From nobody Thu Apr 9 13:37:37 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0724E265298 for ; Mon, 9 Mar 2026 07:32:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773041557; cv=none; b=I/fAgRCNtFEIyy5GAxJ9bn1ok8IYvWXSfYqVe7Kfes51zAsgQm77crrozrAvpiaxI6pfm6M7FCr96/JHvX6E6ZL+hHbM+hBl2iFlQDfixfJi4XDHqORJpwZ/7z/vdTcXdmn2sOgFcqkTyY1k0C2SLPAidLtsv98DDVXvqNXtD2I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773041557; c=relaxed/simple; bh=0qNNpnP3lyZH3HdmWjAPRNRTyd2jswfseZV6vLDwdXM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=eG2AsMqFHm5FG6kc8PHHPlV0FsXiib8qobQhrY1bcYZcKEzbm6j34Dj0YPynZZyUkDE7QHF/UVDZl5E4MidHSwaZujD1IbUaamKLCWn7he44XvFla+QRUy0azFrjt+5s4oRBZLrBmVPbvJhJrX0mdjxmFqEG/S9hneysb4Gw92o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=a2qj8pCD; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="a2qj8pCD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1773041556; x=1804577556; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=0qNNpnP3lyZH3HdmWjAPRNRTyd2jswfseZV6vLDwdXM=; b=a2qj8pCDqIDmlO7i2L8y7VZ39nQn8/opSV2o2TQLzlf4bAA6rzHb9bOA nMhC5Paxn+ec/mUyMGz4aWej/VrsVw5gHPlGuzufK1ME75ohkXrznD1Fp AvrTWigLaxEI3sSLok6aLg5oJU5+Hz27CfcA5MBmcCdXKe0x9ynHAw/OG ue6DSkLE9Cv6HP9pH8f0mFrfChdvJrbNmFlhaS0b/vLAgoO+mA7EWco0y s8+CjiyVjwGJatBisRm9PuBKVy4yz6iS7tR3QyYwt4KwcUB7QggnhsEdT OpfU07wtSl4g9zJN0fERFcDTWsSidXyMD7cRSSXYxRfCjZOHZnzQAUf3Y A==; X-CSE-ConnectionGUID: XRS28remSXCDGkvXm5r1Lg== X-CSE-MsgGUID: hBCAL0kGTfaMa1qGlL8ooQ== X-IronPort-AV: E=McAfee;i="6800,10657,11723"; a="77935646" X-IronPort-AV: E=Sophos;i="6.23,109,1770624000"; d="scan'208";a="77935646" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2026 00:31:06 -0700 X-CSE-ConnectionGUID: /iEYHDqqQSyCz+NV4+ewNg== X-CSE-MsgGUID: zdJlzA9pTQSXq1tTIPc88Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,109,1770624000"; d="scan'208";a="217286718" Received: from srr4-3-linux-106-armuthy.iind.intel.com ([10.190.238.56]) by fmviesa007.fm.intel.com with ESMTP; 09 Mar 2026 00:31:01 -0700 From: Arun R Murthy Date: Mon, 09 Mar 2026 12:59:24 +0530 Subject: [PATCH RFC 1/3] drm/display/dp: Export function to wake the sink AUX_CH Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260309-dp_aux_timeout-v1-1-08c610a63a84@intel.com> References: <20260309-dp_aux_timeout-v1-0-08c610a63a84@intel.com> In-Reply-To: <20260309-dp_aux_timeout-v1-0-08c610a63a84@intel.com> To: Simona Vetter , Jani Nikula , ville.syrjala@linux.intel.com, suraj.kandpal@intel.com, imre.deak@intel.com Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, Arun R Murthy X-Mailer: b4 0.15-dev 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 --- 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/disp= lay/drm_dp_helper.c index a697cc227e28964cd8322803298178e7d788e820..1b8aa543ec3dc5819948af6f272= 4f3514b96b918 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, b= ool powered) } EXPORT_SYMBOL(drm_dp_dpcd_set_powered); =20 +/** + * 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 =3D 6; + u8 value =3D 0; + int ret =3D 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 =3D poll_timeout_us(ret =3D drm_dp_dpcd_readb(aux, DP_SET_POWER, &val= ue), + 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 =3D=3D 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 d= one * @aux: DisplayPort AUX channel diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_= dp_helper.h index 1d0acd58f48676f60ff6a07cc6812f72cbb452e8..933428025c4d75ab7a0aa63039e= d5f8e45ca625b 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; }; =20 +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); --=20 2.25.1