Messages in this thread | | | Subject | Re: [PATCH 01/10] i2c: add suspended flag and accessors for i2c adapters | From | Hans de Goede <> | Date | Wed, 19 Dec 2018 19:36:54 +0100 |
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Hi,
On 19-12-18 18:22, Lukas Wunner wrote: > On Wed, Dec 19, 2018 at 05:48:17PM +0100, Wolfram Sang wrote: >> +static inline void i2c_mark_adapter_suspended(struct i2c_adapter *adap) >> +{ >> + i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER); >> + set_bit(I2C_ALF_IS_SUSPENDED, &adap->locked_flags); >> + i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER); >> +} > > This looks like a duplication of the is_suspended flag in struct dev_pm_info. > Any reason why you can't use that? If so, it would be good to document the > reason in the commit message.
Oh, that is a very good point and that one only gets set on system suspend and not on resume suspend, working around the problems with the i2c-designware driver.
I think this might be as simple as adding:
if (WARN_ON(adap->dev.parent->power.is_suspended)) return -ESHUTDOWN;
To __i2c_transfer (and document the -ESHUTDOWN) combined with removing all the now no longer DIY code from various bus drivers.
Regards,
Hans
> > If the point is to constrain refusal of transfers in suspended state to > certain drivers, those drivers could opt in to that functionality by > setting a flag, and the i2c core could then gate refusal based on > that flag and the is_suspended flag in struct dev_pm_info. > > Also, why is it necessary to take a lock to perform an atomic bitop? > (Sorry if that's a dumb question, seems non-obvious to me.) > > Thanks, > > Lukas >
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