Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:63187 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934387Ab2HWUxf (ORCPT ); Thu, 23 Aug 2012 16:53:35 -0400 Received: by ialo24 with SMTP id o24so1991282ial.19 for ; Thu, 23 Aug 2012 13:53:34 -0700 (PDT) Message-ID: <5036984A.6060004@lwfinger.net> (sfid-20120823_225402_022699_5F3757EF) Date: Thu, 23 Aug 2012 15:53:30 -0500 From: Larry Finger MIME-Version: 1.0 To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= CC: Arend van Spriel , "Saul St. John" , linux-wireless@vger.kernel.org, "John W. Linville" Subject: Re: [PATCH 2/2] bcma: expose cc sprom to sysfs References: <20120816190616.GE6726@eris.garyseven.net> <502E4B70.5090900@broadcom.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 08/23/2012 02:44 PM, Rafał Miłecki wrote: > 2012/8/17 Arend van Spriel : >> On 08/16/2012 09:06 PM, Saul St. John wrote: >>> >>> On BCMA devices with a ChipCommon core of revision 31 or higher, the >>> device >>> SPROM can be accessed through CC core registers. This patch exposes the >>> SPROM on such devices for read/write access as a sysfs attribute. >>> >>> Tested on a MacBookPro8,2 with BCM4331. >>> >>> Cc: Rafał Miłecki >>> Cc: John W. Linville >>> Signed-off-by: Saul St. John >> >> >> Hi Saul, >> >> I was still planning to come back to your reply on August 14. Just wanted to >> reply to this patch as I still feel it is a bad thing to open up the sprom >> as a whole. I can see the use-cases you mentioned as useful, but maybe we >> can get a specific solution for that. > > I agree with Arend's doubts, on the other hand it would be nice to > provide some workaround for that stupid HP wifi blacklisting. > > Providing a way to overwrite just a vendor is really close to allowing > overwriting anything. In that case we probably should just allow > writing whole SPROM... Which again, is sth some want to avoid. > > > I wonder if we could write some user-space tool for writing SPROM. > Accessing ChipCommon registers is quite trivial, the thing I'm not > familiar with is accessing PCIE Wifi card registers. I know there are > tools for accessing GPU card regs. They work really well, I wonder if > we can use the same method for Wifi cards? > If so, we could write user-space app and keep this out of kernel. > Maybe we could even extend that tool to cover ssb cards and drop SPROM > on SSB writing support from kernel? This idea sounds good to me. The only valid use of the ssb SPROM writing was when we found some G-PHY cards that had the BT compatibility setting wrong. Now there is a set of quirks that eliminate that need for rewriting the SPROM. With a separate utility, we can control what parameters can be changed. The vendor codes are one possibility. What else would be useful? I have seen changing the MAC address be mentioned, but I would argue against that. There are too many possibilities for misuse. Larry