diff options
Diffstat (limited to 'drivers/gpu/drm/display/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/display/drm_dp_helper.c | 44 |
1 files changed, 30 insertions, 14 deletions
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index 896bba2adb3ba..385a1bfdb2729 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -693,6 +693,34 @@ void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered) EXPORT_SYMBOL(drm_dp_dpcd_set_powered); /** + * drm_dp_dpcd_set_probe() - Set whether a probing before DPCD access is done + * @aux: DisplayPort AUX channel + * @enable: Enable the probing if required + */ +void drm_dp_dpcd_set_probe(struct drm_dp_aux *aux, bool enable) +{ + WRITE_ONCE(aux->dpcd_probe_disabled, !enable); +} +EXPORT_SYMBOL(drm_dp_dpcd_set_probe); + +static bool dpcd_access_needs_probe(struct drm_dp_aux *aux) +{ + /* + * HP ZR24w corrupts the first DPCD access after entering power save + * mode. Eg. on a read, the entire buffer will be filled with the same + * byte. Do a throw away read to avoid corrupting anything we care + * about. Afterwards things will work correctly until the monitor + * gets woken up and subsequently re-enters power save mode. + * + * The user pressing any button on the monitor is enough to wake it + * up, so there is no particularly good place to do the workaround. + * We just have to do it before any DPCD access and hope that the + * monitor doesn't power down exactly after the throw away read. + */ + return !aux->is_remote && !READ_ONCE(aux->dpcd_probe_disabled); +} + +/** * drm_dp_dpcd_read() - read a series of bytes from the DPCD * @aux: DisplayPort AUX channel (SST or MST) * @offset: address of the (first) register to read @@ -713,20 +741,8 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, { int ret; - /* - * HP ZR24w corrupts the first DPCD access after entering power save - * mode. Eg. on a read, the entire buffer will be filled with the same - * byte. Do a throw away read to avoid corrupting anything we care - * about. Afterwards things will work correctly until the monitor - * gets woken up and subsequently re-enters power save mode. - * - * The user pressing any button on the monitor is enough to wake it - * up, so there is no particularly good place to do the workaround. - * We just have to do it before any DPCD access and hope that the - * monitor doesn't power down exactly after the throw away read. - */ - if (!aux->is_remote) { - ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV); + if (dpcd_access_needs_probe(aux)) { + ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS); if (ret < 0) return ret; } |