Re: [RFC] Add DEV_NOT_IMPLEMENTED error code

Mitsis, Peter <Peter.Mitsis@...>

See [Peter]

-----Original Message-----
From: Andre Guedes [mailto:andre.guedes(a)]
Sent: February-12-16 8:52 AM
To: devel(a)
Subject: [devel] [RFC] Add DEV_NOT_IMPLEMENTED error code

Hi all,

It seems we don't have a consensus about what error code the device driver
should return in case a given driver API is not implemented. If we take a look at
suspend() and resume() functions, which are not implemented by some device
drivers, we can find three different return codes:
- DEV_OK: used in i2c_dw.c, i2c_atmel_sam3.c and gpio_sch.c
- DEV_INVALID_OP: used in pwm_dw.c, gpio_mmio.c and gpio_atmel_sam3.c
- DEV_NO_SUPPORT: used in i2c_qmsi.c and spi_qmsi.c

For these situations, a new error code (DEV_NOT_IMPLEMENTED) seems to be
applicable. If a new error code is not desired, we should agree on one and use it
in all device drivers.


[Peter] - Is there a reason why should not use the existing error code ENOSYS? From the description taken from (pasted below) I would think that it would fit our purposes.

Macro: int ENOSYS
Function not implemented. This indicates that the function called is not implemented at all, either in the C library itself or in the operating system. When you get this error, you can be sure that this particular function will always fail with ENOSYS unless you install a new version of the C library or the operating system.

Peter Mitsis

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