Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:33794 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754098Ab0HKWPc convert rfc822-to-8bit (ORCPT ); Wed, 11 Aug 2010 18:15:32 -0400 MIME-Version: 1.0 In-Reply-To: <20100811212513.GC827@n2100.arm.linux.org.uk> References: <1281550913-17633-1-git-send-email-ohad@wizery.com> <1281550913-17633-4-git-send-email-ohad@wizery.com> <5A47E75E594F054BAF48C5E4FC4B92AB0324110ABD@dbde02.ent.ti.com> <20100811184742.GA21778@nokia.com> <5A47E75E594F054BAF48C5E4FC4B92AB0324110AC1@dbde02.ent.ti.com> <20100811185724.GD21778@nokia.com> <5A47E75E594F054BAF48C5E4FC4B92AB0324110AC7@dbde02.ent.ti.com> <20100811212513.GC827@n2100.arm.linux.org.uk> From: Ohad Ben-Cohen Date: Thu, 12 Aug 2010 01:15:12 +0300 Message-ID: Subject: Re: [PATCH v4 3/8] wireless: wl1271: add platform driver to get board data To: Russell King - ARM Linux Cc: "DebBarma, Tarun Kanti" , "felipe.balbi@nokia.com" , Kalle Valo , "Pandita, Vikram" , "akpm@linux-foundation.org" , "Quadros Roger (Nokia-MS/Helsinki)" , Tony Lindgren , "linux-wireless@vger.kernel.org" , Mark Brown , "linux-mmc@vger.kernel.org" , Nicolas Pitre , San Mehat , "Chikkature Rajashekar, Madhusudhan" , "Coelho Luciano (Nokia-MS/Helsinki)" , "linux-omap@vger.kernel.org" , Ido Yariv , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Aug 12, 2010 at 12:25 AM, Russell King - ARM Linux wrote: > On Thu, Aug 12, 2010 at 12:57:18AM +0530, DebBarma, Tarun Kanti wrote: >> >> > -----Original Message----- >> > From: Felipe Balbi [mailto:felipe.balbi@nokia.com] >> > Sent: Thursday, August 12, 2010 12:27 AM >> > To: DebBarma, Tarun Kanti >> > Cc: Balbi Felipe (Nokia-MS/Helsinki); Ohad Ben-Cohen; linux- >> > wireless@vger.kernel.org; linux-mmc@vger.kernel.org; linux- >> > omap@vger.kernel.org; Ido Yariv; Mark Brown; linux-arm- >> > kernel@lists.infradead.org; Chikkature Rajashekar, Madhusudhan; Coelho >> > Luciano (Nokia-MS/Helsinki); akpm@linux-foundation.org; San Mehat; Quadros >> > Roger (Nokia-MS/Helsinki); Tony Lindgren; Nicolas Pitre; Pandita, Vikram; >> > Kalle Valo >> > Subject: Re: [PATCH v4 3/8] wireless: wl1271: add platform driver to get >> > board data >> > >> > Hi, >> > >> > On Wed, Aug 11, 2010 at 08:52:54PM +0200, ext DebBarma, Tarun Kanti wrote: >> > >True; however if we go by that argument than we can also assume pdata >> > >is valid, so that we would not need the below check. >> > >> > of course not. You can have devices that just play well with default >> > values or devices where you don't need the flexibility of platform data. >> > That's why we check. >> > >> > platform_device pointers on the other hand, are guaranteed to be always >> > true, if it isn't then you should oops, you deserve to oops because >> > something is really really wrong. >> > >> Sounds perfect! >> What that means is _probe() function makes sense only for cases where we >> have valid platform data because we are returning right at the top if >> pdata is not valid. If this is the case I was curious to know why not >> framework make another check for valid pdata before calling _probe() >> instead of coming all the way to _probe() and then returning! > > Platform devices are not for passing platform data around - they're for > declaring platform hardware devices that we want drivers to handle - > and it depends on the driver whether having platform data is appropriate > or not. > > This proposal is, IMHO, abusing the platform device/driver support to > achieve its own goals. ?I've outlined a far simpler and easiler solution > which avoids this kind of abuse, and given suggestions on how to extend > it to support multiple instances. Thanks, Russell. I'll give your suggestion a spin when I get back (I'm going to be away for some time now with no devices with me).