linux-kernel - Re: [alsa-devel] [PATCH 1/2] regmap: cache: Fix regcache_sync_block for non-autoincrementing devices

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Date:	Tue, 26 Aug 2014 16:21:07 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:	alsa-devel@...a-project.org, Mark Brown <broonie@...nel.org>,
	linux-kernel@...r.kernel.org, Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [alsa-devel] [PATCH 1/2] regmap: cache: Fix regcache_sync_block for	non-autoincrementing devices

At Tue, 26 Aug 2014 17:03:12 +0300,
Jarkko Nikula wrote:
> 
> Commit 75a5f89f635c ("regmap: cache: Write consecutive registers in a single
> block write") expected that autoincrementing writes are supported if
> hardware has a register format which can support raw writes.
> 
> This is not necessarily true and thus for instance rbtree sync can fail when
> there is need to sync multiple consecutive registers but block write to
> device fails due not supported autoincrementing writes.
> 
> Fix this by spliting raw block sync to series of single register writes for
> devices that don't support autoincrementing writes.

Wouldn't it suffice to correct regmap_can_raw_write() to return false
if map->use_single_rw is set?

Takashi

> 
> Signed-off-by: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
> ---
> I noticed this with Realtek RT5642 audio codec which didn't resume properly
> since first block write having more data than for single register failed to
> not acknowledged I2C write during regcache_sync(). Chip acknowledges device
> address, register address and two data bytes for its word size registers but
> next data byte is not which then causes aborted I2C transfer and aborted
> register sync.
> ---
>  drivers/base/regmap/regcache.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
> index 29b4128da0b0..54707e586ac8 100644
> --- a/drivers/base/regmap/regcache.c
> +++ b/drivers/base/regmap/regcache.c
> @@ -629,6 +629,7 @@ static int regcache_sync_block_raw_flush(struct regmap *map, const void **data,
>  {
>  	size_t val_bytes = map->format.val_bytes;
>  	int ret, count;
> +	unsigned int i;
>  
>  	if (*data == NULL)
>  		return 0;
> @@ -640,7 +641,18 @@ static int regcache_sync_block_raw_flush(struct regmap *map, const void **data,
>  
>  	map->cache_bypass = 1;
>  
> -	ret = _regmap_raw_write(map, base, *data, count * val_bytes);
> +	if (!map->use_single_rw) {
> +		ret = _regmap_raw_write(map, base, *data, count * val_bytes);
> +	} else {
> +		for (i = 0; i < count; i++) {
> +			ret = _regmap_raw_write(map,
> +						base + (i * map->reg_stride),
> +						*data + (i * val_bytes),
> +						val_bytes);
> +			if (ret != 0)
> +				break;
> +		}
> +	}
>  
>  	map->cache_bypass = 0;
>  
> -- 
> 2.1.0
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@...a-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> 
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