linux-kernel - Re: [PATCH 4/4] mfd: arizona: Use new regmap features for manual register patch

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Date:	Tue, 25 Feb 2014 14:27:43 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:	broonie@...nel.org, gregkh@...uxfoundation.org,
	sameo@...ux.intel.com, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH 4/4] mfd: arizona: Use new regmap features for manual
 register patch

On Tue, 25 Feb 2014, Charles Keepax wrote:

> On the wm5102 the register patches are applied manually, rather than by
> the regmap core. This application is wrapped in calls to
> regcache_cache_bypass. However, this is dangerous as other threads may
> be accessing the hardware at the same time as the pm_runtime operations
> and if they do so during the period whilst cache_bypass is enabled those
> writes will miss the cache when they shouldn't.
> 
> Apply the register patch using the new regmap_multi_reg_write_bypassed
> function to avoid this problem. Also remove the call to
> regcache_cache_bypass from the hardware patch application as it is
> unneeded there and creates a similar window for writes to miss the
> cache.
> 
> Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> ---
>  drivers/mfd/arizona-core.c  |    4 ----
>  drivers/mfd/wm5102-tables.c |   21 ++++-----------------
>  2 files changed, 4 insertions(+), 21 deletions(-)

Acked-by: Lee Jones <lee.jones@...aro.org>

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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