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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 62167C10DCE for ; Thu, 12 Mar 2020 10:58:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45DE720716 for ; Thu, 12 Mar 2020 10:58:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726725AbgCLK6r (ORCPT ); Thu, 12 Mar 2020 06:58:47 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2553 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726302AbgCLK6q (ORCPT ); Thu, 12 Mar 2020 06:58:46 -0400 Received: from lhreml701-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 12875E41F06CB2DA1C75; Thu, 12 Mar 2020 10:58:43 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by lhreml701-cah.china.huawei.com (10.201.108.42) with Microsoft SMTP Server (TLS) id 14.3.408.0; Thu, 12 Mar 2020 10:58:42 +0000 Received: from [127.0.0.1] (10.202.226.45) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Thu, 12 Mar 2020 10:58:42 +0000 Subject: Re: [PATCH V2 05/13] pm80xx : Support for char device. To: Jinpu Wang , Doug Gilbert , Deepak Ukey CC: "Martin K. Petersen" , "James E.J. Bottomley" , Linux SCSI Mailinglist , , Viswas G , Jack Wang , , Vikram Auradkar , , , Radha Ramachandran , References: <20200117071923.7445-1-deepak.ukey@microchip.com> <20200117071923.7445-6-deepak.ukey@microchip.com> <68e52d06-1fd2-770d-627a-7e8c79067282@huawei.com> <3e76b6e1-9c3d-2e5c-896e-f1af9a785fe5@huawei.com> <92a5ed32-eecb-dc1b-c485-1b691573f5de@interlog.com> From: John Garry Message-ID: <647fdd73-d4f5-efc3-a496-e161aa48f70a@huawei.com> Date: Thu, 12 Mar 2020 10:58:41 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.45] X-ClientProxiedBy: lhreml722-chm.china.huawei.com (10.201.108.73) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 12/03/2020 08:49, Jinpu Wang wrote: > On Wed, Mar 11, 2020 at 11:13 PM Douglas Gilbert wrote: >> >> On 2020-03-11 1:08 p.m., Jinpu Wang wrote: >>> On Tue, Jan 28, 2020 at 10:43 AM wrote: >>>> >>>> >>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >>>> >>>> On 22/01/2020 08:50, Deepak.Ukey@microchip.com wrote: >>>>> -r--r--r-- 1 root root 4096 Jan 21 12:05 running_disparity_error_count >>>>> *** >>>>> -r--r--r-- 1 root root 4096 Jan 21 12:05 sas_address >>>>> lrwxrwxrwx 1 root root 0 Jan 21 11:45 subsystem -> >>>>> ../../../../../../../class/sas_phy >>>>> -r--r--r-- 1 root root 4096 Jan 21 12:05 target_port_protocols >>>>> -rw-r--r-- 1 root root 4096 Jan 21 11:45 uevent >>>>> >>>>> Maybe the other stuff provided in the patches are useful, I don't know. >>>>> But debugfs seems better for that. >>>>> >>>>> - 0006-pm80xx-sysfs-attribute-for-number-of-phys >>>>> - 0007-pm80xx-IOCTL-functionality-to-get-phy-status gets things like Programmed Link Rate, Negotiated Link Rate, PHY Identifier >>>>> - 0008-pm80xx-IOCTL-functionality-to-get-phy-error provides other things like Invalid Dword Error Count, Disparity Error Count >>>>> - Thanks for addressing it. We can get this info from /sys/class/sas_phy and /sys/class/sas_port so we will drop these above mentioned three patches from the next - patch series. >>>>> >>> >>>>> >>>>> - 0009-pm80xx-IOCTL-functionality-for-GPIO >>>>> - 0013-pm80xx-IOCTL-functionality-for-TWI-device >>>>> - For the above patches management utility passes command specific information to driver through IOCTL structure, which used by driver to frame the command and - send to FW. We are using the IOCTL interface for the same. Please let us know your thought. >>>> >>>> So I specifically questioned the SGPIO patch and why it would have an IOCTL, as this function is supported in kernel libsas/SAS transport code as an SMP function. >>>>> Thank you for your suggestions. We will make use of function supported in libsas. >>> >>> So basically you only need IOCTL for GPIO and TWI devices, others can >>> implement via libsas interface or from sysfs directly. >>> >>> I would like to suggest you do send out other changes without the >>> IOCTL parts first, and consider again Is it really needed by the user >>> to control GPIO and TWI, and if there is other way to do it? >>> >>> Sorry, I don't have a better suggestion! >> >> LSI SAS HBAs (LSI now owned by Broadcom) implement an internal ** SMP >> target. It can be seen here: >> >> # ls /dev/bsg >> 3:0:0:0 3:0:3:0 8:0:0:0 8:0:0:3 end_device-3:1 expander-3:0 >> 3:0:1:0 4:0:0:0 8:0:0:1 8:0:0:4 end_device-3:1:0 expander-3:1 >> 3:0:2:0 7:0:0:0 8:0:0:2 end_device-3:0:1 end_device-3:2 sas_host3 >> >> It is the last device node: "sas_host3". How do I know it is a SMP target? >> Because this works: >> >> # smp_read_gpio /dev/bsg/sas_host3 >> Read GPIO register response: >> GPIO_CFG[0]: >> version: 0 >> GPIO enable: 1 >> cfg register count: 2 >> gp register count: 1 >> supported drive count: 16 >> JFYI, that specific command is not implemented for libsas SMP host handler (see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/scsi/libsas/sas_host_smp.c?h=v5.6-rc5#n278), but the write command should be ok >> When you work out what LSI are doing with this, perhaps you could write >> an article about it and make it publicly available. Firmware magic... >> It is always a good idea to see how your competitors solve problems :-) > This sounds indeed a better solution, thanks for the info, Doug > > @Deepak Ukey can you check if you guys can also do it this way? > > Regards, > Jack Wang > . >