From patchwork Mon Apr 11 13:25:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imre Deak X-Patchwork-Id: 12809102 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 691B2C433F5 for ; Mon, 11 Apr 2022 13:25:46 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BC6E210E2D0; Mon, 11 Apr 2022 13:25:45 +0000 (UTC) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 650E610E3D6; Mon, 11 Apr 2022 13:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649683544; x=1681219544; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=llxrA//BTM9nivqVRxdZEuenNFhdfez0LUACrQiAV+0=; b=BCMyCEcGthCcdisbdT7iT+oDIF8bq6OrRLi+U2es9+Ua5EEgnmHdq1Pu zw2OAxLvsD04Ebk0jvJ6vnGMG+6E4rKI0oZ6DY+0A8TpjDG10faVqBmVO ZG7y99eHqPsZBSbwmc6JZZGmZzQdnBT4f7TS1bPIlnVWCDt7d4TLfZM31 2XxKcBW1ftpWJ46Br/4TXenhuvTyXyvsz8BDvFHkSaMc85efTJrFki7XH XmmjIhzKxc3NRQlHU9Pf6D36Q2VKgq3/BccyhbCQmD5zWyDNQovYXPbRD SnFsNTGdDxOBk/ieZcSrH8ALhQwW8Z1MAjSjUV5JYWt4I6fH/q3plhX0z w==; X-IronPort-AV: E=McAfee;i="6400,9594,10313"; a="261552585" X-IronPort-AV: E=Sophos;i="5.90,251,1643702400"; d="scan'208";a="261552585" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2022 06:25:44 -0700 X-IronPort-AV: E=Sophos;i="5.90,251,1643702400"; d="scan'208";a="507109882" Received: from ideak-desk.fi.intel.com ([10.237.72.175]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Apr 2022 06:25:42 -0700 From: Imre Deak To: intel-gfx@lists.freedesktop.org Subject: [PATCH v3 1/2] drm/dp: Factor out a function to probe a DPCD address Date: Mon, 11 Apr 2022 16:25:39 +0300 Message-Id: <20220411132539.984647-1-imre.deak@intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220408172154.807900-1-imre.deak@intel.com> References: <20220408172154.807900-1-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, Khaled Almahallawy Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Factor out from drm_dp_dpcd_read() a function to probe a DPCD address with a 1-byte read access. This will be needed by the next patch doing a read from an LTTPR address, which must happen without the preceding wake-up read in drm_dp_dpcd_read(). While at it add tracing for the 1 byte read even if the read was successful. v2: Add a probe function instead of exporting drm_dp_dpcd_access(). (Jani) v3: Add tracing for the 1-byte read even if the read was successful. (Khaled) Cc: Jani Nikula Cc: Khaled Almahallawy Cc: dri-devel@lists.freedesktop.org Signed-off-by: Imre Deak Reviewed-by: Jani Nikula --- drivers/gpu/drm/dp/drm_dp.c | 33 ++++++++++++++++++++++++++++----- include/drm/dp/drm_dp_helper.h | 1 + 2 files changed, 29 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/dp/drm_dp.c b/drivers/gpu/drm/dp/drm_dp.c index 580016a1b9eb7..2a1f5ff6633cc 100644 --- a/drivers/gpu/drm/dp/drm_dp.c +++ b/drivers/gpu/drm/dp/drm_dp.c @@ -527,6 +527,31 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, return ret; } +/** + * drm_dp_dpcd_probe() - probe a given DPCD address with a 1-byte read access + * @aux: DisplayPort AUX channel (SST) + * @offset: address of the register to probe + * + * Probe the provided DPCD address by reading 1 byte from it. The function can + * be used to trigger some side-effect the read access has, like waking up the + * sink, without the need for the read-out value. + * + * Returns 0 if the read access suceeded, or a negative error code on failure. + */ +int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset) +{ + u8 buffer; + int ret; + + ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, &buffer, 1); + WARN_ON(ret == 0); + + drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, &buffer, ret); + + return ret < 0 ? ret : 0; +} +EXPORT_SYMBOL(drm_dp_dpcd_probe); + /** * drm_dp_dpcd_read() - read a series of bytes from the DPCD * @aux: DisplayPort AUX channel (SST or MST) @@ -559,10 +584,9 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, * monitor doesn't power down exactly after the throw away read. */ if (!aux->is_remote) { - ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, - buffer, 1); - if (ret != 1) - goto out; + ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV); + if (ret < 0) + return ret; } if (aux->is_remote) @@ -571,7 +595,6 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, size); -out: drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret); return ret; } diff --git a/include/drm/dp/drm_dp_helper.h b/include/drm/dp/drm_dp_helper.h index 1eccd97419436..91af98e6617c6 100644 --- a/include/drm/dp/drm_dp_helper.h +++ b/include/drm/dp/drm_dp_helper.h @@ -2053,6 +2053,7 @@ struct drm_dp_aux { bool is_remote; }; +int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset); ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, void *buffer, size_t size); ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,