From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 D0BAF13C67E; Thu, 6 Mar 2025 12:32:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741264335; cv=none; b=eDiirLh5/3pb7XXHDzfboebaKaN7XvoO1iXmbkDcV2Owi7XXhgZeJTTrPnjh/a/3cQ/1YDaceJqm05PiY35suJEpKYJXlCwtJga1+pMVko24Ctsq4X+VMl1oFumDhPHmM32lzbqSRiO9dUMAR06+WeYS5K4GnWOiwQO2KkkSvkE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741264335; c=relaxed/simple; bh=oy4+bcRMMxQbh/qp4MXWjzg4Vg1yhmrjLtOiLO41T6c=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=RgHpus9HTMyCgGi3q7v93Gqydeaq0WbS3rk7QN+XolXPPL+q6bZ31K3epvpGIztEN4TEBHBmmx5hUDPvuVaylzV+FeFvt0YdCPw6nMYWzRn03ngW0vFhCsb2ZYRkPtrlOM30i3ZuMtH6UPocPqCBXuGE+gngSVy6d6WwCqiCjnA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=MxsQ6FX8; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="MxsQ6FX8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1741264333; x=1772800333; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=oy4+bcRMMxQbh/qp4MXWjzg4Vg1yhmrjLtOiLO41T6c=; b=MxsQ6FX8iMSd/DaAc5j2BfOqXgnynMZhIQ1KroGFo9ieozGT/EZxBPXt 5YRyc/sNzG5vql6EzKhrFPiW0ZC5mBI31DhfXeiWkg77QHARzJ3zYZKFy WANVc974pq2MPdZiC1N9Co2qWkS+Z/LOg3IJeG+gVRPf2s0CkfYx58Vlr X55Q3bocigUzn0LS6A1+Tz8vSgidPrMtrY+Dszth7heQYiARj6LhQbcec Vpj9lPOiqYfZ/wLoSre2fXHl/MW2kdVKjlA2aYgFN3aYt2TFNxP6PfvDS 5SWA7i69/pqgdQNkItjZBle6mOYul/WDBjfse3Aa0uRT0+lkGqJWMPzTn g==; X-CSE-ConnectionGUID: wqwiyAw/Tse03AGyg34u4Q== X-CSE-MsgGUID: hfdOx84uS0qXl/82luPWUg== X-IronPort-AV: E=McAfee;i="6700,10204,11363"; a="59815054" X-IronPort-AV: E=Sophos;i="6.14,226,1736841600"; d="scan'208";a="59815054" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2025 04:32:12 -0800 X-CSE-ConnectionGUID: YmCqY4ujQDa8dAipYWTt6Q== X-CSE-MsgGUID: CmcuiUPlQemGc3evzetPjg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,226,1736841600"; d="scan'208";a="149790584" Received: from unknown (HELO localhost) ([10.237.66.160]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2025 04:32:07 -0800 From: Jani Nikula To: Dmitry Baryshkov , Lyude Paul , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Clark , Abhinav Kumar , Sean Paul , Marijn Suijten Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org Subject: Re: [PATCH RFC v2 0/7] drm/display: dp: add new DPCD access functions In-Reply-To: <20250301-drm-rework-dpcd-access-v2-0-4d92602fc7cd@linaro.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20250301-drm-rework-dpcd-access-v2-0-4d92602fc7cd@linaro.org> Date: Thu, 06 Mar 2025 14:32:04 +0200 Message-ID: <87a59ywda3.fsf@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Sat, 01 Mar 2025, Dmitry Baryshkov wrote: > Existing DPCD access functions return an error code or the number of > bytes being read / write in case of partial access. However a lot of > drivers either (incorrectly) ignore partial access or mishandle error > codes. In other cases this results in a boilerplate code which compares > returned value with the size. > > As suggested by Jani implement new set of DPCD access helpers, which > ignore partial access, always return 0 or an error code. Reimplement > existing helpers using the new functions to ensure backwards > compatibility. I think that description is for earlier versions of the series, it's the other way round now. Regardless, glanced through the series quickly, I like it, this is Acked-by: Jani Nikula > > This series targets only the DRM helpers code. If the approach is found > to be acceptable, each of the drivers should be converted on its own. > > Signed-off-by: Dmitry Baryshkov > --- > Changes in v2: > - Reimplemented new helpers using old ones (Lyude) > - Reworked the drm_dp_dpcd_read_link_status() patch (Lyude) > - Dropped the dp-aux-dev patch (Jani) > - Link to v1: https://lore.kernel.org/r/20250117-drm-rework-dpcd-access-v1-0-7fc020e04dbc@linaro.org > > --- > Dmitry Baryshkov (7): > drm/display: dp: implement new access helpers > drm/display: dp: change drm_dp_dpcd_read_link_status() return value > drm/display: dp: use new DCPD access helpers > drm/display: dp-aux-dev: use new DCPD access helpers > drm/display: dp-cec: use new DCPD access helpers > drm/display: dp-mst-topology: use new DCPD access helpers > drm/display: dp-tunnel: use new DCPD access helpers > > drivers/gpu/drm/amd/amdgpu/atombios_dp.c | 8 +- > .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +- > drivers/gpu/drm/display/drm_dp_aux_dev.c | 12 +- > drivers/gpu/drm/display/drm_dp_cec.c | 37 ++- > drivers/gpu/drm/display/drm_dp_helper.c | 307 +++++++++------------ > drivers/gpu/drm/display/drm_dp_mst_topology.c | 105 ++++--- > drivers/gpu/drm/display/drm_dp_tunnel.c | 20 +- > drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c | 4 +- > drivers/gpu/drm/msm/dp/dp_ctrl.c | 24 +- > drivers/gpu/drm/msm/dp/dp_link.c | 18 +- > drivers/gpu/drm/radeon/atombios_dp.c | 8 +- > include/drm/display/drm_dp_helper.h | 92 +++++- > 12 files changed, 322 insertions(+), 315 deletions(-) > --- > base-commit: c0eb65494e59d9834af7cbad983629e9017b25a1 > change-id: 20241231-drm-rework-dpcd-access-b0fc2e47d613 > > Best regards, -- Jani Nikula, Intel