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=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 4EA2CC0044C for ; Mon, 5 Nov 2018 06:25:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1073920831 for ; Mon, 5 Nov 2018 06:25:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="Jch0orA/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1073920831 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 S1729378AbeKEPnZ (ORCPT ); Mon, 5 Nov 2018 10:43:25 -0500 Received: from fllv0016.ext.ti.com ([198.47.19.142]:36020 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729321AbeKEPnZ (ORCPT ); Mon, 5 Nov 2018 10:43:25 -0500 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id wA56PBCB035927; Mon, 5 Nov 2018 00:25:11 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1541399111; bh=0PppT9mIaehdR4ZaC0+tEzCfp+TKjPHiJwNnjg6c5WY=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=Jch0orA/z5rv2CM5RY+A/+eh6BA4An5lNM7ID1FAW3HxSipxV1sLUmNx1NlRMsESN CDLF+4E4Iz5WnZXj42+Yzza6rQNMO4pPdsfVplo1s9sLdKMpfoCOePXd+xX6b9Vgp4 1bXBziHKczc4gG1alFe4oCyigZPVv7rFNAxPWtZo= Received: from DLEE104.ent.ti.com (dlee104.ent.ti.com [157.170.170.34]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id wA56PB8P036073 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 5 Nov 2018 00:25:11 -0600 Received: from DLEE110.ent.ti.com (157.170.170.21) by DLEE104.ent.ti.com (157.170.170.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3; Mon, 5 Nov 2018 00:25:11 -0600 Received: from dlep32.itg.ti.com (157.170.170.100) by DLEE110.ent.ti.com (157.170.170.21) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1466.3 via Frontend Transport; Mon, 5 Nov 2018 00:25:11 -0600 Received: from [172.24.190.215] (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id wA56P8Fp031313; Mon, 5 Nov 2018 00:25:08 -0600 Subject: Re: [PATCH 1/6] phy: Add max_bitrate attribute & phy_get_max_bitrate() To: Marc Kleine-Budde , , , , CC: , , , References: <20181102192616.28291-1-faiz_abbas@ti.com> <20181102192616.28291-2-faiz_abbas@ti.com> <5e1a0b67-510a-5512-d477-0b363e4733fe@pengutronix.de> From: Faiz Abbas Message-ID: Date: Mon, 5 Nov 2018 11:57:41 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <5e1a0b67-510a-5512-d477-0b363e4733fe@pengutronix.de> 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 Hi Marc, On Saturday 03 November 2018 03:06 PM, Marc Kleine-Budde wrote: > On 11/02/2018 08:26 PM, Faiz Abbas wrote: >> In some subsystems (eg. CAN) the physical layer capabilities are >> the limiting factor in the datarate of the device. Typically, the >> physical layer transceiver does not provide a way to discover this >> limitation at runtime. Thus this information needs to be represented as >> a phy attribute which is read from the device tree. >> >> Therefore, add an optional max_bitrate attribute to the generic phy >> sybsystem. Also add the complementary API which enables the consumer >> to get max_bitrate. >> >> Signed-off-by: Faiz Abbas > > NACK - We already have such a functionality in the CAN subsystem. > Please have a look at the patches: > > e759c626d826 can: m_can: Support higher speed CAN-FD bitrates > b54f9eea7667 dt-bindings: can: m_can: Document new can transceiver binding > 2290aefa2e90 can: dev: Add support for limiting configured bitrate > 54a7fbcc17bc dt-bindings: can: can-transceiver: Document new binding > I remove the transceiver child node binding documentation in patch 5/6. The existing implementation is pretty limiting as it just has a child node with no associated device. What if a transceiver requires its own configurations before it can start sending/receiving messages (for example, my usecase requires it to pull the standby line low)? I think that can be solved by implementing the transceiver as a phy and exposing a generic get_max_bitrate API. That way, the transceiver device can do all its startup configuration in the phy probe function. In any case, do suggest if you have a better idea on how to implement pull gpio low requirement. Thanks, Faiz