From mboxrd@z Thu Jan 1 00:00:00 1970 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 DAD75C36010 for ; Tue, 1 Apr 2025 14:43:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6B58810E5E2; Tue, 1 Apr 2025 14:43:20 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="cOmAXulF"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8E67D10E5EB; Tue, 1 Apr 2025 14:43:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1743518600; x=1775054600; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=K6WJY3tfkFhz/muLLbEhJ7qHN/xkLBt2I7DVfEWfKWw=; b=cOmAXulFoWVJwxPq2MYzsUm42Ork1EhgE9efyl1BobzmKHU9xD61l2VQ 5CEG8vWkQcjg0A97ELr+eqEk6Z9YNKuFDKwWNikm7pyaFy9tGJKkL/T7x CkoPt8CcrfUJdpgpqOr1MvHO/Ck6RcClXBC6flZRS0da5LyUElEREA/BJ 9RY0dPtvAZXL3Yn2WvZ3lYcAi2HW9tfQ5y8KVez4H71dz8/17KoyKinQk XyKTRHQl3ZTNPQI5M2O4VYIN+myMQDQr4flKhGnftlF7J1FUNT9WKhMNv CV3Fb85kA/gfVI0AZf9FaoMfd619qowRZpj4KAyt2bpUlubN2HMGVS7k0 A==; X-CSE-ConnectionGUID: E/4GTyeOQsuo90sdZzycJA== X-CSE-MsgGUID: xpXoUQTORIWG+dzZsUeMUw== X-IronPort-AV: E=McAfee;i="6700,10204,11391"; a="44095946" X-IronPort-AV: E=Sophos;i="6.14,293,1736841600"; d="scan'208";a="44095946" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2025 07:43:19 -0700 X-CSE-ConnectionGUID: rfAdMOvnSAy03oJnx0kCmg== X-CSE-MsgGUID: 3ySWbYOHTWquYSPc0wG4Sw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,293,1736841600"; d="scan'208";a="131543480" Received: from ncintean-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.246.7]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Apr 2025 07:43:17 -0700 From: Jani Nikula To: Imre Deak , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Dmitry Baryshkov , Lyude Paul Subject: Re: [PATCH 1/2] drm/dp_mst: Fix GUID DPCD write to non-root MST branch devices In-Reply-To: <20250401103846.686408-1-imre.deak@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20250401103846.686408-1-imre.deak@intel.com> Date: Tue, 01 Apr 2025 17:43:13 +0300 Message-ID: <87ikno2b9a.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, 01 Apr 2025, Imre Deak wrote: > The return value on success of drm_dp_send_dpcd_write() called for > non-root MST branch devices from drm_dp_check_mstb_guid() is the number > of bytes transferred. Atm this return value (in case of a complete read) > will be regarded incorrectly as an error by the caller of > drm_dp_check_mstb_guid(). Fix this by converting the return value for a > complete read to the expected success code (0) and for a partial read to > a failure code (-EPROTO). > > Fixes: 2554da0de3e8 ("drm/display: dp-mst-topology: use new DCPD access helpers") > Cc: Dmitry Baryshkov > Cc: Lyude Paul > Signed-off-by: Imre Deak Reviewed-by: Jani Nikula > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index de3fc6090c906..619f461e02f76 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -2200,6 +2200,8 @@ static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, guid_t *guid) > ret = drm_dp_send_dpcd_write(mstb->mgr, > mstb->port_parent, > DP_GUID, sizeof(buf), buf); > + if (ret >= 0) > + ret = ret == sizeof(buf) ? 0 : -EPROTO; > } else { > ret = drm_dp_dpcd_write_data(mstb->mgr->aux, > DP_GUID, buf, sizeof(buf)); -- Jani Nikula, Intel