From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Oskar Schirmer" Subject: Re: [PATCH] ad7877: fix spi word size to 16 bit Date: Mon, 17 May 2010 09:29:36 +0200 Message-ID: <20100517072935.GA14891@emlix.com> References: <1273142265-11929-1-git-send-email-os@emlix.com> <4BE3E02E.1090500@emlix.com> <20100513075335.GD30110@core.coreip.homeip.net> <20100515181523.GA3081@emlix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx1.emlix.com ([193.175.82.87]:52073 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753982Ab0EQH3l (ORCPT ); Mon, 17 May 2010 03:29:41 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Mike Frysinger Cc: Oskar Schirmer , Dmitry Torokhov , Daniel =?utf-8?B?R2zDtmNrbmVy?= , Andrew Morton , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Oliver Schneidewind , Michael Hennerich On Sun, May 16, 2010 at 15:25:34 -0400, Mike Frysinger wrote: > On Sat, May 15, 2010 at 14:15, Oskar Schirmer wrote: > > On Thu, May 13, 2010 at 00:53:35 -0700, Dmitry Torokhov wrote: > >> On Fri, May 07, 2010 at 02:23:07PM -0400, Mike Frysinger wrote: > >> > On Fri, May 7, 2010 at 05:41, Daniel Gl=C3=B6ckner wrote: > >> > > On 05/06/2010 08:26 PM, Mike Frysinger wrote: > >> > >> i think it'd be a better idea to do something like: > >> > >> =C2=A0 if (spi->bits_per_word !=3D 16) { > >> > >> =C2=A0 =C2=A0 if (spi->bits_per_word) { > >> > >> =C2=A0 =C2=A0 =C2=A0 dev_err(&spi->dev, "Invalid SPI settings= ; bits_per_word must be 16\n"); > >> > >> =C2=A0 =C2=A0 =C2=A0 return -EINVAL; > >> > >> =C2=A0 =C2=A0 } > >> > >> =C2=A0 =C2=A0 spi->bits_per_word =3D 16; > >> > >> =C2=A0 =C2=A0 spi_setup(spi); > >> > >> =C2=A0 } > >> > > > >> > > There is no way to set bits_per_word using struct spi_board_in= fo. The > >> > > description of that structure in spi.h explicitly lists the wo= rdsize as > >> > > one of the parameters drivers should set themself in probe(). > >> > > > >> > > Only struct bfin5xx_spi_chip allows to set this value in the b= oard code. > >> > > >> > an obvious shortcoming in the SPI framework that should be fixed= , but > >> > that doesnt make any difference to the above code now does it ? = =C2=A0it'll > >> > operate correctly regardless of the SPI bus master. > >> > >> So is the updated patch coming? > > > > The basic question I see is, whether it is in the > > responsibility of ad7877 to check a wrong setting > > possibly caused in board specific code. If so, > > then the proposal by Mike should be used, but if not > > so, it would introduce unneeded code. > > > > Remember: both versions end up in correctly setting > > bits_per_word, with the difference merely in feedback > > level. >=20 > imo, unsupported board settings should always be detected & rejected. > all SPI master drivers do this (detect & reject unsupported SPI slave > settings). please note, that bits_per_word is not a board setting, it's a demand of the device. consequently, there is no one to set unsupported values and thus none to be detected. the only architecture setting bits_per_word thru spi_chip is blackfin, but I cannot see a good reason, why the board settings should engage with a fixed demand of the device? Oskar --=20 oskar schirmer, emlix gmbh, http://www.emlix.com fon +49 551 30664-0, fax -11, bahnhofsallee 1b, 37081 g=C3=B6ttingen, g= ermany sitz der gesellschaft: g=C3=B6ttingen, amtsgericht g=C3=B6ttingen hr b = 3160 gesch=C3=A4ftsf=C3=BChrer: dr. uwe kracke, ust-idnr.: de 205 198 055 emlix - your embedded linux partner -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html