Return-path: Received: from 80-190-117-144.ip-home.de ([80.190.117.144]:43009 "EHLO bues.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754777Ab1EGN43 (ORCPT ); Sat, 7 May 2011 09:56:29 -0400 Subject: Re: [PATCH][WAS:bcmai,axi] bcma: add Broadcom specific AMBA bus driver From: Michael =?ISO-8859-1?Q?B=FCsch?= To: =?UTF-8?Q?Rafa=C5=82_Mi=C5=82ecki?= Cc: Arnd Bergmann , linux-wireless@vger.kernel.org, "John W. Linville" , b43-dev@lists.infradead.org, Greg KH , Michael =?ISO-8859-1?Q?B=FCsch?= , Larry Finger , George Kashperko , Arend van Spriel , linux-arm-kernel@lists.infradead.org, Russell King , Andy Botting , linuxdriverproject , "linux-kernel@vger.kernel.org" In-Reply-To: References: <1304632783-8781-1-git-send-email-zajec5@gmail.com> <201105061605.31625.arnd@arndb.de> Content-Type: text/plain; charset="UTF-8" Date: Sat, 07 May 2011 15:55:55 +0200 Message-ID: <1304776555.16344.2.camel@maggie> (sfid-20110507_155634_740980_602D6C78) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Sat, 2011-05-07 at 15:34 +0200, Rafał Miłecki wrote: > 2011/5/6 Rafał Miłecki : > > 2011/5/6 Arnd Bergmann : > >>> +const char *bcma_device_name(u16 coreid) > >>> +{ > >>> + switch (coreid) { > >>> + case BCMA_CORE_OOB_ROUTER: > >>> + return "OOB Router"; > >>> + case BCMA_CORE_INVALID: > >>> + return "Invalid"; > >>> + case BCMA_CORE_CHIPCOMMON: > >>> + return "ChipCommon"; > >>> + case BCMA_CORE_ILINE20: > >>> + return "ILine 20"; > >> > >> It's better to make that a data structure than a switch() statement, > >> both from readability and efficiency aspects. > > > > Well, maybe. We call it only once, at init time. In any case we're > > still waiting for Broadcom to clarify which cores are really used for > > BCMA. > > Arnd: did you have a look at defines at all? > > Most of the defines have values in range 0x800 → 0x837. Converting > this to array means loosing 0x800 u16 entries. We can not use 0x800 > offset, because there are also some defined between 0x000 and 0x800: > #define BCMA_CORE_OOB_ROUTER 0x367 /* Out of band */ > #define BCMA_CORE_INVALID 0x700 > > Oh and there is still: > #define BCMA_CORE_DEFAULT 0xFFF > we could want to include. Then we would loose additional (0xFFF - > 0x837) u16 entries in array. > > I'll just leave this huge "case". As I said, it's called only once on > initialization time. For standard PCI cards there are usually 3-5 > cores, for embedded systems this number can be bigger, but still is > limited with 16 for 1 bus: > #define BCMA_MAX_NR_CORES 16 The compiler does a better job than we do. I'm pretty sure that the compiler will implement this switch statement as a series of small lookup tables combined with some branches, if it thinks it's worth it (also depends on flags and arch). -- Greetings Michael.