linux-kernel - Re: [PATCH 3/5] mfd: ti_am335x_tscadc: Don't read back REG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140106093525.GE23772@lee--X1>
Date:	Mon, 6 Jan 2014 09:35:25 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Zubair Lutfullah <zubair.lutfullah@...il.com>,
	Felipe Balbi <balbi@...com>, linux-iio@...r.kernel.org,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] mfd: ti_am335x_tscadc: Don't read back REG_SE

On Thu, 19 Dec 2013, Sebastian Andrzej Siewior wrote:

> The purpose of reg_se_cache has been defeated. It should avoid the
> read-back of the register to avoid the latency and the fact that the
> bits are reset to 0 after the individual conversation took place.
> 
> The reason why this is required like this to work, is that read-back of
> the register removes the bits of the ADC so they do not start another
> conversation after the register is re-written from the TSC side for the
> update.
> To avoid the not required read-back I introduce a "set once" variant which
> does not update the cache mask. After the conversation completes, the
> bit is removed from the SE register anyway and we don't plan a new
> conversation "any time soon". The current set function is renamed to
> set_cache to distinguish the two operations.
> This is a small preparation for a larger sync-rework.
> 
> Acked-by: Lee Jones <lee.jones@...aro.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  drivers/iio/adc/ti_am335x_adc.c           |  4 ++--
>  drivers/input/touchscreen/ti_am335x_tsc.c |  4 ++--

Just need Dmitry's Ack now.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/