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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D819DC43331 for ; Sat, 9 Nov 2019 11:18:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1D382196F for ; Sat, 9 Nov 2019 11:18:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573298318; bh=3Hq1uBKmbxWSyUaunSKUQp7cR6TxylIJ4pSQvHWS7Gc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Wv3Hgwkl9ybTv+OPA4WbLoBYP1TjsJpkSlScmNxmHqUXSdI+o+6WpmRv3Brk110Bm HcBTSE+5M6qHN0yrxeM+u8fejXqDfnmYTcL/nrULhYkWBYt7mYvcH648wtbOHY7BCQ 3ao32r1ieSESHnzk2NJWPnShqapUUpMn/dBQOmw8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726583AbfKILSh (ORCPT ); Sat, 9 Nov 2019 06:18:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:53666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726457AbfKILSh (ORCPT ); Sat, 9 Nov 2019 06:18:37 -0500 Received: from localhost (unknown [122.167.114.135]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 50EAD215EA; Sat, 9 Nov 2019 11:18:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573298316; bh=3Hq1uBKmbxWSyUaunSKUQp7cR6TxylIJ4pSQvHWS7Gc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kmkzuavN3jwaaLLRT3+0E5FSZqUBd4lnAoT85QaQgJf9A4jVzwLkitGq6sruZTxm5 0pJN/VBw++T0ED+sctbq7NZNXUkNgFhhfwts+gWVzXh6920GoXySLzM3nmtVcpnvp0 YeLxeZjdfbz304lHhZyrXUp0/dLvPWoHpJHkaP64= Date: Sat, 9 Nov 2019 16:48:23 +0530 From: Vinod Koul To: Pierre-Louis Bossart Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, tiwai@suse.de, broonie@kernel.org, gregkh@linuxfoundation.org, jank@cadence.com, srinivas.kandagatla@linaro.org, slawomir.blauciak@intel.com, Bard liao , Rander Wang , Ranjani Sridharan Subject: Re: [PATCH 0/3] soundwire: use UniqueID only when relevant Message-ID: <20191109111823.GD952516@vkoul-mobl> References: <20191022234808.17432-1-pierre-louis.bossart@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191022234808.17432-1-pierre-louis.bossart@linux.intel.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22-10-19, 18:48, Pierre-Louis Bossart wrote: > The hardware UniqueID, typically enabled with pin-strapping, is > required during enumeration to avoid conflicts between devices of the > same type. > > When there are no devices of the same type, using the UniqueID is > overkill and results in a lot of probe errors due to mismatches > between ACPI tables and hardware capabilities. For example it's not > uncommon for BIOS vendors to copy/paste the same settings between > platforms but the hardware pin-strapping is different. This is > perfectly legit and permitted by MIPI specs. > > With this patchset, the UniqueID is only used when multiple devices of > the same type are detected. The loop to detect multiple identical > devices is not super efficient but with typically fewer than 4 devices > per link there's no real incentive to be smarter. > > This change is only implemented for ACPI platforms, for DeviceTree > there is no change. I do not fully agree with the approach here but I do understand why this was done and do not have a better alternative, so applied now -- ~Vinod