From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753352AbcJCQLr (ORCPT ); Mon, 3 Oct 2016 12:11:47 -0400 Received: from smtp06.smtpout.orange.fr ([80.12.242.128]:36447 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753029AbcJCQLh (ORCPT ); Mon, 3 Oct 2016 12:11:37 -0400 X-ME-Helo: belgarion X-ME-Auth: amFyem1pay5yb2JlcnRAb3JhbmdlLmZy X-ME-Date: Mon, 03 Oct 2016 18:11:29 +0200 X-ME-IP: 90.5.140.104 From: Robert Jarzmik To: Mark Rutland Cc: Rob Herring , Nicolas Pitre , Russell King - ARM Linux , Arnd Bergmann , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] net: smsc911x: add u16 workaround for pxa platforms References: <1475485553-18747-1-git-send-email-robert.jarzmik@free.fr> <1475485553-18747-3-git-send-email-robert.jarzmik@free.fr> <20161003154624.GG7632@leverpostej> X-URL: http://belgarath.falguerolles.org/ Date: Mon, 03 Oct 2016 18:11:23 +0200 In-Reply-To: <20161003154624.GG7632@leverpostej> (Mark Rutland's message of "Mon, 3 Oct 2016 16:46:25 +0100") Message-ID: <87oa319zv8.fsf@belgarion.home> User-Agent: Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mark Rutland writes: > On Mon, Oct 03, 2016 at 11:05:53AM +0200, Robert Jarzmik wrote: >> Add a workaround for mainstone, idp and stargate2 boards, for u16 writes >> which must be aligned on 32 bits addresses. >> >> Signed-off-by: Robert Jarzmik >> --- >> Documentation/devicetree/bindings/net/smsc911x.txt | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/net/smsc911x.txt b/Documentation/devicetree/bindings/net/smsc911x.txt >> index 3fed3c124411..224965b7453c 100644 >> --- a/Documentation/devicetree/bindings/net/smsc911x.txt >> +++ b/Documentation/devicetree/bindings/net/smsc911x.txt >> @@ -13,6 +13,8 @@ Optional properties: >> - reg-io-width : Specify the size (in bytes) of the IO accesses that >> should be performed on the device. Valid value for SMSC LAN is >> 2 or 4. If it's omitted or invalid, the size would be 2. >> +- reg-u16-align4 : Boolean, put in place the workaround the force all >> + u16 writes to be 32 bits aligned > > This property name and description is confusing. > > How exactly does this differ from having reg-io-width = <4>, which is > documented immediately above? reg-io-width specifies the IO size, ie. how many data lines are physically connected from the system bus to the lan adapter. reg-u16-align4 tells that a specific hardware doesn't support 16 bit writes not being 32 bits aligned, or said differently that a "store" 16 bits wide on an address of the format 4*n + 2 deserves a special handling in the driver, while a store 16 bits wide on an address of the format 4*n can follow the simple casual case. I'm pretty open to any name you might suggest, these 3 hardwares I know of are really crazy, you can see them in patch 1/3, in the _SMC_outw_align4() function ... Cheers. -- Robert