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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 6BA3BC32767 for ; Mon, 6 Jan 2020 05:42:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3E89421775 for ; Mon, 6 Jan 2020 05:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578289354; bh=3RhNzBGs+D8rTsIRLrcYDaHymOOyLXkNlDfsc8JeyZY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Ud+5ejJWq08SWYbye85ikNmP/tyKUGjMxzW3Ly7VctoCt+Fy0N6JG8pcbnsLCeyHj UUTSKEjvXFRSrp7c8JlPl21dzWVCPcBqixBZVp8rLLfnDOAIjsDotPOv5OQdrp26J0 RxWmwzNRhX52pSP0EWidliFI9trGbp8vYusHKDqE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726760AbgAFFm0 (ORCPT ); Mon, 6 Jan 2020 00:42:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:38518 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbgAFFmZ (ORCPT ); Mon, 6 Jan 2020 00:42:25 -0500 Received: from localhost (unknown [117.99.94.5]) (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 16C1121734; Mon, 6 Jan 2020 05:42:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578289345; bh=3RhNzBGs+D8rTsIRLrcYDaHymOOyLXkNlDfsc8JeyZY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MinmSbcCkzk1oiZEJyhRn/jaFO5NQ/wKcCKKfRm5rrLa7GBYYqS9ZqTNBrXcPIW94 vBzhi30/Faml22jv2YFmujSrhy3fH15V+28W/X8yn6AR5Y8i4QcVdVik9MvJ4CD6zo ZvjRndP7VTCN1eHYPOGKz2/oTI/s7L/UjbaGFm28= Date: Mon, 6 Jan 2020 11:12:21 +0530 From: Vinod Koul To: Pierre-Louis Bossart Cc: alsa-devel@alsa-project.org, tiwai@suse.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Ranjani Sridharan , broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, slawomir.blauciak@intel.com, Sanyog Kale , Bard liao , Rander Wang Subject: Re: [alsa-devel] [PATCH v5 09/17] soundwire: intel: remove platform devices and use 'Master Devices' instead Message-ID: <20200106054221.GN2818@vkoul-mobl> References: <20191217210314.20410-1-pierre-louis.bossart@linux.intel.com> <20191217210314.20410-10-pierre-louis.bossart@linux.intel.com> <20191227090826.GM3006@vkoul-mobl> <5be4d9df-0f46-d36f-471c-aae9e1f55cc0@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5be4d9df-0f46-d36f-471c-aae9e1f55cc0@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27-12-19, 18:13, Pierre-Louis Bossart wrote: > > > > > +extern struct sdw_md_driver intel_sdw_driver; > > > > who uses this intel_sdw_driver? I would assumed someone would register > > this with the core... > > this is a structure used by intel_init(), see the following code. > > + md = sdw_md_add(&intel_sdw_driver, > + res->parent, > + acpi_fwnode_handle(adev), > + i); > > that will in turn call intel_master_probe() as defined below: > > +struct sdw_md_driver intel_sdw_driver = { > + .probe = intel_master_probe, > + .startup = intel_master_startup, > + > > > > - link->pdev = pdev; > > > - link++; > > > + /* let the SoundWire master driver to its probe */ > > > + md->driver->probe(md, link); > > > > So you are invoking driver probe here.. That is typically role of driver > > core to do that.. If we need that, make driver core do that for you! > > > > That reminds me I am missing match code for master driver... > > There is no match for the master because it doesn't have an existence in > ACPI. There are no _ADR or HID that can be used, the only thing that exists > is the Controller which has 4 sublinks. Each master must be added by hand. > > Also the SoundWire master cannot be enumerated or matched against a > SoundWire bus, since it controls the bus itself (that would be a chicken and > egg problem). The SoundWire master would need to be matched on a parent bus > (which does not exist for Intel) since the hardware is embedded in a larger > audio cluster that's visible on PCI only. > > Currently for Intel platforms, the SoundWire master device is created by the > SOF driver (via the abstraction in intel_init.c). That is okay for me, the thing that is bit confusing is having a probe etc and no match.. (more below).. > > So we seem to be somewhere is middle wrt driver probing here! IIUC this > > is not a full master driver, thats okay, but then it is not > > completely transparent either... > > > > I was somehow thinking that the driver will continue to be > > 'platform/acpi/of' driver and master device abstraction will be > > handled in the core (for example see how the busses like i2c handle > > this). The master device is created and used to represent but driver > > probing etc is not done > > I2C controllers are typically PCI devices or have some sort of ACPI > description. This is not the case for SoundWire masters on Intel platforms, Well the world is not PCI/ACPI... We have controllers which are DT described and work in same manner as a PCI device. > so even if I wanted to I would have no ability to implement any matching or > parent bus registration. > > Also the notion of 'probe' does not necessarily mean that the device is > attached to a bus, we use DAI 'drivers' in ASoC and still have probe/remove > callbacks. The "big" difference is that probe is called by core (asoc) and not by driver onto themselves.. IMO that needs to go away. > And if you look at the definitions, we added additional callbacks since > probe/remove are not enough to deal with hardware restrictions: > > For Intel platforms, we have a startup() callback which is only invoked once > the DSP is powered and the rails stable. Likewise we added an > 'autonomous_clock_stop()' callback which will be needed when the Linux > driver hands-over control of the hardware to the DSP firmware, e.g. to deal > with in-band wakes in D0i3. > > FWIW, the implementation here follows what was suggested for Greybus 'Host > Devices' [1] [2], so it's not like I am creating any sort of dangerous > precedent. > > [1] > https://elixir.bootlin.com/linux/latest/source/drivers/greybus/es2.c#L1275 > [2] https://elixir.bootlin.com/linux/latest/source/drivers/greybus/hd.c#L124 And if you look closely all this work is done by core not by drivers! Drivers _should_ never do all this, it is the job of core to do that for you. -- ~Vinod