Re: RE: RE: [PATCH v3 1/2] can: m_can: Move mram init to mcan device setup

[Marc Kleine-Budde]

On 01.12.2022 09:40:50, Vivek Yadav wrote:
> > That probably depends on you power management. If I add a regulator
> > to power the external tcan4x5x chip and power it up during open(), I
> > need to initialize the RAM.
> > 
> Thanks for the clarification,
>
> There is one doubt for which I need clarity if I add ram init in
> m_can_chip_config.
> 
> In the current implementation, m_can_ram_init is added in the probe
> and m_can_class_resume function.
>
> If I add the ram init function in chip_config which is getting called
> from m_can_start, then m_can_init_ram will be called two times, once
> in resume and next from m_can_start also.

As m_can_start() is called from resume, remove the direct call to
m_can_init_ram() from m_can_class_resume().

> Can we add ram init inside the m_can_open function itself? Because it
> is independent of m_can resume functionality.

See above.

mainline implementation:

m_can_class_resume()
        -> m_can_init_ram()

m_can_open()
        -> m_can_start()
        -> m_can_chip_config()
        -> ops->init
                m_can_init_ram() (for tcan only)


proposed:

m_can_class_resume()
        -> m_can_start()
        -> m_can_chip_config()
        -> m_can_init_ram()

m_can_open()
        -> m_can_start()
        -> m_can_chip_config()
        -> m_can_init_ram()

In mainline m_can_init_ram() is called for the tcan during open(). So if
you call m_can_init_ram() from m_can_chip_config(), remove it from the
tcan's tcan4x5x_init() functions, and from m_can_class_resume() it
should only be called once for open and once for resume.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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