On a native AUX_CH transaction timeout, as per Spec 2.1 Section 2.3.4 says that if the AUX Reply Timeout timer timesout, DPTX can rety for 3 times because the No Reply may be due to the DPRX waking up from power-saving state. Export a function to wake the DP sink AUX_CH.
Signed-off-by: Arun R Murthy <[email protected]> --- drivers/gpu/drm/display/drm_dp_helper.c | 36 +++++++++++++++++++++++++++++++++ include/drm/display/drm_dp_helper.h | 1 + 2 files changed, 37 insertions(+) diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index a697cc227e28964cd8322803298178e7d788e820..1b8aa543ec3dc5819948af6f2724f3514b96b918 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -701,6 +701,42 @@ void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered) } EXPORT_SYMBOL(drm_dp_dpcd_set_powered); +/** + * drm_dp_wake_sink() - Try to wake up the sink device AUX_CH if in sleep + * + * @aux: DisplayPort AUX channel + */ +void drm_dp_wake_sink(struct drm_dp_aux *aux) +{ + const u8 wake_retry = 6; + u8 value = 0; + int ret = 0; + + /* + * Wake the sink device + * Spec DP2.1 section 2.3.1.2 if AUX CH is powered down by writing 0x02 + * to DP_SET_POWER dpcd reg, 1ms time would be required to wake it up + */ + ret = poll_timeout_us(ret = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value), + ret > 0, + 1000, wake_retry * 1000, true); + + /* + * If sink is in D3 then it may not respond to the AUX tx so + * wake it up to D3_AUX_ON state + * If the above poll_timeout_us fails, try waking the sink. + */ + if (value == DP_SET_POWER_D3 || ret < 0) { + /* After setting to D0 need a min of 1ms to wake(Spec DP2.1 sec 2.3.1.2) */ + drm_dp_dpcd_writeb(aux, DP_SET_POWER, + DP_SET_POWER_D0); + fsleep(1000); + drm_dp_dpcd_writeb(aux, DP_SET_POWER, + DP_SET_POWER_D3_AUX_ON); + } +} +EXPORT_SYMBOL(drm_dp_wake_sink); + /** * drm_dp_dpcd_set_probe() - Set whether a probing before DPCD access is done * @aux: DisplayPort AUX channel diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h index 1d0acd58f48676f60ff6a07cc6812f72cbb452e8..933428025c4d75ab7a0aa63039ed5f8e45ca625b 100644 --- a/include/drm/display/drm_dp_helper.h +++ b/include/drm/display/drm_dp_helper.h @@ -546,6 +546,7 @@ struct drm_dp_aux { bool dpcd_probe_disabled; }; +void drm_dp_wake_sink(struct drm_dp_aux *aux); int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset); void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered); void drm_dp_dpcd_set_probe(struct drm_dp_aux *aux, bool enable); -- 2.25.1
