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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j57tr-0004C0-6o; Fri, 21 Feb 2020 12:59:23 +0000 Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j57to-0004B7-Ku for linux-i3c@lists.infradead.org; Fri, 21 Feb 2020 12:59:22 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 726AC29617A; Fri, 21 Feb 2020 12:59:14 +0000 (GMT) Date: Fri, 21 Feb 2020 13:59:11 +0100 From: Boris Brezillon To: Greg KH Subject: Re: [PATCH v3 3/5] i3c: master: add i3c_for_each_dev helper Message-ID: <20200221135911.1300170b@collabora.com> In-Reply-To: <20200221115229.GA116368@kroah.com> References: <868e5b37fd817b65e6953ed7279f5063e5fc06c5.1582069402.git.vitor.soares@synopsys.com> <20200219073548.GA2728338@kroah.com> <20200221115229.GA116368@kroah.com> Organization: Collabora X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200221_045920_819913_9C613AE6 X-CRM114-Status: GOOD ( 21.82 ) X-BeenThere: linux-i3c@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux I3C List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jose Abreu , Joao Pinto , "arnd@arndb.de" , "corbet@lwn.net" , "wsa@the-dreams.de" , "linux-kernel@vger.kernel.org" , Vitor Soares , "broonie@kernel.org" , "linux-i3c@lists.infradead.org" , "bbrezillon@kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-i3c" Errors-To: linux-i3c-bounces+linux-i3c=archiver.kernel.org@lists.infradead.org On Fri, 21 Feb 2020 12:52:29 +0100 Greg KH wrote: > On Fri, Feb 21, 2020 at 11:47:22AM +0000, Vitor Soares wrote: > > Hi Greg, > > > > From: Greg KH > > Date: Wed, Feb 19, 2020 at 07:35:48 > > > > > On Wed, Feb 19, 2020 at 01:20:41AM +0100, Vitor Soares wrote: > > > > Introduce i3c_for_each_dev(), an i3c device iterator for use by i3cdev. > > > > > > > > Signed-off-by: Vitor Soares > > > > --- > > > > drivers/i3c/internals.h | 1 + > > > > drivers/i3c/master.c | 12 ++++++++++++ > > > > 2 files changed, 13 insertions(+) > > > > > > > > diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h > > > > index bc062e8..a6deedf 100644 > > > > --- a/drivers/i3c/internals.h > > > > +++ b/drivers/i3c/internals.h > > > > @@ -24,4 +24,5 @@ int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev); > > > > int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev, > > > > const struct i3c_ibi_setup *req); > > > > void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev); > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)); > > > > #endif /* I3C_INTERNAL_H */ > > > > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c > > > > index 21c4372..8e22da2 100644 > > > > --- a/drivers/i3c/master.c > > > > +++ b/drivers/i3c/master.c > > > > @@ -2640,6 +2640,18 @@ void i3c_dev_free_ibi_locked(struct i3c_dev_desc *dev) > > > > dev->ibi = NULL; > > > > } > > > > > > > > +int i3c_for_each_dev(void *data, int (*fn)(struct device *, void *)) > > > > +{ > > > > + int res; > > > > + > > > > + mutex_lock(&i3c_core_lock); > > > > + res = bus_for_each_dev(&i3c_bus_type, NULL, data, fn); > > > > + mutex_unlock(&i3c_core_lock); > > > > > > Ick, why the lock? Are you _sure_ you need that? The core should > > > handle any list locking issues here, right? > > > > I want to make sure that no new devices (eg: Hot-Join capable device) are > > added during this iteration and after this call, each new device will > > release a bus notification. > > > > > > > > I don't see bus-specific-locks around other subsystem functions that do > > > this (like usb_for_each_dev). > > > > I based in I2C use case. > > Check to see if this is really needed, for some reason I doubt it... Can we please try the spidev approach before fixing those problems. None of that would be needed if we declare the i3cdev driver as a regular i3c_device_driver and let user space bind devices it wants to expose through the sysfs interface. As I said earlier, we even have all the pieces we need to automate that using a udev rule, and the resulting patchset would be 'less invasive'/simpler for pretty much the same result. _______________________________________________ linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c