/
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
u8 status[DP_LINK_STATUS_SIZE])
{
return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
DP_LINK_STATUS_SIZE);
}
EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);

3
include/drm/drm_dp_helper.h
View file

@ -477,4 +477,7 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
return drm_dp_dpcd_write(aux, offset, &value, 1);
}
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
u8 status[DP_LINK_STATUS_SIZE]);
#endif /* _DRM_DP_HELPER_H_ */