drm/i915: Fix fast wake AUX sync len

commit e1c71f8f91 upstream.

Fast wake should use 8 SYNC pulses for the preamble
and 10-16 SYNC pulses for the precharge. Reduce our
fast wake SYNC count to match the maximum value.
We also use the maximum precharge length for normal
AUX transactions.

Cc: stable@vger.kernel.org
Cc: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329172434.18744-1-ville.syrjala@linux.intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
(cherry picked from commit 605f7c7313)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/i915/display/intel_dp_aux.c

@@ -167,7 +167,7 @@ static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp,
 	      DP_AUX_CH_CTL_TIME_OUT_MAX |
 	      DP_AUX_CH_CTL_RECEIVE_ERROR |
 	      (send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
-	      DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(32) |
+	      DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(24) |
 	      DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
 
 	if (intel_phy_is_tc(i915, phy) &&