From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2611097-1519642483-2-4168895070966251217 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=1519642482; b=Wf0KqTBc/H6j5lqVdHN1SgD31dvVVZ+VNgAGoF7vFlBaRqo oe2GvzntzBCopepBS2oRX/Kb2RMiCYGoF1PjnMIiUOij3zuXsnGAeFVjmHjxYqJQ uUpnfHHaiK0sotattEOKsoMRh6MzOkTXKcNYZB/rsU4yYiFOLxIQhnPRL+D1pkgv 9whapIcOBT07bYuOfqiTbu50ajf/H/3pE0b+Xit8+bQnk4HKvTKGaUiiUdVBmlsP 1jdCz84ApQ0y8LJAAMa2RlxbxwX7lQ+BBeflcWIRfwNKInogH9KQsClbY/dtc6hO I8faIGhR8O2NmJH5k5EvH58M10jd9uKgm7LO25w== 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= 1519642482; bh=wHRy678WchjhM82JyNYTEbAh4EeUyYa5iKBVxiN9fEQ=; b=m hExdp3hQAF1ZT+ASFLC9USX1V2Cwt1qOmsjxfmDSIokMq//7sXhLodrqVj1FJc4d NVHi6r1jgo72T6/73RkHTvQu1Pt+VPxn0Gu2Gfz0hI63obUGOxJmrg7hCb+VSh/I rzHW1FWl8PnlTvDqdfBq1zXB2c+vm2AtBwg+n0cyWUdP3dzMQ0IZ5jjt018XtgPQ tH5/oF0Dg2lmAoJaszkMnOuIBiAGpY1jsGFiq8uSuHY+cy3jVYYkFhhRN8LaIpSg VQtdc5T67JR1NJezR9YONdSuxRG5kGeLx3fiayvoDHi9GJGeYFN4FDqvqGwbH37Y CxjRxK/kcQnCEfr8CI5Iw== ARC-Authentication-Results: i=1; mx6.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: mx6.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 S1752626AbeBZKyl (ORCPT ); Mon, 26 Feb 2018 05:54:41 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:5708 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752353AbeBZKyk (ORCPT ); Mon, 26 Feb 2018 05:54:40 -0500 Subject: Re: [RFC PATCH 2/2] serial: 8250_dw: support polling mode To: Andy Shevchenko , , , , , , References: <1519324923-196857-1-git-send-email-john.garry@huawei.com> <1519324923-196857-3-git-send-email-john.garry@huawei.com> <1519407313.10722.127.camel@linux.intel.com> CC: , , From: John Garry Message-ID: Date: Mon, 26 Feb 2018 10:54:06 +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: <1519407313.10722.127.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 17:35, Andy Shevchenko wrote: > On Fri, 2018-02-23 at 02:42 +0800, John Garry wrote: >> It would be useful to make this driver support some >> 8250-compatible devices which have no interrupt line. >> >> For these, we allow for no interrupt, and will fallback on >> polling mode. >> >> Note: the 8250 dt bindings state that "interrupts" >> is a required property: >> "interrupts : should contain uart interrupt." >> >> But the 8250_of.c driver can live without it. So >> this patch is going this way also. > > It should be documented in the binding. Agreed. I find the wording a bit ambigious in bindings/serial/8250.txt and snps-dw-apb-uart.txt: Required properties: [...] - interrupts : should contain uart interrupt. It uses the word "should", and not "must". Maybe "should" means "must"... > >> if (irq < 0) { >> - if (irq != -EPROBE_DEFER) >> - dev_err(dev, "cannot get irq\n"); >> - return irq; >> + if (irq == -EPROBE_DEFER) >> + return irq; >> + dev_warn(dev, "cannot get irq, using polling >> mode\n"); >> + irq = 0; > > NO_IRQ _is_ 0. You need to do something like > > if (irq < 0) } > ... leave existing code ... > } > > if (!irq) > dev_warn(, "Use polling mode\n"); OK > Thanks, John