Re: [PATCH 1/2] spi: spi-fsl-dspi: replace regmap R/W with internal implementation

[Scott Wood <scott.wood@xxxxxxx>]

On 05/09/2016 05:29 AM, Mark Brown wrote:
> On Mon, May 09, 2016 at 08:48:59AM +0000, Yao Yuan wrote:
>> 2, Sometimes regmap will generate some issues. Some regmap issues will cause the DSPI do not working.
>> At 2016.4 we find the DSPI was not work, then we found that the regmap R/W the controller register sometimes not right. 
>> The result is: DSPI can't working with REGMAP API.
>> Although the regmap issues was fast fixed by some giving person. But I'm still tend to use the reliable way.
> 
>> Regmap is nice and Maybe I should try to fix regmap instead of replacing regmap in my driver.
>> But regmap is really very large and complex for DSPI driver.
> 
> Yes, if you find bugs in generic frameworks you should fix them rather
> than just open coding something.  

That's often true, but using regmap to handle endianness is like
swatting flies with a sledgehammer.  Regmap's code is quite (over?)
complicated (e.g. the (user-visible!) difference between
reg_format_endian and val_format_endian is quite confusing) and ideally
people who aren't getting actual value from a buggy and/or awkward
subsystem shouldn't be forced to use/fix it.  We're not talking about
massive duplication here.  We're talking about a set of simple I/O
wrappers (something that many drivers do) with an if-statement.

That said, Yao Yuan, can you try linux-next to see if the regmap
problems have been fixed?  Looking at Linus's tree I don't see how
regmap-mmio would ever give you anything but little-endian if the driver
doesn't specify an endianness (the device tree is only looked at by
regmap_get_val_endian() which wasn't called for regmap-mmio), but that
appears to be fixed in linux-next.

-Scott

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