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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 1F61AC38A30 for ; Sun, 19 Apr 2020 16:47:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8425214D8 for ; Sun, 19 Apr 2020 16:47:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=walle.cc header.i=@walle.cc header.b="sZYcqRFc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726743AbgDSQrd (ORCPT ); Sun, 19 Apr 2020 12:47:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725793AbgDSQrd (ORCPT ); Sun, 19 Apr 2020 12:47:33 -0400 Received: from ssl.serverraum.org (ssl.serverraum.org [IPv6:2a01:4f8:151:8464::1:2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 101CAC061A0C; Sun, 19 Apr 2020 09:47:33 -0700 (PDT) Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id CD1D023059; Sun, 19 Apr 2020 18:47:30 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1587314851; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=X5Lq9CuvSC4Dq2s5AcEVgmb8Ojr37XvEcpZUqSG+/R0=; b=sZYcqRFcZObp1IsyRDDmJUvQPuSWf0VvAnWSUnZaYXFfX+N9rvBiHHoBXk1oSGX8Vrq6HK l2wT3NlWfsu67Mne/ig55oUd4p+qp1iNGGfGzGpIlmb6b65YspXoHwsGmO41sTcQTsLinc 0U6IWmZDlGvyszO/z2UCCcYzONV5Ac4= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Sun, 19 Apr 2020 18:47:30 +0200 From: Michael Walle To: Andrew Lunn Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Jean Delvare , Guenter Roeck , Florian Fainelli , Heiner Kallweit , Russell King , "David S . Miller" Subject: Re: [PATCH net-next 3/3] net: phy: bcm54140: add hwmon support In-Reply-To: <20200419162928.GL836632@lunn.ch> References: <20200417192858.6997-1-michael@walle.cc> <20200417192858.6997-3-michael@walle.cc> <20200417195003.GG785713@lunn.ch> <35d00dfe1ad24b580dc247d882aa2e39@walle.cc> <20200417201338.GI785713@lunn.ch> <84679226df03bdd8060cb95761724d3a@walle.cc> <20200417212829.GJ785713@lunn.ch> <4f3ff33f78472f547212f87f75a37b66@walle.cc> <20200419162928.GL836632@lunn.ch> Message-ID: X-Sender: michael@walle.cc User-Agent: Roundcube Webmail/1.3.10 X-Spamd-Bar: + X-Rspamd-Server: web X-Rspamd-Queue-Id: CD1D023059 X-Spamd-Result: default: False [1.40 / 15.00]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TAGGED_RCPT(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DKIM_SIGNED(0.00)[]; RCPT_COUNT_SEVEN(0.00)[10]; NEURAL_HAM(-0.00)[-0.970]; RCVD_COUNT_ZERO(0.00)[0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_CC(0.00)[vger.kernel.org,suse.com,roeck-us.net,gmail.com,armlinux.org.uk,davemloft.net]; MID_RHS_MATCH_FROM(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 2020-04-19 18:29, schrieb Andrew Lunn: > On Sun, Apr 19, 2020 at 12:29:23PM +0200, Michael Walle wrote: >> Am 2020-04-17 23:28, schrieb Andrew Lunn: >> > On Fri, Apr 17, 2020 at 11:08:56PM +0200, Michael Walle wrote: >> > > Am 2020-04-17 22:13, schrieb Andrew Lunn: >> > > > > Correct, and this function was actually stolen from there ;) This was >> > > > > actually stolen from the mscc PHY ;) >> > > > >> > > > Which in itself indicates it is time to make it a helper :-) >> > > >> > > Sure, do you have any suggestions? >> > >> > mdiobus_get_phy() does the bit i was complaining about, the mdiobus >> > internal knowledge. >> >> But that doesn't address your other comment. > > Yes, you are right. But i don't think you can easily generalize the > rest. It needs knowledge of the driver private structure to reference > pkg_init. You would have to move that into phy_device. > >> >> > There is also the question of locking. What happens if the PHY devices >> > is unbound while you have an instance of its phydev? >> >> Is there any lock one could take to avoid that? > > phy_attach_direct() does a get_device(). That at least means the > struct device will not go away. I don't know the code well enough to > know if that will also stop the phy_device structure from being freed. > We might need mdiobus_get_phy() to also do a get_device(), and add a > mdiobus_put_phy() which does a put_device(). > >> > What happens if the base PHY is unbound? Are the three others then >> > unusable? >> >> In my case, this would mean the hwmon device is also removed. I don't >> see any other way to do it right now. I guess it would be better to >> have the hwmon device registered to some kind of parent device. > > The phydev structure might go away. But the hardware is still > there. You can access it via address on the bus. What you have to be > careful of is using the phydev for a different phy. But the hwmon is registered to the device of the PHY which might be unbound. So it will also be removed, correct? FWIW I don't think that is likely to happen in my case ;) > >> For the BCM54140 there are three different functions: >> (1) PHY functions accessible by the PHYs own address (ie PHY >> status/control) >> (2) PHY functions but only accessible by the global registers (ie >> interrupt enables per PHY of the shared interrupt pin) >> (3) global functions (like sensors, global configuration) >> >> (1) is already supported in the current PHY framework. (2) and (3) >> need the "hack" which uses mdiobus_read/write() with the base >> address. > > Is the _is_pkg_init() function the only place you need to access some > other phy_device structure. yes. > Maybe we need a phydev->shared structure, which all PHYs in one > package share? That came to my mind too. But how could the PHY core find out which shared structure belongs to which phydev? I guess the phydev have to find out, but then how does it tell the PHY core that it wants such a shared structure. Have the (base) PHY address as an identifier? > Get the core to do reference counting on the structure? > Add helpers phy_read_shared(), phy_write_shared(), etc, which does > MDIO accesses on the base device, taking care of the locking. The "base" access is another thing, I guess, which has nothing to do with the shared structure. Also I presume not every PHY has the base address as some global register access. Eg. this PHY also have "base + 4" (or depending on the configuration base + 3, that is the last PHY of the four) as a special register access. > pkg_init > is a member of this shared structure. And have a void * priv in shared > for shared driver private data? if you have a void *priv, why would you need pkg_init, which is an implementation detail of the phydev. I guess it is enough to just have a void *shared (I don't know about the locking for now). -michael