From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2432626-1519637656-2-15236263444622267282 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='com', MailFrom='org', XOriginatingCountry='UNK' X-Spam-charsets: plain='utf-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-serial-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1519637655; b=DdYoPJBMtkaGwHzBu1kkOYAhi+GzL4fQZQ3VrdojasTwGP0 7Aee7Quurnyw/5IQchZapwJ8gAXFUFdf/qWLbE4hU9DXsM0XmZ/3a9kQEe42aPLq 8Hwvvuv2NP9xGZHmKXwUCXb0Kp9qvBb9KwpPOzVXh54yRgI3+3VuY/4TwhNIlnny nkxKf+k7DW7e6mUkkH8BXwG+9XTRo2rkuklAub9VMiQMGkXQ075/Tx+VTfE1fv82 6HVgmyD1wE9kvVEDyfa9lcxSEErC2QZ0GUByyluM1NcccgIbJpBq7DT/GMfBrfCv OQydTKCeeliFPLD1RoIRBWiW5PG4h2ZXlowVCsQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=subject:to:references:cc:from:message-id :date:mime-version:in-reply-to:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1519637655; bh=A/2okSQjszUooOQcPA1Hyv5AF+9VIQrkxJqDAo4OFt8=; b=P oSLg3FI9OAkGMZLNBCIL83ExEYXUztbkM35IFWxNPdxLXC/AH29SCZz4cA0MjAY5 WEnBe1agVXtSaz3fcTxvB+zaph6tcRiwj7nExeS2e0/N/fkQmGmvXRq/xQMEojnf s5q4U2xtx0O/Izs2+mUlkQedl5R1EO/w7HaW9VOHY9NB70RzLCHkT+I1eGz2MQYJ NwIRQzhqO/yhPmKTK+VXW4+nJ+bs36g8qebjBMC/jrpe3Msgdn3TCiVJo+8QWXaj gAbRDEDnbtamCYNp2o8NkpQlyRcaVmx7FkEx/jkiKR4PE4/y1ml9hDxjbquRavZg 0ZISlseK4LQGJcTpMqg8A== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=huawei.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-serial-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=huawei.com header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=huawei.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-serial-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=huawei.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbeBZJeN (ORCPT ); Mon, 26 Feb 2018 04:34:13 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:33565 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751022AbeBZJeN (ORCPT ); Mon, 26 Feb 2018 04:34:13 -0500 Subject: Re: [RFC PATCH 0/2] serial: 8250_dw: IO space + polling mode support To: Andy Shevchenko , , , , , , References: <1519324923-196857-1-git-send-email-john.garry@huawei.com> <1519381801.10722.103.camel@linux.intel.com> <3c4c5f58-a661-13c8-cc1c-8d43828982cb@huawei.com> <1519407117.10722.124.camel@linux.intel.com> CC: , , From: John Garry Message-ID: <88214a3e-82cc-c931-804c-7dc90fb8721f@huawei.com> Date: Mon, 26 Feb 2018 09:33:51 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <1519407117.10722.124.camel@linux.intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.238] X-CFilter-Loop: Reflected Sender: linux-serial-owner@vger.kernel.org X-Mailing-List: linux-serial@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 23/02/2018 17:31, Andy Shevchenko wrote: > On Fri, 2018-02-23 at 11:02 +0000, John Garry wrote: >> On 23/02/2018 10:30, Andy Shevchenko wrote: >>> On Fri, 2018-02-23 at 02:42 +0800, John Garry wrote: >>>> There is a requirement >> >>> Where? >> Hi Andy, >> We require it for a development board for our hip06 platform. > > Okay, and this particular platform uses Synopsys IP? As I see this uart is really a virtual 8250, so HW details like apb clocks and the like are hidden, so may not be relevant. However I will check with the BMC team to know the specific details. > >>>> for supporting an 8250-compatible UART with >>>> the following profile/features: >>>> - platform device >>>> - polling mode (i.e. no interrupt support) >>>> - ACPI FW >>> >>> Elaborate this one, please. >> >> So we need to define our own HID here, and cannot use PNP compatible >> CID >> (like PNP0501) as we cannot use the 8250 PNP driver. > > Why not? What are the impediments? > To support the host controller for this device, we will create an MFD, i.e. platform device, per slave device. >> This is related to the Hisi LPC ACPI support, where we would create >> an >> MFD (i.e. platform device) for the UART. > > Why you can't do properly in ACPI? > >>>> - IO port iotype >>>> - 16550-compatible >>>> >>>> For OF, we have 8250_of.c, and for PNP device we have 8250_pnp.c >>>> drivers. However there does not seem to any driver satisfying >>>> the above requirements. So this RFC is to find opinion on >>>> modifying the Synopsys DW 8250_dw.c driver to support these >>>> generic features. >>> >>> Synopsys 8250 is a particular case of platform drivers. It doesn't >>> satisfy "8250-compatible UART" requirement. > >> Right, but I wanted to try to use the generic parts of the driver to >> support this UART to save writing yet another driver. > > It's still odd. Why this one, why not 8250_foo_bar to touch instead? > Agreed, it's odd. I choose as 8250_dw.c as it has ACPI support already. And I recognise the hw from popularity. No stronger reasons than that. Thanks, John