Re: [PATCH] regmap: Allow read_reg_mask to be 0

From: Dan Murphy
Date: Tue Sep 30 2014 - 16:19:29 EST


Thanks for the review

On 09/30/2014 12:25 PM, Mark Brown wrote:
> On Tue, Sep 30, 2014 at 11:07:00AM -0500, Dan Murphy wrote:
>> - if (config->read_flag_mask || config->write_flag_mask) {
>> + if (config->read_flag_mask == REGMAP_NO_READ_MASK)
>> + map->read_flag_mask = 0x00;
>> + else if (config->read_flag_mask)
> This breaks the symmetry in handling of read and write masks which isn't
> great, please make the equivalent update for the write mask too.

Hmmm. If I make the similar change for the write mask I will be adding dead
code as write_flag_mask is not defaulted by the bus like the read_flag_mask which is
defaulted to 0x80 in the regmap-spi code. The i2c code does not make this assumption.

The original code did not seem to have symmetry as the only instance
that write_flag_mask is modified is if it is non-zero.

Let me know what you think. I can add the code to make it more symmetrical but
we may be adding code that is dead. If I remove the defaulted read_flag_mask value out
of the spi driver then I will need to find every spi device that needs that flag and set it.
IMHO that would be really messy and probably mess us some drivers.

>> +#define REGMAP_NO_READ_MASK 0xff
> An actual out of band value might be preferable here though that'd
> involve changing the type and more checking so perhaps inessential.

Thought about making this -1 with a variable change but that seemed
really drastic where a value of 0xff seems to be a value that no one should use.


Dan Murphy

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