On 8/16/19 4:30 PM, Dan Murphy wrote:
>>> +static u32 tcan4x5x_read_reg(struct m_can_classdev *cdev, int reg)
>>> +{
>>> + struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)cdev->device_data;
>>> + u32 val;
>>> +
>>> + tcan4x5x_check_wake(priv);
>> Do you have to call this every time you access the Chip? Can you move
>> this into the open() function?
>
> Yes we have to call this as the device will time out without bus activity.
>From my naive point of view, I'd put the device into normal mode in the
ndo_open callback.
> The only way to wake it up is through a pulse of the wake up GPIO. SPI
> interface is disabled in sleep mode.
Looking at figure 23 in the datasheet the only transition from normal
mode to any other mode is via writing MO = 01 (standby) or MO = 00 (sleep).
I think with MO they mean the MODE_SEL bits of register 0x800.
> So the function tests to see if the device went to sleep and if it is it
> wakes it up.
>
> Putting this in the open function only wakes the device up initially.
>
> Section 8.4.3 of the data sheet [1]
regards,
Marc
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