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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1149BE7AD7D for ; Tue, 3 Oct 2023 16:55:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240526AbjJCQz0 (ORCPT ); Tue, 3 Oct 2023 12:55:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231388AbjJCQzW (ORCPT ); Tue, 3 Oct 2023 12:55:22 -0400 Received: from mx01.omp.ru (mx01.omp.ru [90.154.21.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1EBE8B7; Tue, 3 Oct 2023 09:55:18 -0700 (PDT) Received: from [192.168.1.103] (178.176.78.48) by msexch01.omp.ru (10.188.4.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.986.14; Tue, 3 Oct 2023 19:55:08 +0300 Subject: Re: [PATCH 3/4] pata_parport: add custom version of wait_after_reset To: Damien Le Moal , Ondrej Zary , Sudip Mukherjee CC: Christoph Hellwig , Tim Waugh , , , References: <20230930191511.24994-1-linux@zary.sk> <20230930191511.24994-4-linux@zary.sk> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <14129ea5-1597-efce-e782-23a95f3c0bd9@omp.ru> Date: Tue, 3 Oct 2023 19:55:07 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [178.176.78.48] X-ClientProxiedBy: msexch01.omp.ru (10.188.4.12) To msexch01.omp.ru (10.188.4.12) X-KSE-ServerInfo: msexch01.omp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.59, Database issued on: 10/03/2023 16:33:34 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 59 X-KSE-AntiSpam-Info: Lua profiles 180330 [Oct 03 2023] X-KSE-AntiSpam-Info: Version: 5.9.59.0 X-KSE-AntiSpam-Info: Envelope from: s.shtylyov@omp.ru X-KSE-AntiSpam-Info: LuaCore: 535 535 da804c0ea8918f802fc60e7a20ba49783d957ba2 X-KSE-AntiSpam-Info: {rep_avail} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: {relay has no DNS name} X-KSE-AntiSpam-Info: {SMTP from is not routable} X-KSE-AntiSpam-Info: 127.0.0.199:7.1.2;omp.ru:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1;178.176.78.48:7.1.2 X-KSE-AntiSpam-Info: FromAlignment: s X-KSE-AntiSpam-Info: {rdns complete} X-KSE-AntiSpam-Info: {fromrtbl complete} X-KSE-AntiSpam-Info: ApMailHostAddress: 178.176.78.48 X-KSE-AntiSpam-Info: Rate: 59 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dmarc=none header.from=omp.ru;spf=none smtp.mailfrom=omp.ru;dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 10/03/2023 16:37:00 X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 10/3/2023 12:09:00 PM X-KSE-Attachment-Filter-Triggered-Rules: Clean X-KSE-Attachment-Filter-Triggered-Filters: Clean X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/3/23 3:55 AM, Damien Le Moal wrote: [...] >> Some parallel adapters (e.g. EXP Computer MC-1285B EPP Cable) return >> bogus values when there's no master device present. This can cause >> reset to fail, preventing the lone slave device (such as EXP Computer >> CD-865) from working. >> >> Add custom version of wait_after_reset that ignores master failure when >> a slave device is present. The custom version is also needed because >> the generic ata_sff_wait_after_reset uses direct port I/O for slave >> device detection. >> >> Signed-off-by: Ondrej Zary >> --- >> drivers/ata/pata_parport/pata_parport.c | 65 ++++++++++++++++++++++++- >> 1 file changed, 64 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/ata/pata_parport/pata_parport.c b/drivers/ata/pata_parport/pata_parport.c >> index cf87bbb52f1f..b3db953e615a 100644 >> --- a/drivers/ata/pata_parport/pata_parport.c >> +++ b/drivers/ata/pata_parport/pata_parport.c >> @@ -80,6 +80,69 @@ static bool pata_parport_devchk(struct ata_port *ap, unsigned int device) >> return (nsect == 0x55) && (lbal == 0xaa); >> } >> >> +static int pata_parport_wait_after_reset(struct ata_link *link, >> + unsigned int devmask, >> + unsigned long deadline) >> +{ >> + struct ata_port *ap = link->ap; >> + struct pi_adapter *pi = ap->host->private_data; >> + unsigned int dev0 = devmask & (1 << 0); >> + unsigned int dev1 = devmask & (1 << 1); >> + int rc, ret = 0; >> + >> + ata_msleep(ap, ATA_WAIT_AFTER_RESET); >> + >> + /* always check readiness of the master device */ >> + rc = ata_sff_wait_ready(link, deadline); >> + /* some adapters return bogus values if master device is not present, >> + * so don't abort now if a slave device is present >> + */ > > In addition to Sergey's comment, please move this comment inside the "if", or > even better, merge it with the otherwise not very useful "always check > readiness..." comment. That comment was copied from ata_sff_wait_after_reset(), I think... [...] >> + /* if device 1 was found in ata_devchk, wait for register >> + * access briefly, then wait for BSY to clear. >> + */ >> + if (dev1) { >> + int i; >> + >> + pata_parport_dev_select(ap, 1); >> + >> + /* Wait for register access. Some ATAPI devices fail >> + * to set nsect/lbal after reset, so don't waste too >> + * much time on it. We're gonna wait for !BSY anyway. >> + */ >> + for (i = 0; i < 2; i++) { >> + u8 nsect, lbal; >> + >> + nsect = pi->proto->read_regr(pi, 0, ATA_REG_NSECT); >> + lbal = pi->proto->read_regr(pi, 0, ATA_REG_LBAL); >> + if ((nsect == 1) && (lbal == 1)) >> + break; >> + ata_msleep(ap, 50); /* give drive a breather */ > > Please move the comment on its own line above the sleep call. Again, copied verbatim from ata_sff_wait_after_reset()... >> + } >> + >> + rc = ata_sff_wait_ready(link, deadline); >> + if (rc) { >> + if (rc != -ENODEV) >> + return rc; >> + ret = rc; >> + } >> + } >> + >> + /* is all this really necessary? */ > > I don't know. It is your driver... So either drop this comment, or clearly > explain why this is done. And again, copied verbatim from ata_sff_wait_after_reset()... >> + pata_parport_dev_select(ap, 0); >> + if (dev1) >> + pata_parport_dev_select(ap, 1); >> + if (dev0) >> + pata_parport_dev_select(ap, 0); > > Can you have dev1 && dev0 == true ? This seems like the second if should be an > "else if", but it is not clear what this is doing. I guess this tries to leave the valid taskfile regs readable on a channel, instead of just 0xff... [...] MBR, Sergey