From patchwork Tue Mar 22 14:38:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 12788595 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 3CD95C433EF for ; Tue, 22 Mar 2022 14:38:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7376710E564; Tue, 22 Mar 2022 14:38:50 +0000 (UTC) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id BD1B910E563; Tue, 22 Mar 2022 14:38:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647959928; x=1679495928; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=CGHl0QRl/mxDKKqcRNMnrRDk2PYQtNi8ZfaGKpy2LIs=; b=J3vyPshM3+JpfjUK5WjhYPlzWhjZODUf8ix4pqg9MyQdX574MxocKyXy N4ikM1ca6i0n4nxeOu6Zpt07EcVbRSQmUPN153jbXYLCT1gKL3uQo/sq/ gUoNvvHMgfe6qBR6QO/ACRQ9qWAzIlADlXm9KwyGDC+1FrWBQ7Xn73tcU uyb6d4lUfc3cds5cpfYruGx/18Jb7mjnvW75kSiaPBHNpqTWQA/aY1XcN RPsnldZikETQAlhhkIJ87hb46VNWD2RN8HtyiXbP0G7ZuM3iIVm8csqYA 7c4cPdVczB8KoUNFfs2zRnJkOkDS60slNnjfBc0OlpeH6vnSKb1fz5o34 A==; X-IronPort-AV: E=McAfee;i="6200,9189,10293"; a="238436189" X-IronPort-AV: E=Sophos;i="5.90,201,1643702400"; d="scan'208";a="238436189" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2022 07:38:48 -0700 X-IronPort-AV: E=Sophos;i="5.90,201,1643702400"; d="scan'208";a="543714823" Received: from ideak-desk.fi.intel.com ([10.237.72.175]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2022 07:38:46 -0700 From: Imre Deak To: intel-gfx@lists.freedesktop.org Subject: [PATCH v2] drm/i915: Add a DP1.2 compatible way to read LTTPR capabilities Date: Tue, 22 Mar 2022 16:38:44 +0200 Message-Id: <20220322143844.42616-1-imre.deak@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220228201234.1448613-1-imre.deak@intel.com> References: <20220228201234.1448613-1-imre.deak@intel.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dri-devel@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" At least some DELL monitors (P2715Q) with DPCD_REV 1.2 return corrupted DPCD register values when reading from the 0xF0000- LTTPR range with an AUX transaction block size bigger than 1. The DP standard requires 0 to be returned - as for any other reserved/invalid addresses - but these monitors return the DPCD_REV register value repeated in each byte of the read buffer. This will in turn corrupt the values returned by the LTTPRs between the source and the monitor: LTTPRs must adjust the values they read from the downstream DPRX, for instance left-shift/init the downstream DP_PHY_REPEATER_CNT value. Since the value returned by the monitor's DPRX is non-zero the adjusted values will be corrupt. Reading the LTTPR registers one-by-one instead of reading all of them with a single AUX transfer works around the issue. According to the DP standard's 0xF0000 register description: "LTTPR-related registers at DPCD Addresses F0000h through F02FFh are valid only for DPCD r1.4 (or higher)." While it's unclear if DPCD r1.4 refers to the DPCD_REV or to the LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV register (tickets filed at the VESA site to clarify this haven't been addressed), one possibility is that it's a restriction due to non-compliant monitors described above. Disabling the non-transparent LTTPR mode for all such monitors is not a viable solution: the transparent LTTPR mode has its own issue causing link training failures and this would affect a lot of monitors in use with DPCD_REV < 1.4. Instead this patch works around the problem by reading the LTTPR common and PHY cap registers one-by-one for any monitor with a DPCD_REV < 1.4. The standard requires the DPCD capabilites to be read after the LTTPR common capabilities are read, so re-read the DPCD capabilities after the LTTPR common and PHY caps were read out. v2: - Use for instead of a while loop. (Ville) - Add to code comment the monitor model with the problem. Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4531 Cc: Ville Syrjälä Signed-off-by: Imre Deak Reviewed-by: Ville Syrjälä --- drivers/gpu/drm/dp/drm_dp.c | 57 ++++++++++++------- .../drm/i915/display/intel_dp_link_training.c | 30 +++++++--- include/drm/dp/drm_dp_helper.h | 2 + 3 files changed, 58 insertions(+), 31 deletions(-) diff --git a/drivers/gpu/drm/dp/drm_dp.c b/drivers/gpu/drm/dp/drm_dp.c index 703972ae14c64..58744f83931af 100644 --- a/drivers/gpu/drm/dp/drm_dp.c +++ b/drivers/gpu/drm/dp/drm_dp.c @@ -2390,9 +2390,35 @@ int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_S } EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs); +static int drm_dp_read_lttpr_regs(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE], int address, + u8 *buf, int buf_size) +{ + /* + * At least the DELL P2715Q monitor with a DPCD_REV < 0x14 returns + * corrupted values when reading from the 0xF0000- range with a block + * size bigger than 1. + */ + int block_size = dpcd[DP_DPCD_REV] < 0x14 ? 1 : buf_size; + int offset; + int ret; + + for (offset = 0; offset < buf_size; offset += block_size) { + ret = drm_dp_dpcd_read(aux, + address + offset, + &buf[offset], block_size); + if (ret < 0) + return ret; + + WARN_ON(ret != block_size); + } + + return 0; +} + /** * drm_dp_read_lttpr_common_caps - read the LTTPR common capabilities * @aux: DisplayPort AUX channel + * @dpcd: DisplayPort configuration data * @caps: buffer to return the capability info in * * Read capabilities common to all LTTPRs. @@ -2400,25 +2426,19 @@ EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs); * Returns 0 on success or a negative error code on failure. */ int drm_dp_read_lttpr_common_caps(struct drm_dp_aux *aux, + const u8 dpcd[DP_RECEIVER_CAP_SIZE], u8 caps[DP_LTTPR_COMMON_CAP_SIZE]) { - int ret; - - ret = drm_dp_dpcd_read(aux, - DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV, - caps, DP_LTTPR_COMMON_CAP_SIZE); - if (ret < 0) - return ret; - - WARN_ON(ret != DP_LTTPR_COMMON_CAP_SIZE); - - return 0; + return drm_dp_read_lttpr_regs(aux, dpcd, + DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV, + caps, DP_LTTPR_COMMON_CAP_SIZE); } EXPORT_SYMBOL(drm_dp_read_lttpr_common_caps); /** * drm_dp_read_lttpr_phy_caps - read the capabilities for a given LTTPR PHY * @aux: DisplayPort AUX channel + * @dpcd: DisplayPort configuration data * @dp_phy: LTTPR PHY to read the capabilities for * @caps: buffer to return the capability info in * @@ -2427,20 +2447,13 @@ EXPORT_SYMBOL(drm_dp_read_lttpr_common_caps); * Returns 0 on success or a negative error code on failure. */ int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux, + const u8 dpcd[DP_RECEIVER_CAP_SIZE], enum drm_dp_phy dp_phy, u8 caps[DP_LTTPR_PHY_CAP_SIZE]) { - int ret; - - ret = drm_dp_dpcd_read(aux, - DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER(dp_phy), - caps, DP_LTTPR_PHY_CAP_SIZE); - if (ret < 0) - return ret; - - WARN_ON(ret != DP_LTTPR_PHY_CAP_SIZE); - - return 0; + return drm_dp_read_lttpr_regs(aux, dpcd, + DP_TRAINING_AUX_RD_INTERVAL_PHY_REPEATER(dp_phy), + caps, DP_LTTPR_PHY_CAP_SIZE); } EXPORT_SYMBOL(drm_dp_read_lttpr_phy_caps); 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 5d98773efd1b3..fbee20a76cf44 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c @@ -55,6 +55,7 @@ static u8 *intel_dp_lttpr_phy_caps(struct intel_dp *intel_dp, } static void intel_dp_read_lttpr_phy_caps(struct intel_dp *intel_dp, + const u8 dpcd[DP_RECEIVER_CAP_SIZE], enum drm_dp_phy dp_phy) { struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base; @@ -63,7 +64,7 @@ static void intel_dp_read_lttpr_phy_caps(struct intel_dp *intel_dp, intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name)); - if (drm_dp_read_lttpr_phy_caps(&intel_dp->aux, dp_phy, phy_caps) < 0) { + if (drm_dp_read_lttpr_phy_caps(&intel_dp->aux, dpcd, dp_phy, phy_caps) < 0) { drm_dbg_kms(&dp_to_i915(intel_dp)->drm, "[ENCODER:%d:%s][%s] failed to read the PHY caps\n", encoder->base.base.id, encoder->base.name, phy_name); @@ -77,10 +78,11 @@ static void intel_dp_read_lttpr_phy_caps(struct intel_dp *intel_dp, phy_caps); } -static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp) +static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp, const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base; struct drm_i915_private *i915 = to_i915(encoder->base.dev); + int ret; if (intel_dp_is_edp(intel_dp)) return false; @@ -92,8 +94,9 @@ static bool intel_dp_read_lttpr_common_caps(struct intel_dp *intel_dp) if (DISPLAY_VER(i915) < 10 || IS_GEMINILAKE(i915)) return false; - if (drm_dp_read_lttpr_common_caps(&intel_dp->aux, - intel_dp->lttpr_common_caps) < 0) + ret = drm_dp_read_lttpr_common_caps(&intel_dp->aux, dpcd, + intel_dp->lttpr_common_caps); + if (ret < 0) goto reset_caps; drm_dbg_kms(&dp_to_i915(intel_dp)->drm, @@ -122,14 +125,14 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable) return drm_dp_dpcd_write(&intel_dp->aux, DP_PHY_REPEATER_MODE, &val, 1) == 1; } -static int intel_dp_init_lttpr(struct intel_dp *intel_dp) +static int intel_dp_init_lttpr(struct intel_dp *intel_dp, const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base; struct drm_i915_private *i915 = to_i915(encoder->base.dev); int lttpr_count; int i; - if (!intel_dp_read_lttpr_common_caps(intel_dp)) + if (!intel_dp_read_lttpr_common_caps(intel_dp, dpcd)) return 0; lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps); @@ -168,7 +171,7 @@ static int intel_dp_init_lttpr(struct intel_dp *intel_dp) } for (i = 0; i < lttpr_count; i++) - intel_dp_read_lttpr_phy_caps(intel_dp, DP_PHY_LTTPR(i)); + intel_dp_read_lttpr_phy_caps(intel_dp, dpcd, DP_PHY_LTTPR(i)); return lttpr_count; } @@ -193,9 +196,18 @@ static int intel_dp_init_lttpr(struct intel_dp *intel_dp) */ int intel_dp_init_lttpr_and_dprx_caps(struct intel_dp *intel_dp) { - int lttpr_count = intel_dp_init_lttpr(intel_dp); + u8 dpcd[DP_RECEIVER_CAP_SIZE]; + int lttpr_count; - /* The DPTX shall read the DPRX caps after LTTPR detection. */ + if (drm_dp_read_dpcd_caps(&intel_dp->aux, dpcd)) + return -EIO; + + lttpr_count = intel_dp_init_lttpr(intel_dp, dpcd); + + /* + * The DPTX shall read the DPRX caps after LTTPR detection, so re-read + * it here. + */ if (drm_dp_read_dpcd_caps(&intel_dp->aux, intel_dp->dpcd)) { intel_dp_reset_lttpr_common_caps(intel_dp); return -EIO; diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h index 51e02cf75277e..1eccd97419436 100644 --- a/include/drm/dp/drm_dp_helper.h +++ b/include/drm/dp/drm_dp_helper.h @@ -2148,8 +2148,10 @@ bool drm_dp_read_sink_count_cap(struct drm_connector *connector, int drm_dp_read_sink_count(struct drm_dp_aux *aux); int drm_dp_read_lttpr_common_caps(struct drm_dp_aux *aux, + const u8 dpcd[DP_RECEIVER_CAP_SIZE], u8 caps[DP_LTTPR_COMMON_CAP_SIZE]); int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux, + const u8 dpcd[DP_RECEIVER_CAP_SIZE], enum drm_dp_phy dp_phy, u8 caps[DP_LTTPR_PHY_CAP_SIZE]); int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);