[PATCH 01/23] ARM: OMAP2+: clock: move clock provider infrastructure to clock driver

[Tomi Valkeinen]

On 26/01/15 17:49, Tony Lindgren wrote:

>> I'm not sure if I miss something, but regmap_write does not protect from
>> problems if there are multiple users for the same registers. You need to
>> use regmap_update_bits() to get a protected read/write sequence, in
>> which you can change only the bits that you want to change.
> 
> To me it seems that issue can be fixed by making all the code use regmap.
> AFAIK that should work for the legacy code too.

Even if everybody uses regmap, doing

v = regmap_read()
modify v
regmap_write(v)

is racy. regmap_update_bits() has to be used to protect the read/write
sequence. Which may be somewhat challenging at times with some strange
registers, the like Roger Q encountered recently related to CAN.

 Tomi


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