From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 375FD79DC; Sat, 30 Dec 2023 12:00:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DC9Ur/nm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CB62C433C8; Sat, 30 Dec 2023 12:00:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1703937650; bh=mt+RDhVkwVPW4X5LRtr6G22nbNkFNAmMmpwaLPfSfTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DC9Ur/nmpiKgxep0xcGyI24Y005AvrdZGYM/ZuGJw4tS/l/YGSIxKSlrzQ2LzA1C5 uQf+L5m5ti5T9AIeQ3eFfYtZ2mFIdD2Dmt3SGxZReKfT6jg39XC4sEozB/gr9jglyL HGismKdrJnrJTm3E2V6SqnVjlJ1LjmfPSLOFyoGA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Animesh Manna , Uma Shankar , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Jani Nikula , Sasha Levin Subject: [PATCH 6.6 010/156] drm/i915/edp: dont write to DP_LINK_BW_SET when using rate select Date: Sat, 30 Dec 2023 11:57:44 +0000 Message-ID: <20231230115812.701902401@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231230115812.333117904@linuxfoundation.org> References: <20231230115812.333117904@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jani Nikula [ Upstream commit e6861d8264cd43c5eb20196e53df36fd71ec5698 ] The eDP 1.5 spec adds a clarification for eDP 1.4x: > For eDP v1.4x, if the Source device chooses the Main-Link rate by way > of DPCD 00100h, the Sink device shall ignore DPCD 00115h[2:0]. We write 0 to DP_LINK_BW_SET (DPCD 100h) even when using DP_LINK_RATE_SET (DPCD 114h). Stop doing that, as it can cause the panel to ignore the rate set method. Moreover, 0 is a reserved value for DP_LINK_BW_SET, and should not be used. v2: Improve the comments (Ville) Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9081 Tested-by: Animesh Manna Reviewed-by: Uma Shankar Cc: Ville Syrjälä Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20231205180551.2476228-1-jani.nikula@intel.com (cherry picked from commit 23b392b94acb0499f69706c5808c099f590ebcf4) Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula Signed-off-by: Sasha Levin --- .../drm/i915/display/intel_dp_link_training.c | 31 +++++++++++++------ 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c index d09e43a38fa61..a62bca622b0a1 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c @@ -650,19 +650,30 @@ intel_dp_update_link_bw_set(struct intel_dp *intel_dp, const struct intel_crtc_state *crtc_state, u8 link_bw, u8 rate_select) { - u8 link_config[2]; + u8 lane_count = crtc_state->lane_count; - /* Write the link configuration data */ - link_config[0] = link_bw; - link_config[1] = crtc_state->lane_count; if (crtc_state->enhanced_framing) - link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; - drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2); + lane_count |= DP_LANE_COUNT_ENHANCED_FRAME_EN; + + if (link_bw) { + /* DP and eDP v1.3 and earlier link bw set method. */ + u8 link_config[] = { link_bw, lane_count }; - /* eDP 1.4 rate select method. */ - if (!link_bw) - drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET, - &rate_select, 1); + drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, + ARRAY_SIZE(link_config)); + } else { + /* + * eDP v1.4 and later link rate set method. + * + * eDP v1.4x sinks shall ignore DP_LINK_RATE_SET if + * DP_LINK_BW_SET is set. Avoid writing DP_LINK_BW_SET. + * + * eDP v1.5 sinks allow choosing either, and the last choice + * shall be active. + */ + drm_dp_dpcd_writeb(&intel_dp->aux, DP_LANE_COUNT_SET, lane_count); + drm_dp_dpcd_writeb(&intel_dp->aux, DP_LINK_RATE_SET, rate_select); + } } /* -- 2.43.0