[U-Boot] Device cleanup before starting OS (Linux)

[Stefan Roese]

Hi Simon,

On 01.03.2017 06:40, Simon Glass wrote:
> On 28 February 2017 at 09:32, Stefan Roese <sr at denx.de> wrote:
>>
>> Hi!
>>
>> I'm currently trying to add some code to stop (DMA) buffer usage
>> in the Marvell mvpp2 ethernet driver, that should only be
>> executed once, before the OS is started - stop() does not work
>> easily for me here. I've found the weak function
>> "board_quiesce_devices()", which is already used for
>> such cases. But since you are not fond of weak functions
>> (I totally agree here, this is far from perfect) and already
>> suggested some kind of "finalize" DM API call, I'm wondering
>> if I should introduce this new API call for such cases and use
>> it in the ethernet driver.
>>
>> So what is your opinion about this? Should I add such a
>> finalize DM function and call it from the arch/.../bootm
>> code? Or do you have other suggestions on how to handle
>> such driver specific last-stage (pre OS) calls?
> 
> Is it possible to use the device's remove() method?

I also thought about this of course. Using remove has the
following disadvantages, that I currently can think of:

- The remove functions of all devices are called, adding
  to the bootup time

- Since all devices are removed, serial (and other) output
  is not available (for debug purposes) any more

It should be possible to add a DM flag to enable this pre-OS
device remove, which could be enabled on a per-device basis.
This way we don't need another API function. But still I
need to hook this pre-OS "remove" into arch/.../bootm.

What do you think?

Thanks,
Stefan