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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 6C2CBC0044D for ; Wed, 11 Mar 2020 22:13:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D265206E7 for ; Wed, 11 Mar 2020 22:13:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729590AbgCKWNP (ORCPT ); Wed, 11 Mar 2020 18:13:15 -0400 Received: from smtp.infotech.no ([82.134.31.41]:43790 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729518AbgCKWNP (ORCPT ); Wed, 11 Mar 2020 18:13:15 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id C839D20424C; Wed, 11 Mar 2020 23:13:12 +0100 (CET) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id LAjpja14CHev; Wed, 11 Mar 2020 23:13:05 +0100 (CET) Received: from [192.168.48.23] (host-23-251-188-50.dyn.295.ca [23.251.188.50]) by smtp.infotech.no (Postfix) with ESMTPA id 60185204153; Wed, 11 Mar 2020 23:13:02 +0100 (CET) Reply-To: dgilbert@interlog.com Subject: Re: [PATCH V2 05/13] pm80xx : Support for char device. To: Jinpu Wang , Deepak Ukey Cc: John Garry , "Martin K. Petersen" , "James E.J. Bottomley" , Linux SCSI Mailinglist , Vasanthalakshmi.Tharmarajan@microchip.com, Viswas G , Jack Wang , yuuzheng@google.com, Vikram Auradkar , vishakhavc@google.com, bjashnani@google.com, Radha Ramachandran , akshatzen@google.com 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> From: Douglas Gilbert Message-ID: <92a5ed32-eecb-dc1b-c485-1b691573f5de@interlog.com> Date: Wed, 11 Mar 2020 18:13:00 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 7bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org 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 When you work out what LSI are doing with this, perhaps you could write an article about it and make it publicly available. It is always a good idea to see how your competitors solve problems :-) Doug Gilbert ** I call it "internal" because it is not seen when doing a SMP DISCOVER on a SAS expander to which that SAS HBA is connected.