From patchwork Sat May 6 18:04:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Kai-Heng Feng X-Patchwork-Id: 1778070 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=canonical.com header.i=@canonical.com header.a=rsa-sha256 header.s=20210705 header.b=GzhwilaM; dkim-atps=neutral Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4QDFp42bvfz214P for ; Sun, 7 May 2023 04:05:14 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1pvMHI-0001VR-0J; Sat, 06 May 2023 18:05:04 +0000 Received: from smtp-relay-canonical-1.internal ([10.131.114.174] helo=smtp-relay-canonical-1.canonical.com) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1pvMHG-0001VB-Bs for kernel-team@lists.ubuntu.com; Sat, 06 May 2023 18:05:02 +0000 Received: from localhost.localdomain (unknown [10.101.196.174]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPSA id AFC0342A31 for ; Sat, 6 May 2023 18:05:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1683396302; bh=WmaO5unT5A1tgDx4Qy/oLA1u3C4QCq7g10m9Ba5gabA=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=GzhwilaMwmN4/ubHGAY+xpv0N3F2OJypLRgaJ0MULO4BBFgk/lsP/7E7xf0HbMnz6 E7nQ+pEADcs+mR/7+0/uUGiToOQYHnfgRyXRpToORzzuthDoy0kwUJPF8ryMV591Pa GvxdpYLAsdy3nWLhEkLBZX7+obTmB1TsK2KvMI/wwckgRIR9vsud4MFjDrSe/sSPBi FnE8JcfmGHt5yhSuLMPgSkr4JG3F8F1TVn33JYgE5Pknx7uhS4jtSsf2mUmZSEJcbo pgV/QnMbpsiaNFL6otm+Lk77SYTTAomgdTxcqNnQGlGj1nrEhlBMyocqHAlTKHUgXE rAsctmoC6FB+w== From: Kai-Heng Feng To: kernel-team@lists.ubuntu.com Subject: [L] [PATCH 2/2] drm/i915: Explain the magic numbers for AUX SYNC/precharge length Date: Sat, 6 May 2023 20:04:09 +0200 Message-Id: <20230506180409.580489-3-kai.heng.feng@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230506180409.580489-1-kai.heng.feng@canonical.com> References: <20230506180409.580489-1-kai.heng.feng@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Ville Syrjälä BugLink: https://bugs.launchpad.net/bugs/2018655 Replace the hardcoded final numbers in the AUX SYNC/precharge setup, and derive those from numbers from the (e)DP specs. The new functions can serve as the single point of truth for the number of SYNC pulses we use. Cc: Jouni Högander Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20230329172434.18744-2-ville.syrjala@linux.intel.com Reviewed-by: Jouni Högander (cherry picked from commit 26bfc3f36f2104c174dfc72415547d5c28ef3f1c) Signed-off-by: Kai-Heng Feng --- drivers/gpu/drm/i915/display/intel_dp_aux.c | 32 +++++++++++++++++++-- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c index d5fed2eb66d2..f4b315b302da 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c @@ -120,6 +120,32 @@ static u32 skl_get_aux_clock_divider(struct intel_dp *intel_dp, int index) return index ? 0 : 1; } +static int intel_dp_aux_sync_len(void) +{ + int precharge = 16; /* 10-16 */ + int preamble = 16; + + return precharge + preamble; +} + +static int intel_dp_aux_fw_sync_len(void) +{ + int precharge = 16; /* 10-16 */ + int preamble = 8; + + return precharge + preamble; +} + +static int g4x_dp_aux_precharge_len(void) +{ + int precharge_min = 10; + int preamble = 16; + + /* HW wants the length of the extra precharge in 2us units */ + return (intel_dp_aux_sync_len() - + precharge_min - preamble) / 2; +} + static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp, int send_bytes, u32 aux_clock_divider) @@ -142,7 +168,7 @@ static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp, timeout | DP_AUX_CH_CTL_RECEIVE_ERROR | (send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) | - (3 << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) | + (g4x_dp_aux_precharge_len() << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) | (aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT); } @@ -166,8 +192,8 @@ 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(24) | - DP_AUX_CH_CTL_SYNC_PULSE_SKL(32); + DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(intel_dp_aux_fw_sync_len()) | + DP_AUX_CH_CTL_SYNC_PULSE_SKL(intel_dp_aux_sync_len()); if (intel_tc_port_in_tbt_alt_mode(dig_port)) ret |= DP_AUX_CH_CTL_TBT_IO;