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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 055FCC11D0C for ; Thu, 20 Feb 2020 19:28:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2FA2208C4 for ; Thu, 20 Feb 2020 19:28:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="LAPmdFJ/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728952AbgBTT2j (ORCPT ); Thu, 20 Feb 2020 14:28:39 -0500 Received: from fllv0015.ext.ti.com ([198.47.19.141]:53048 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728596AbgBTT2j (ORCPT ); Thu, 20 Feb 2020 14:28:39 -0500 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 01KJRs19059352; Thu, 20 Feb 2020 13:27:54 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1582226874; bh=bQZBs4R8I7SS5K4xnJzvOySpsb0IN5aljouYPVfbqJE=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=LAPmdFJ/We64GPO2f7Rw7VcZ6mNHuZ8mOvNP8+YMK6vVjiz4Lfz1fHEY5hY3YoZC6 Gn3VDyX0J1d8jdHfhwBQh2U2ey+p55+j9TsGwLa8MZ7+V8rggIlD/qyQWZ1ym9Rpen z+pM99r/DaxeHvY12codHvrgMvR0gDlCIgSTq6Bc= Received: from DLEE100.ent.ti.com (dlee100.ent.ti.com [157.170.170.30]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTP id 01KJRsfB000862; Thu, 20 Feb 2020 13:27:54 -0600 Received: from DLEE105.ent.ti.com (157.170.170.35) by DLEE100.ent.ti.com (157.170.170.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Thu, 20 Feb 2020 13:27:54 -0600 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE105.ent.ti.com (157.170.170.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Thu, 20 Feb 2020 13:27:54 -0600 Received: from [128.247.59.107] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 01KJRdtc041257; Thu, 20 Feb 2020 13:27:39 -0600 Subject: Re: [PATCH] ASoC: tas2562: Add support for digital volume control To: Mark Brown CC: , , , , References: <20200220172721.10547-1-dmurphy@ti.com> <20200220184507.GF3926@sirena.org.uk> <20200220191803.GH3926@sirena.org.uk> From: Dan Murphy Message-ID: <6f3ff810-5e75-cb33-10d6-198a7c5cd202@ti.com> Date: Thu, 20 Feb 2020 13:22:34 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200220191803.GH3926@sirena.org.uk> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mark On 2/20/20 1:18 PM, Mark Brown wrote: > On Thu, Feb 20, 2020 at 12:46:57PM -0600, Dan Murphy wrote: >> On 2/20/20 12:45 PM, Mark Brown wrote: >>> Is there a reason not to use the chip default here? Otherwise this >>> looks good. >> Chip default is set to 0dB full blast+ 0x40400000.  This sets the volume to >> -110dB. > OK... that's a policy decision the same as all other volume changes and > so shouldn't be done by the driver - as ever we don't know how the > system is set up and what values make sense and keeping things out of > the driver means we don't end up with competing system integration > decisions causing changes in the driver. The system may have an > external amplifier they prefer to use for hardware volume control, may > prefer to do entirely soft volume control in their sound server or > something like that. But this is an amplifier.  Not sure why the system designer would design cascading amplifiers. And if that was the case wouldn't you want the output to be low so you don't overdrive the ext amplifier front end? I mean I have no qualms with removing the init from the driver. I will send v3 tomorrow after a 24 hour review cycle. I was considering safety in that the device is on at full blast (not sure why the HW is defaulted that way but it is). But if volume is adjusted prior to playback then this is not an issue.  But if volume is not adjusted then it plays full blast. Dan