linux-kernel - Re: [PATCH 1/2] regmap: Allow installing custom reg_update

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Message-ID: <alpine.DEB.2.10.1510010826450.21737@jring-w510-7m3g.gridpoint.com>
Date:	Thu, 1 Oct 2015 08:29:19 -0400 (EDT)
From:	Jon Ringle <jon@...gle.org>
To:	Mark Brown <broonie@...nel.org>
cc:	jon@...gle.org, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 1/2] regmap: Allow installing custom reg_update_bits
 function



On Thu, 1 Oct 2015, Mark Brown wrote:

> On Thu, Oct 01, 2015 at 02:33:06AM -0400, jon@...gle.org wrote:
> 
> > @@ -2509,6 +2510,10 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
> >  	int ret;
> >  	unsigned int tmp, orig;
> >  
> > +	if (map->reg_update_bits)
> > +		return map->reg_update_bits(map->bus_context, reg, mask, val,
> > +					    change, force_write);
> > +
> >  	ret = _regmap_read(map, reg, &orig);
> >  	if (ret != 0)
> >  		return ret;
> 
> This completely bypasses and therefore breaks the cache infrastructure.
> 

Hi Mark,

Right after sending the v2 patch, I realized that calling the 
custom reg_update_bits would only be applicable for registers that are 
marked as volatile. Would the following solution be acceptable (it would 
also simplify the regmap_update_bits in the encx24j600 driver):

	if (regmap_volatile(map, reg) && map->reg_update_bits) {
		return map->reg_update_bits(map->bus_context, reg, mask, 
		                            val, change, force_write);
		
The cache state should not matter for volatile registers, right?

-Jon
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