Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761267Ab0FRNcZ (ORCPT ); Fri, 18 Jun 2010 09:32:25 -0400 Received: from mail-ww0-f46.google.com ([74.125.82.46]:55816 "EHLO mail-ww0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761089Ab0FRNcX (ORCPT ); Fri, 18 Jun 2010 09:32:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=EfLmngI9/hm5to2KZWYU7L5OjzDJQhE+vV2mdLR9AyR0pHU3xYO0MzdhZ14gPrg5M5 9NBtOEFDlfq6f4EVDSf7r1Ljc+y/MmoDpIdQwwy6fdX4aqLwyMdNxqxbNJ/mxZyK4ArS bU40t6E3hpRPRQvekUvvoPlVHg+RqSSwMvwxg= Date: Fri, 18 Jun 2010 17:32:12 +0400 From: Anton Vorontsov To: Barry Song <21cnbao@gmail.com> Cc: Andrew Morton , David Brownell , David Woodhouse , Artem Bityutskiy , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, uclinux-dist-devel@blackfin.uclinux.org Subject: Re: [PATCH 1/2] mtd: m25p80: Rework probing/JEDEC code Message-ID: <20100618133212.GA5276@oksana.dev.rtsoft.ru> References: <20090818214449.GA12848@oksana.dev.rtsoft.ru> <20090818214622.GA22651@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3300 Lines: 92 On Sat, Jun 12, 2010 at 02:27:12PM +0800, Barry Song wrote: > On Wed, Aug 19, 2009 at 5:46 AM, Anton Vorontsov > wrote: > > > > Previosly the driver always tried JEDEC probing, assuming that non-JEDEC > > chips will return '0'. But truly non-JEDEC chips (like CAT25) won't do > > that, their behaviour on RDID command is undefined, so the driver should > > not call jedec_probe() for these chips. > > > > Also, be less strict on error conditions, don't fail to probe if JEDEC > > found a chip that is different from what platform code told, instead > > just print some warnings and use an information obtained via JEDEC. In > This patch caused a problem: > even though the external flash doesn't exist, it will still pass the > probe() and be registerred into kernel and given the partition table. > You may refer to this bug report: > http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=5975&start=0 Thanks for the report. There's little we can do about it. Platform code asked us to register the device, and JEDEC probing of M25Pxx chips isn't reliable (thanks to various vendors that make these JEDEC and non-JEDEC variants), so the best thing we can do is to register the chip anyway. OTOH, if the board pulls MISO line up, then the following patch should help. If this won't work, we'll have to add some flag to the platform data, i.e. to force JEDEC probing, and not trust platform data. Not-yet-Signed-off-by: Anton Vorontsov --- diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c index 81e49a9..a307929 100644 --- a/drivers/mtd/devices/m25p80.c +++ b/drivers/mtd/devices/m25p80.c @@ -16,6 +16,7 @@ */ #include +#include #include #include #include @@ -723,7 +724,7 @@ static const struct spi_device_id *__devinit jedec_probe(struct spi_device *spi) if (tmp < 0) { DEBUG(MTD_DEBUG_LEVEL0, "%s: error %d reading JEDEC ID\n", dev_name(&spi->dev), tmp); - return NULL; + return ERR_PTR(tmp); } jedec = id[0]; jedec = jedec << 8; @@ -737,7 +738,7 @@ static const struct spi_device_id *__devinit jedec_probe(struct spi_device *spi) * exist for non-JEDEC chips, but for compatibility they return ID 0. */ if (jedec == 0) - return NULL; + return ERR_PTR(-EEXIST); ext_jedec = id[3] << 8 | id[4]; @@ -749,7 +750,7 @@ static const struct spi_device_id *__devinit jedec_probe(struct spi_device *spi) return &m25p_ids[tmp]; } } - return NULL; + return ERR_PTR(-ENODEV); } @@ -794,9 +795,11 @@ static int __devinit m25p_probe(struct spi_device *spi) const struct spi_device_id *jid; jid = jedec_probe(spi); - if (!jid) { + if (IS_ERR(jid) && PTR_ERR(jid) == -EEXIST) { dev_info(&spi->dev, "non-JEDEC variant of %s\n", id->name); + } else if (IS_ERR(jid)) { + return PTR_ERR(jid); } else if (jid != id) { /* * JEDEC knows better, so overwrite platform ID. We -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/