Return-path: Received: from mail.academy.zt.ua ([82.207.120.245]:18525 "EHLO mail.academy.zt.ua" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755245Ab1DLTZF (ORCPT ); Tue, 12 Apr 2011 15:25:05 -0400 Subject: Re: [RFC][PATCH] axi: add AXI bus driver From: George Kashperko To: =?UTF-8?Q?Rafa=C5=82_Mi=C5=82ecki?= Cc: balbi@ti.com, linux-wireless@vger.kernel.org, "John W. Linville" , b43-dev@lists.infradead.org, Michael =?ISO-8859-1?Q?B=FCsch?= , Larry Finger , Arend van Spriel , linux-arm-kernel@lists.infradead.org, Russell King , Arnd Bergmann , Andy Botting , linuxdriverproject , "linux-kernel@vger.kernel.org" In-Reply-To: References: <1302566227-23788-1-git-send-email-zajec5@gmail.com> <20110412133633.GR15130@legolas.emea.dhcp.ti.com> <1302634039.14216.10.camel@dev.znau.edu.ua> Content-Type: text/plain; charset=UTF-8 Date: Tue, 12 Apr 2011 22:12:29 +0300 Message-Id: <1302635550.14216.21.camel@dev.znau.edu.ua> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: > 2011/4/12 George Kashperko : > > > >> Hi, > >> > >> On Tue, Apr 12, 2011 at 01:57:07AM +0200, Rafał Miłecki wrote: > >> > Cc: Michael Büsch > >> > Cc: Larry Finger > >> > Cc: George Kashperko > >> > Cc: Arend van Spriel > >> > Cc: linux-arm-kernel@lists.infradead.org > >> > Cc: Russell King > >> > Cc: Arnd Bergmann > >> > Cc: Andy Botting > >> > Cc: linuxdriverproject > >> > Cc: linux-kernel@vger.kernel.org > >> > Signed-off-by: Rafał Miłecki > >> > --- > >> > V2: Rename to axi > >> > Use DEFINE_PCI_DEVICE_TABLE in bridge > >> > Make use of pr_fmt and pr_* > >> > Store core class > >> > Rename bridge to not b43 specific > >> > Replace magic 0x1000 with BCMAI_CORE_SIZE > >> > Remove some old "ssb" names and defines > >> > Move BCMAI_ADDR_BASE def > >> > Add drvdata field > >> > V3: Fix reloading (kfree issue) > >> > Add 14e4:0x4331 > >> > Fix non-initialized struct issue > >> > Drop useless inline functions wrappers for pci core drv > >> > Proper pr_* usage > >> > V3.1: Include forgotten changes (pr_* and include related) > >> > Explain why we dare to implement empty release function > >> > >> I'm not sure we need this. If you have an IP Core which talks AXI and > >> you want to put it on a PCI bus, you will have a PCI Bus wrapper around > >> that IP Core, so you should go and let the kernel know about that. See > >> [1] for a core IP which talks AXI and [2] for a PCI bus glue layer. > >> > >> Besides, if you introduce this bus layer, it'll be more difficult for > >> other licensees of the same core to re-use the same driver, since it's > >> now talking a PCI emulated on top of AXI. The same can be achieved with > >> the platform_bus which is more widely used, specially on ARM SoCs. > >> > >> [1] http://gitorious.org/usb/usb/blobs/dwc3/drivers/usb/dwc3/core.c > >> [2] http://gitorious.org/usb/usb/blobs/dwc3/drivers/usb/dwc3/dwc3-haps.c > >> > > > > Already noticed earlier that AXI isnt really good name for > > Broadcom-specific axi bus customization. As of tech docs available from > > arm, corelink AXI cores use own identification registers which feature > > different format and layout comparing to that we use for Broadcom cores. > > > > Maybe there is something "standartized" by the DMP specs? If so I'm > > curious if that DMP is obligatory for every axi bus ? > > > > Naming particular Broadcom's implementation just axi limits other > > licensees in reusing axi bus name/code or will require hacks/workarounds > > from them to fit Broadcom-like core scanning/identificating techniques. > > You use bus named AXI to group and manage Broadcom cores, while never > > even publish device records for native axi cores Broadcom use to talk to > > the interconnect through. Yet again, something like bcmb/bcmai looks > > like better name for this bus. > > I don't know, I'm really tired of this. Earlier I was told to not use > anything like bcmai, because it is not Broadcom specific. Now it seems > (and I'm afraid I agree) there is quite a lot of Broadcom specific > stuff. Well, _if_ that "magic" EROM core layout is arm's "standard" for axi ports identification _and_ _if_ that EROM core is obligatory axi component then sure axi name is good one as soon as you consider registering master port (agent) cores with device subsystem as well. I have no clue here about how resolve those _if_'s, hopefully Broadcom guys can enlighten us on the subject. > > > > Also can't figure out how is this implementation supposed to manage > > multicore devices. > > We have got ideas, but let's first find (wait for) such a device ;) bcm4716 usb host ? Don't really know if there are any other multicores. > > > > Any plans on embeddables' support ? > > Sure, if noone will come before me, I'll try to provide support for > embedded devices. However basic support for PCI host in higher on my > priority list. First I want to know it is working at all ;) > Have nice day, George