From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6FE13CD4F5B for ; Wed, 20 May 2026 02:40:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1724210E401; Wed, 20 May 2026 02:40:11 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="H28UTJNU"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id EB40110E401; Wed, 20 May 2026 02:40:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1779244810; x=1810780810; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=X2UCFEN1/Udn1m9a84U9bhkGIgg0UwlQXA7op23h144=; b=H28UTJNU2AOeEa/WAmo4qmPmFXbyJXTLZe2uEBJFRxFb6oydpVAxssko I2nCtORiLfBXwiDTgOKg+0af51/bdISSB+ayTNJPc4x3/TEvjsjJckzgv 1X9H/qDF5lDiy9RK1zieRX1NHsaimLTZqHkhgiN4Sky4BrPZOwjaDJWc4 oV0bbNSR/+VzJFOiLzHKtWyUh28ndMQ1ZlB80mMGwnnMNBv4+SjwiowS0 +6Ccpxz5PstNIFsXZ3uRav7cx/PGiOWnKcNmqa7cj581A26ltoIW8LaLz 0PqGPdCYHwneRNbdlvTxNOk2vuNzeHbeiUzoVyEfjHWsha5NXdNwFEUmb A==; X-CSE-ConnectionGUID: Y46t5bEtRTihZKmalAVnrg== X-CSE-MsgGUID: eCZBjoR5QeOdmI4DSoGsBg== X-IronPort-AV: E=McAfee;i="6800,10657,11791"; a="79158634" X-IronPort-AV: E=Sophos;i="6.23,243,1770624000"; d="scan'208";a="79158634" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2026 19:40:09 -0700 X-CSE-ConnectionGUID: nXs7Oc9nTvqsLfurIsi8vw== X-CSE-MsgGUID: WERRNSXRTYuuy7j5WiZ1lw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,243,1770624000"; d="scan'208";a="263764477" Received: from srr4-3-linux-103-aknautiy.iind.intel.com ([10.223.34.160]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2026 19:40:07 -0700 From: Ankit Nautiyal To: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Cc: Jerome Tollet , Jerome Tollet , Ankit Nautiyal , Arun R Murthy Subject: [RESEND] drm/i915/hdmi: Poll for 200 msec for TMDS_Scrambler_Status Date: Wed, 20 May 2026 07:55:44 +0530 Message-ID: <20260520022544.3097252-1-ankit.k.nautiyal@intel.com> X-Mailer: git-send-email 2.45.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" From: Jerome Tollet HDMI 2.0 section 6.1.3.1 specifies that after enabling Scrambling_Enable and starting scrambled video transmission, the source should poll Scrambling_Status until it reads 1 or until a timeout of 200 ms expires. Add a polling step after enabling the HDMI port to check the scrambling status when HDMI scrambling is enabled. On some HDMI 2.0 sinks, omitting this check can result in 4K@60Hz (594 MHz) failing to come up correctly because the sink has not yet finished its scrambling setup. In practice, waiting for the scrambling status here fixes such sinks. While this synchronous polling is not itself explicitly required for correct modeset sequencing, HDMI 2.0 section 6.1.3.1 does recommend it as the way for the source to verify that the TMDS link is functioning correctly with scrambling enabled. v3: - Add explicit HDMI 2.0 section reference in code comment - Clarify commit message around the observed sink fix v2: - Poll TMDS_Scrambler_Status for up to 200 ms instead of using a fixed delay Reported-by: Jerome Tollet Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6868 Link: https://lore.kernel.org/dri-devel/20251230091037.5603-1-jerome.tollet@gmail.com/ Signed-off-by: Jerome Tollet Signed-off-by: Ankit Nautiyal Reviewed-by: Arun R Murthy --- Resend to intel-gfx and intel-xe so that the patch is picked up by intel gfx CI. --- drivers/gpu/drm/i915/display/intel_ddi.c | 2 ++ drivers/gpu/drm/i915/display/intel_hdmi.c | 26 +++++++++++++++++++++++ drivers/gpu/drm/i915/display/intel_hdmi.h | 2 ++ 3 files changed, 30 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c index 86520848892e..ac307a53576b 100644 --- a/drivers/gpu/drm/i915/display/intel_ddi.c +++ b/drivers/gpu/drm/i915/display/intel_ddi.c @@ -3505,6 +3505,8 @@ static void intel_ddi_enable_hdmi(struct intel_atomic_state *state, } intel_ddi_buf_enable(encoder, buf_ctl); + + intel_hdmi_poll_for_scrambling_enable(crtc_state, connector); } static void intel_ddi_enable(struct intel_atomic_state *state, diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c index 9076c2b176ec..b9d11fb8559d 100644 --- a/drivers/gpu/drm/i915/display/intel_hdmi.c +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c @@ -2728,6 +2728,32 @@ intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *_ drm_connector_attach_max_bpc_property(&connector->base, 8, 12); } +/* + * HDMI 2.0 spec, section 6.1.3.1 (Scrambling Control): after + * enabling Scrambling_Enable and starting scrambled video + * transmission, poll Scrambling_Status for up to 200 ms. + */ +void +intel_hdmi_poll_for_scrambling_enable(const struct intel_crtc_state *crtc_state, + struct drm_connector *_connector) +{ + struct intel_connector *connector = to_intel_connector(_connector); + struct intel_display *display = to_intel_display(crtc_state); + bool scrambling_enabled = false; + int ret; + + if (!crtc_state->hdmi_scrambling) + return; + + /* Poll for a max of 200 msec as per HDMI spec */ + ret = poll_timeout_us(scrambling_enabled = drm_scdc_get_scrambling_status(&connector->base), + scrambling_enabled, 1000, 200 * 1000, false); + if (ret) + drm_dbg_kms(display->drm, + "[CONNECTOR:%d:%s] Timed out waiting for scrambling enable\n", + connector->base.base.id, connector->base.name); +} + /* * intel_hdmi_handle_sink_scrambling: handle sink scrambling/clock ratio setup * @encoder: intel_encoder diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.h b/drivers/gpu/drm/i915/display/intel_hdmi.h index be2fad57e4ad..0fa3661568e8 100644 --- a/drivers/gpu/drm/i915/display/intel_hdmi.h +++ b/drivers/gpu/drm/i915/display/intel_hdmi.h @@ -70,5 +70,7 @@ void hsw_read_infoframe(struct intel_encoder *encoder, const struct intel_crtc_state *crtc_state, unsigned int type, void *frame, ssize_t len); +void intel_hdmi_poll_for_scrambling_enable(const struct intel_crtc_state *crtc_state, + struct drm_connector *_connector); #endif /* __INTEL_HDMI_H__ */ -- 2.45.2