linux-kernel - Re: mc13xxx-core: kernel hangs after 'regmap

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Message-Id: <201205242306.09053.marc@cpdesign.com.au>
Date:	Thu, 24 May 2012 23:06:08 +1000
From:	Marc Reilly <marc@...esign.com.au>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Shawn Guo <shawn.guo@...escale.com>,
	"Uwe Kleine-König" 
	<u.kleine-koenig@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Sascha Hauer <kernel@...gutronix.de>,
	Philippe Rétornaz <philippe.retornaz@...l.ch>,
	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: mc13xxx-core: kernel hangs after 'regmap_read'

Hi,


> > > Yes, that's been missed in the addition of padding.  We should also be
> > > using DIV_ROUND_UP() which we aren't at the minute.
> > 
> > That would break, in _regmap_read_raw():
> > 	ret = map->bus->read(map->bus_context, map->work_buf,
> > 	
> > 			     map->format.reg_bytes + map->format.pad_bytes,
> > 			     val, val_len);
> > 
> > If pad_bytes was 1 here, then the register size would end up being 2
> > bytes.
> 
> The above is about buf_size...  pad_bytes isn't in the quoted text which
> is the issue.

I misunderstood where you intended to put the DIV_ROUND_UP, sorry.

Something like this:

--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -246,7 +246,9 @@ struct regmap *regmap_init(struct device *dev,
 		map->lock = regmap_lock_mutex;
 		map->unlock = regmap_unlock_mutex;
 	}
-	map->format.buf_size = (config->reg_bits + config->val_bits) / 8;
+	map->format.buf_size = DIV_ROUND_UP(config->reg_bits +
+					    config->val_bits +
+					    config->pad_bits % 8, 8);
 	map->format.reg_bytes = DIV_ROUND_UP(config->reg_bits, 8);
 	map->format.pad_bytes = config->pad_bits / 8;
 	map->format.val_bytes = DIV_ROUND_UP(config->val_bits, 8);
-- 

Hope that fixes things.

Cheers,
Marc
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