From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH v13 0/6] flexcan: Add support for powerpc flexcan (freescale p1010) Date: Tue, 25 Oct 2011 16:37:16 -0500 Message-ID: <4EA72C0C.3000908@freescale.com> References: <1313551944-28603-1-git-send-email-holt@sgi.com> <16FBAA47-5133-43A1-80CE-C6D63B79FB5D@kernel.crashing.org> <20111018094328.GC22814@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: Robin Holt , , U Bhaskar-B22300 , , PPC list , "David S. Miller" To: Kumar Gala Return-path: Received: from ch1ehsobe001.messaging.microsoft.com ([216.32.181.181]:40995 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753370Ab1JYVhX (ORCPT ); Tue, 25 Oct 2011 17:37:23 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 10/18/2011 06:43 AM, Kumar Gala wrote: > >>> Robin, >>> >>> Do you remember why we went with just 'fsl,p1010-flexcan' as the device tree compatible? Do we feel the flex can on P1010 isn't the same as on MPC5xxx? or the ARM SoCs? >> >> The decision was due to the fact there is no true "generic" fsl.flexcan >> chip free of any SOC implementation and therefore not something which >> could be separately defined. That decision was made by Grant Likely. >> I will inline that email below. >> >> Robin > > > Thanks, I'll look into this internally at FSL. I think its confusing as hell to have "fsl,p1010-flexcan" in an ARM .dts It's confusing to have devices labelled in vague ways that we can't tie back to any real piece of hardware, or even a public architectural spec. If you're talking to our hardware people, ask them to put public names and versions, guaranteed unique throughout FSL, on all of our logic blocks -- with public block manuals that have any SW-relevant integration parameters clearly itemized. Why is putting "fsl,p1010-flexcan" an an ARM device any more confusing than putting it on some PowerPC chip that is not a p1010? Think of it like a PCI ID, the actual value not being meaningful for much other than its uniqueness and the ability to find a manual for the hardware. This has been the recommended practice for quite some time. > and don't think any reasonable ARM customer of FSL would know to put > a PPC SOC name in their .dts. If an ARM device tree comes along that just has "fsl,some-arm-chip-flexcan", so what? Let the same driver bind against both, again like PCI IDs. Additional compatibles are mainly a convenience to give things a chance to work before the driver is updated (a frequent irritant with PCI IDs and new hardware). Ideally we would be publishing a sample device tree for our ARM chips and their peripherals, though. :-P > I'll ask the HW guys what's going on > so we can come up with a bit more generic name so we don't have to > constantly change this. Even if its just: > > fsl,ppc-flexcan & fsl,arm-flexcan. Why is CPU instruction set relevant? Would a QorIQ customer think to check for an existing compatible in mpc5xxx, or even mpc83xx or mpc86xx? -Scott