From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH] eeprom: at24: Add support for large EEPROMs connected to SMBus adapters Date: Wed, 11 Feb 2015 20:01:26 -0800 Message-ID: <20150212040126.GA1691@roeck-us.net> References: <1423067017-27607-1-git-send-email-linux@roeck-us.net> <20150204174723.GB30930@katana> <20150204190819.GA15467@roeck-us.net> <20150204233516.GA1677@katana> <20150205002630.GA396@roeck-us.net> <20150205144028.GA4865@katana> <20150205175326.GA26691@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150205175326.GA26691-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Thu, Feb 05, 2015 at 09:53:26AM -0800, Guenter Roeck wrote: > On Thu, Feb 05, 2015 at 03:40:28PM +0100, Wolfram Sang wrote: > > > > > At the same time multi-master access is quite rare. > > > > > > > > It should still work in those rare cases. A setup of an SoC, an EC > > > > (those like to be masters, as well), and an EEPROM is not very far off. > > > > To clarify: What I meant here is, at24 should also work in those rare > > cases reliably (like the described case of SoC, EC and EEPROM). Your > > patch sacrificies this reliability. > > > But it won't, and it can't. 24c32 should simply not be used in such cases. > Besides, at least on PCs, ACPI should reserve and thus block SMBus access > if it is used by an EC (or IPMI or similar). > > I don't think it should (or even can) be the Linux kernel's responsibility > to ensure that the hardware does not prevent such problems. > Hi Wolfram, I wonder where we are with thisp patch; I don't recall a reply to my previous e-mail. Do you need some more time to think about it ? Otherwise I'll publish an out-of-tree version of the at24 driver with the patch applied on github, for those who might need the functionality provided by this patch. Please let me know. Thanks, Guenter From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932139AbbBLEBl (ORCPT ); Wed, 11 Feb 2015 23:01:41 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:47334 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754693AbbBLEBk (ORCPT ); Wed, 11 Feb 2015 23:01:40 -0500 Date: Wed, 11 Feb 2015 20:01:26 -0800 From: Guenter Roeck To: Wolfram Sang Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] eeprom: at24: Add support for large EEPROMs connected to SMBus adapters Message-ID: <20150212040126.GA1691@roeck-us.net> References: <1423067017-27607-1-git-send-email-linux@roeck-us.net> <20150204174723.GB30930@katana> <20150204190819.GA15467@roeck-us.net> <20150204233516.GA1677@katana> <20150205002630.GA396@roeck-us.net> <20150205144028.GA4865@katana> <20150205175326.GA26691@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150205175326.GA26691@roeck-us.net> User-Agent: Mutt/1.5.23 (2014-03-12) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020204.54DC25A3.01AB,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 3 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 05, 2015 at 09:53:26AM -0800, Guenter Roeck wrote: > On Thu, Feb 05, 2015 at 03:40:28PM +0100, Wolfram Sang wrote: > > > > > At the same time multi-master access is quite rare. > > > > > > > > It should still work in those rare cases. A setup of an SoC, an EC > > > > (those like to be masters, as well), and an EEPROM is not very far off. > > > > To clarify: What I meant here is, at24 should also work in those rare > > cases reliably (like the described case of SoC, EC and EEPROM). Your > > patch sacrificies this reliability. > > > But it won't, and it can't. 24c32 should simply not be used in such cases. > Besides, at least on PCs, ACPI should reserve and thus block SMBus access > if it is used by an EC (or IPMI or similar). > > I don't think it should (or even can) be the Linux kernel's responsibility > to ensure that the hardware does not prevent such problems. > Hi Wolfram, I wonder where we are with thisp patch; I don't recall a reply to my previous e-mail. Do you need some more time to think about it ? Otherwise I'll publish an out-of-tree version of the at24 driver with the patch applied on github, for those who might need the functionality provided by this patch. Please let me know. Thanks, Guenter