linux-kernel - Re: [PATCH 6/6 v5] regmap: Incorporate the regcache core into regmap

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Date:	Mon, 19 Sep 2011 17:57:49 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>
CC:	linux-kernel@...r.kernel.org,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Liam Girdwood <lrg@...com>,
	Graeme Gregory <gg@...mlogic.co.uk>,
	Samuel Oritz <sameo@...ux.intel.com>
Subject: Re: [PATCH 6/6 v5] regmap: Incorporate the regcache core into regmap

On 09/19/2011 03:34 PM, Dimitris Papastamos wrote:
> This patch incorporates the regcache core code into regmap.  All previous
> patches have been no-ops essentially up to this point.
> 
> The bulk read operation is not supported by regcache at the moment.  This
> will be implemented incrementally.
> 
> Signed-off-by: Dimitris Papastamos <dp@...nsource.wolfsonmicro.com>
> Tested-by: Lars-Peter Clausen <lars@...afoo.de>

Hi

Two issues with this version.

> [...]
> @@ -290,6 +302,12 @@ static int _regmap_write(struct regmap *map, unsigned int reg,
>  	int ret;
>  	BUG_ON(!map->format.format_write && !map->format.format_val);
>  
> +	if (!map->cache_bypass) {
> +		ret = regcache_write(map, reg, val);
> +		if (!ret || map->cache_only)
> +			return 0;

The hw write shouldn't be skipped if the cache write is successful. We should
only exit here if cache_only is set.

I also wonder if we should pass the return value of regcache_write on to the
caller if cache_only is set.

Btw. what should happen if both cache_bypass and cache_only are set? Or is that
an invalid configuration?

> +	}
> +
>  	trace_regmap_reg_write(map->dev, reg, val);
>  
>  	if (map->format.format_write) {
> @@ -428,6 +446,14 @@ int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val)
>  
>  	mutex_lock(&map->lock);
>  
> +	if (!map->cache_bypass) {
> +		ret = regcache_read(map, reg, val);
> +		if (!ret) {
> +			mutex_unlock(&map->lock);
> +			return 0;
> +		}
> +	}

This should go into _regmap_read. Otherwise regmap_update_bits will always use
a hw read.

Also if cache_only is set I guess we shouldn't fallback to a hw read.
> +
>  	ret = _regmap_read(map, reg, val);
>  
>  	mutex_unlock(&map->lock);

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