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=-1.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS autolearn=ham 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 935FAC43441 for ; Mon, 12 Nov 2018 22:05:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EE3C20896 for ; Mon, 12 Nov 2018 22:05:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="J92Axlr9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EE3C20896 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=ti.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730623AbeKMIAz (ORCPT ); Tue, 13 Nov 2018 03:00:55 -0500 Received: from lelv0143.ext.ti.com ([198.47.23.248]:48142 "EHLO lelv0143.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726006AbeKMIAy (ORCPT ); Tue, 13 Nov 2018 03:00:54 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id wACM5l06080446; Mon, 12 Nov 2018 16:05:47 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1542060347; bh=9hckHaMdViRwGn0p2SlgUshzdvUERuBAAETI6409DWs=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=J92Axlr9+7E/nHMilZeMrtF65NOOZHgtmPn8kq1EIWQEBJaXaCTdgClpgXnI3Ka+i WDUD5M0ls+3MT0BOP4iD10Jfzcj/90220emDAXlwgjhNm1Dk/qTKVdbHmX93uQNVyp Mmlq0quOcu6P/N6AxkFzAEipLQImZADuHRAFS5VA= Received: from DFLE105.ent.ti.com (dfle105.ent.ti.com [10.64.6.26]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id wACM5lCs013039 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 12 Nov 2018 16:05:47 -0600 Received: from DFLE102.ent.ti.com (10.64.6.23) by DFLE105.ent.ti.com (10.64.6.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3; Mon, 12 Nov 2018 16:05:47 -0600 Received: from dlep32.itg.ti.com (157.170.170.100) by DFLE102.ent.ti.com (10.64.6.23) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1466.3 via Frontend Transport; Mon, 12 Nov 2018 16:05:47 -0600 Received: from [128.247.59.203] (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id wACM5lKE009802; Mon, 12 Nov 2018 16:05:47 -0600 Subject: Re: [PATCH 1/2] opp: ti-opp-supply: Dynamically update u_volt_min To: "J, KEERTHY" , Viresh Kumar CC: , , , , , References: <1541565263-8296-1-git-send-email-j-keerthy@ti.com> <1541565263-8296-2-git-send-email-j-keerthy@ti.com> <20181108055401.btrixinlqcfh22du@vireshk-i7> From: Dave Gerlach Message-ID: Date: Mon, 12 Nov 2018 16:05:47 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit 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 On 11/11/2018 09:15 PM, J, KEERTHY wrote: > > > On 11/8/2018 11:24 AM, Viresh Kumar wrote: >> On 07-11-18, 10:04, Keerthy wrote: >>> The voltage range (min, max) provided in the device tree is from >>> the data manual and is pretty big, catering to a wide range of devices. >>> On a i2c read/write failure the regulator_set_voltage_triplet function >>> falls back to set voltage between min and max. The min value from Device >>> Tree can be lesser than the optimal value and in that case that can lead >>> to a hang or crash. Hence set the u_volt_min dynamically to the optimal >>> voltage value. >> >> And why shouldn't we fix the DT for this ? > > The DT voltages do not cater to the broad range of devices. In some > particular cases the DT min voltage is slightly lower the voltage at > which the device cannot sustain a particular frequency in which case the > device just silently hangs. So best thing to do is to actually read the > device specific voltages dynamically which will guarantee a particular > device sustaining a particular frequency at the optimal voltage. > Acked-by: Dave Gerlach >>