Messages in this thread | | | Subject | Re: [RFC PATCH 1/2] ASoC: soc-component: add snd_soc_component_read/write_field() | From | Srinivas Kandagatla <> | Date | Tue, 26 Jan 2021 14:03:29 +0000 |
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On 26/01/2021 13:36, Mark Brown wrote: > On Tue, Jan 26, 2021 at 12:20:19PM +0000, Srinivas Kandagatla wrote: > >> +#define __soc_component_field_shift(x) (__builtin_ffs(x) - 1) > > Why not have this be a static inline?
Sure, that makes it even better to validate the mask aswell!
> >> +unsigned int snd_soc_component_read_field(struct snd_soc_component *component, >> + unsigned int reg, unsigned int mask) >> +{ >> + unsigned int val; >> + >> + mutex_lock(&component->io_mutex); >> + val = soc_component_read_no_lock(component, reg); >> + if (mask) >> + val = (val & mask) >> __soc_component_field_shift(mask); > > I don't understand why this is open coding the locking when it's just a > simple read and then shift?
I agree! something like this should be good I guess:
unsigned int snd_soc_component_read_field(...) { unsigned int val;
val = snd_soc_component_read(component, reg);
val = (val & mask) >> __soc_component_field_shift(mask);
return val; }
> >> + mutex_lock(&component->io_mutex); >> + >> + old = soc_component_read_no_lock(component, reg); >> + >> + val = val << __soc_component_field_shift(mask); >> + >> + new = (old & ~mask) | (val & mask); >> + >> + change = old != new; >> + if (change) >> + ret = soc_component_write_no_lock(component, reg, new); >> + >> + mutex_unlock(&component->io_mutex); > > This needs the lock as it's a read/modify/write but could also be > implemented in terms of the existing update_bits() operation rather than > open coding it. True!, we could simplify this to :
int snd_soc_component_write_field(struct snd_soc_component *component, unsigned int reg, unsigned int mask, unsigned int val) { val = (val << __soc_component_field_shift(mask)) & mask;
return snd_soc_component_update_bits(component, reg, mask, val); }
Does that look okay to you?
--srini >
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