From owner-freebsd-arm@freebsd.org Wed Aug 19 10:15:57 2020 Return-Path: Delivered-To: freebsd-arm@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id DD4E43B97F9 for ; Wed, 19 Aug 2020 10:15:57 +0000 (UTC) (envelope-from mishin@mh.net.ru) Received: from frog.mh.net.ru (mh.balakovo.san.ru [88.147.158.22]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4BWkFR5XcWz4XVB for ; Wed, 19 Aug 2020 10:15:54 +0000 (UTC) (envelope-from mishin@mh.net.ru) Received: from webmail.mh.net.ru (mouse.home [192.168.5.6]) by frog.mh.net.ru (Postfix) with ESMTPSA id A71A3ABFC9; Wed, 19 Aug 2020 14:15:51 +0400 (+04) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Wed, 19 Aug 2020 14:15:51 +0400 From: Alexander Mishin To: Oleksandr Tymoshenko Subject: Re: Kmod driver at iicbus. attach() and config_intrhook(9) In-Reply-To: <20200819072409.GA59949@bluezbox.com> References: <7fabb65d99aaa74775c1daa91bffb873@mh.net.ru> <3249fa7e-554a-83ef-57b2-7c38aa0b4591@FreeBSD.org> <20200819072409.GA59949@bluezbox.com> User-Agent: Roundcube Webmail/1.4.2 Message-ID: X-Sender: mishin@mh.net.ru X-Rspamd-Queue-Id: 4BWkFR5XcWz4XVB X-Spamd-Bar: +++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=mh.net.ru (policy=none); spf=fail (mx1.freebsd.org: domain of mishin@mh.net.ru does not designate 88.147.158.22 as permitted sender) smtp.mailfrom=mishin@mh.net.ru X-Spamd-Result: default: False [3.48 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_FAIL(1.00)[-all]; FORGED_RECIPIENTS(2.00)[gonzo@bluezbox.com,freebsd-arm@freebsd.org]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; DMARC_POLICY_SOFTFAIL(0.10)[mh.net.ru : No valid SPF, No valid DKIM,none]; ARC_NA(0.00)[]; NEURAL_SPAM_SHORT(0.48)[0.482]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_ONE(0.00)[1]; TO_DN_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:12389, ipnet:88.147.128.0/17, country:RU]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[freebsd-arm]; RCVD_COUNT_TWO(0.00)[2] X-Mailman-Approved-At: Wed, 19 Aug 2020 13:46:57 +0000 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Aug 2020 10:15:57 -0000 Thanks for your answers, especially for "...controllers use interrupts to get notified about...". It helped to understand. Yes, I need it as I check on attach() if the device connected. Everything was fine while I was loading the driver into an already running system, but as soon as I loaded the driver at boot time, I saw that its sysctl variables was only half filled (no result nor calculated values). config_intrhook_oneshot() solved this issue. Thanks once more Oleksandr Tymoshenko писал 2020-08-19 11:24: > Andriy Gapon (avg@FreeBSD.org) wrote: >> On 18/08/2020 22:05, Alexander Mishin wrote: >> > Hi >> > .... >> > But I see that some other devices (from /usr/src/sys/dev) uses CONFIG_INTRHOOK(9) >> > on attach() for initialize themselfs. >> > I wonder if I need this too?... >> >> This is usually needed when a driver needs to talk to its device while >> attaching. E.g., to set some initial configuration or to confirm >> device's >> identity, etc. > > To extend Andriy's explanation a bit: all these operations may perform > I2C transfers and most I2C controllers use interrupts to get notified > about tranfer status change (finished, error, etc...). There is no > guarantee that when driver's attach method is called interrupts are > globally enabled. What would happen in this case is: I2C controller > is going to initiate I2C operation and wait for an interrupt that's > never going to be delivered. CONFIG_INTRHOOK is a solution for this > problem, if your attach method requires interrupts - just split it > in two parts and postpone running interrupt-dependent part until after > interrupts are globally enabled.