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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 84EF3C004C9 for ; Tue, 7 May 2019 05:27:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E56420989 for ; Tue, 7 May 2019 05:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557206861; bh=UVbc4iB6zImLc+u0YFa5xDna8kmTDTd7akBPgEp3Vm4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=mwiLc/p5CXPsMLw3r6XZ/qhY7CTW1UW6YsTlImBkkSs8hAXavKOFvflWEQJZ1ZRtM YjHUH00ano21O5qeLraxAK8ZuE/9E+umGWGDVKles+62jnw6ZbBjWTtdzovG28sv8Y QXSpIuSs+VEufgDlYxkQYo2f3nH4xcfBT5bu8VRc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726449AbfEGF1k (ORCPT ); Tue, 7 May 2019 01:27:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:52404 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725839AbfEGF1j (ORCPT ); Tue, 7 May 2019 01:27:39 -0400 Received: from localhost (unknown [106.200.210.185]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 99391206A3; Tue, 7 May 2019 05:27:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557206858; bh=UVbc4iB6zImLc+u0YFa5xDna8kmTDTd7akBPgEp3Vm4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C/+Tyj3EJnEfQtmPl4wAuOQmnEKvTFlW8qYh1dF6fbWNETkJKsnDW4/hwieXjvtRh e6JxXYLq0TKNmzbFmn/p+2eDhYS30fnWzdO6OAXl9PLL0ps1lSJktKaNZeYrHg1sq4 XDQEjEqG4MpYNu5dAjwWMA0jGzYWSNhwVqhJBhGA= Date: Tue, 7 May 2019 10:57:32 +0530 From: Vinod Koul To: Pierre-Louis Bossart Cc: Greg KH , alsa-devel@alsa-project.org, tiwai@suse.de, linux-kernel@vger.kernel.org, liam.r.girdwood@linux.intel.com, broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, joe@perches.com, Sanyog Kale Subject: Re: [alsa-devel] [RFC PATCH 1/7] soundwire: Add sysfs support for master(s) Message-ID: <20190507052732.GD16052@vkoul-mobl> References: <20190504010030.29233-1-pierre-louis.bossart@linux.intel.com> <20190504010030.29233-2-pierre-louis.bossart@linux.intel.com> <20190504065242.GA9770@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06-05-19, 21:24, Pierre-Louis Bossart wrote: > > > > +int sdw_sysfs_bus_init(struct sdw_bus *bus) > > > +{ > > > + struct sdw_master_sysfs *master; > > > + int err; > > > + > > > + if (bus->sysfs) { > > > + dev_err(bus->dev, "SDW sysfs is already initialized\n"); > > > + return -EIO; > > > + } > > > + > > > + master = kzalloc(sizeof(*master), GFP_KERNEL); > > > + if (!master) > > > + return -ENOMEM; > > > > Why are you creating a whole new device to put all of this under? Is > > this needed? What will the sysfs tree look like when you do this? Why > > can't the "bus" device just get all of these attributes and no second > > device be created? > > I tried a quick hack and indeed we could simplify the code with something as > simple as: > > [attributes omitted] > > static const struct attribute_group sdw_master_node_group = { > .attrs = master_node_attrs, > .name = "mipi-disco" > }; > > int sdw_sysfs_bus_init(struct sdw_bus *bus) > { > return sysfs_create_group(&bus->dev->kobj, &sdw_master_node_group); > } > > void sdw_sysfs_bus_exit(struct sdw_bus *bus) > { > sysfs_remove_group(&bus->dev->kobj, &sdw_master_node_group); > } > > which gives me a simpler structure and doesn't require additional > pretend-devices: > > /sys/bus/acpi/devices/PRP00001:00/int-sdw.0/mipi-disco# ls > clock_gears > /sys/bus/acpi/devices/PRP00001:00/int-sdw.0/mipi-disco# more clock_gears > 8086 > > The issue I have is that for the _show() functions, I don't see a way to go > from the device argument to bus. In the example above I forced the output > but would need a helper. > > static ssize_t clock_gears_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > struct sdw_bus *bus; // this is what I need to find from dev > ssize_t size = 0; > int i; > > return sprintf(buf, "%d \n", 8086); > } > > my brain is starting to fry, but I don't see how container_of() would work > here since the bus structure contains a pointer to the device. I don't also > see a way to check for all devices for the bus_type soundwire. > For the slaves we do have a macro based on container_of(), so wondering if > we made a mistake in the bus definition? Vinod, any thoughts? yeah I dont recall a way to get bus fed into create_group, I did look at the other examples back then and IIRC and most of them were using a global to do the trick (I didn't want to go down that route). I think that was the reason I wrote it this way... BTW if you do use psedo-device you can create your own struct foo which embeds device and then then you can use container approach to get foo (and foo contains bus as a member). Greg, any thoughts? Thanks -- ~Vinod