linux-kernel - Re: [PATCH] regmap: Allow read_reg

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Date:	Tue, 30 Sep 2014 16:18:48 -0500
From:	Dan Murphy <dmurphy@...com>
To:	Lars-Peter Clausen <lars@...afoo.de>, <broonie@...nel.org>,
	<gregkh@...uxfoundation.org>
CC:	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>
Subject: Re: [PATCH] regmap: Allow read_reg_mask to be 0

Lars

On 09/30/2014 04:03 PM, Lars-Peter Clausen wrote:
> On 09/30/2014 06:07 PM, Dan Murphy wrote:
>> There may be spi devices that do not require a
>> register read mask to read the registers.
>>
>> Currently the code sets the read mask based on
>> a non-zero value passed in from the driver or if that
>> value is 0 sets the read mask to 0x80.
>
> It only sets it to the bus default if both read_flag_mask and write_flag_mask are 0. The assumption is that both of them being zero is a invalid configuration and either of them (or both) have to be non-zero for proper operation, since otherwise the device can't tell the difference between a read and a write.
>
> Do you have a device where both the read and the write mask is 0?
>
> - Lars

Yes I do have a device that the read/write mask are both 0.

The device, which is already in production, has a specific control register that sets either the reading or writing of the rest of the registers.

Here is the data sheet

http://www.ti.com/lit/ds/symlink/afe4403.pdf

See page 61 control0.

Driver is written for this part just want to get this lead patch in or maybe an alternate solution.

Dan

-- 
------------------
Dan Murphy

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