From: Gustavo Sousa Date: Tue, 16 Dec 2025 21:12:01 +0000 (-0300) Subject: drm/i915/cx0: Toggle powerdown states for C10 on HDMI X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9236cf0ade32f5b7fa5424c20663fa7ea40f8bcb;p=thirdparty%2Fkernel%2Flinux.git drm/i915/cx0: Toggle powerdown states for C10 on HDMI A new step has been added to Bspec with respect to the C10 PHY, which instructs the driver to toggle powerdown value for boths PHY lanes to P0 and then P2 when driving an HDMI connector. This update in the Bspec reflects the changes required by Wa_14026084006, so document it. Note that, unlike other display workarounds, this one is actually tied to the C10 PHY and not to a specific display IP. As such, let's just document it in intel_cx0_phy.c instead of adding it to intel_display_wa.c. Bspec: 64568, 74489 Reviewed-by: Dnyaneshwar Bhadane Link: https://patch.msgid.link/20251216-wa_14026084006-c10-hdmi-toggle-powerdown-v1-2-08677b03e2f1@intel.com Signed-off-by: Gustavo Sousa --- diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c index 264f8a5072e5..2c87c58812da 100644 --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c @@ -3302,6 +3302,21 @@ static void intel_cx0pll_enable(struct intel_encoder *encoder, * Frequency Change. We handle this step in bxt_set_cdclk(). */ + /* + * 12. Toggle powerdown if HDMI is enabled on C10 PHY. + * + * Wa_13013502646: + * Fixes: HDMI lane to lane skew violations on C10 display PHYs. + * Workaround: Toggle powerdown value by setting first to P0 and then to P2, for both + * PHY lanes. + */ + if (!cx0pll_state_is_dp(pll_state) && pll_state->use_c10) { + intel_cx0_powerdown_change_sequence(encoder, INTEL_CX0_BOTH_LANES, + XELPDP_P0_STATE_ACTIVE); + intel_cx0_powerdown_change_sequence(encoder, INTEL_CX0_BOTH_LANES, + XELPDP_P2_STATE_READY); + } + intel_cx0_phy_transaction_end(encoder, wakeref); }