Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] The newly added early return in `dpcd_write_rx_power_ctrl()` incorrectly relies on `link->aux_mode` before it is initialized, causing the DP receiver power-up sequence to be skipped for all newly detected DP monitors and active dongles. --
commit 6bcb07f6c6cfc4188f9856f76b47789a74cb855e Author: NepNep7601 <[email protected]> drm/amd/display: skip receiver power control without AUX Passive DP to TMDS dongles do not provide a DP receiver and use native GPIO I2C rather than AUX. dpcd_write_rx_power_ctrl() nevertheless tries to write DP_SET_POWER, causing the DP helpers to retry a transaction that cannot succeed 32 times before giving up. Skip receiver power control when the link is not using AUX mode. > diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c > b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c > index 49521ac4b0e85..7991531f6ef44 100644 > --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c > +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_phy.c > @@ -50,6 +50,15 @@ void dpcd_write_rx_power_ctrl(struct dc_link *link, bool > on) > if (link->sync_lt_in_progress) > return; > > + /* > + * A passive DP to TMDS dongle presents no DP receiver, so there is > + * nothing to power up or down. The write can only fail, and the DP > + * helpers retry it 32 times before giving up, which adds tens of > + * milliseconds to link bring up. > + */ > + if (!link->aux_mode) > + return; [Severity: High] Does this early return skip the DP receiver power-up sequence for all newly detected DP monitors and active dongles? During system boot or display hotplug, the dc_link struct is zero-allocated, so link->aux_mode defaults to false. The detection sequence starts with detect_link_and_local_sink(), which calls detect_dp() -> retrieve_link_cap() -> dp_wa_power_up_0010FA(), eventually calling dpcd_write_rx_power_ctrl(). Since link->aux_mode is still false at this point, the early return triggers and skips the DP_SET_POWER D0 write. This breaks detection for active dongles (such as the 0010FA) that depend on being powered up before a DPCD read. Looking at detect_link_and_local_sink() in link_detection.c, link->aux_mode is actually initialized after detect_dp() has already executed and failed: drivers/gpu/drm/amd/display/dc/link/link_detection.c:detect_link_and_local_sink() { ... if (!detect_dp(link, &sink_caps, reason)) { ... link->aux_mode = link_is_in_aux_transaction_mode(link->ddc); ... } Should we ensure link->aux_mode is initialized earlier in the detection flow, or use a different condition to skip the power control write? > + > core_link_write_dpcd(link, DP_SET_POWER, &state, > sizeof(state)); > -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
