[U-Boot] [PATCH 4/8] Add a poll function to monitor events

[Wolfgang Denk]

Dear Hatim Ali,

In message <1355223289-15685-5-git-send-email-hatim.rv at samsung.com> you wrote:
> From: Akshay Saraswat <akshay.s at samsung.com>
> 
> Adding a generic polling function to continuously monitor events and
> trigger actions corresponding to them.
> 
> Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
> Acked-by: Simon Glass <sjg at chromium.org>
> 
> diff --git a/README b/README
> index 037513a..0e4083c 100644
> --- a/README
> +++ b/README
> @@ -2841,6 +2841,13 @@ Configuration Settings:
>  		the application (usually a Linux kernel) when it is
>  		booted
>  
> +- CONFIG_BOARD_POLL
> +	There are various scenarios in which parallel-thread like
> +	polling is required to monitor status of variety of devices.
> +	For such situations CONFIG_BOARD_POLL shall be enabled
> +	and funtion call board_poll_devices() from console_tstc()
> +	will then poll for the device status as defined inside function.


Sorry, but I dislike this, for a number of reasons.

1) There is, and has always been, a very basic design decision, that
   U-Boot is strictly single-tasking, i. e. we don't have any kind of
   "background activities" goind on.  Your introduction of a device
   polling mechanism violates this principle.

   I don't say that this is unacceptable, but we have to be aware that
   this is a far-reaching decision, so we should consider it very
   carefully.

   If anything like this gets implemented, it has to be done in a way
   that will be general enough to be useful to others as well.

2) U-Boot is a boot loader, not an OS.  Do we really need continuous
   temperature management in U-Boot?  I think not.  After all, our
   main purpose is to boot an OS, and do that as fast as possible.
   The majority of users will see U-Boot running only for a few
   milliseconds, and only when they boot the device - which may be
   very seldom.

   So what exactly do we need this for?

3) Your hooking of a device polling into console_tstc() is broken by
   design.   It may be sufficient for the specific use case you have
   in mind here, but it is totally useless for any other purpose.

This needs a lot of additional thought, and major changes to the
implementation.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Without facts, the decision cannot be made logically. You  must  rely
on your human intuition.
	-- Spock, "Assignment: Earth", stardate unknown