From: David Brownell <david-b@pacbell.net>
To: vwool@ru.mvista.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] SPI
Date: Mon, 03 Oct 2005 09:26:46 -0700 [thread overview]
Message-ID: <20051003162646.17F09EE8D2@adsl-69-107-32-110.dsl.pltn13.pacbell.net> (raw)
> >>>It'd be fine if for example your PNX controller driver worked that way
> >>>internally. But other drivers shouldn't be forced to allocate kernel
> >>>threads when they don't need them.
> ...
> FYI in brief: for PREEMPT_RT case all the interrupt handlers are working
> in a separate thread each unless explicitly specified otherwise.
I'm fully aware of that; not that it matters much for folk who aren't
building and deploying systems with PREEMPT_RT.
> We will definitely have less SPI busses => less kernel threads, so I
> doubt there's a rationale in your opinion.
The rationale is simple: you're trying to force one implementation
strategy. Needlessly forcing one strategy, even when others may be
better (I already gave three examples), is a bad idea. QED. :)
> >Well "prevent" may be a bit strong, if you like hopping levels in
> >the software stack. I don't; without such hopping (or without a
> >separate out-of-band mechanism like device tables), I don't see
> >a way to solve that problem.
>
> Aren't the tables you're suggesting also kinda out-of-band stuff?
I just described them that way; yes. They're not layer hopping though;
they preserve the distinctions in roles and responsibilities which help
keep components from interfering with each other.
One general point is that when hardware doesn't support autoconfiguration,
something out-of-band is required to plug that hole. In this case,
those tables can be segmented to handle SPI devices on both mainboards
and add-on boards. Ditto for SPI controllers, but that mostly matters
for developer tools like parport adapters.
- Dave
next reply other threads:[~2005-10-03 16:26 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-03 16:26 David Brownell [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-10-03 5:01 [PATCH] SPI David Brownell
2005-10-03 6:20 ` Vitaly Wool
2005-10-03 4:56 David Brownell
2005-09-30 17:59 David Brownell
2005-09-30 18:30 ` Vitaly Wool
2005-09-30 19:20 ` dpervushin
2005-09-26 11:12 SPI dmitry pervushin
2005-09-27 12:43 ` SPI Greg KH
2005-09-27 14:27 ` [spi-devel-general] SPI dmitry pervushin
2005-09-27 14:35 ` Greg KH
2005-09-27 14:49 ` dmitry pervushin
2005-09-27 14:54 ` Greg KH
2005-09-28 13:14 ` [PATCH] SPI dmitry pervushin
2005-08-08 23:07 [PATCH] spi david-b
2005-08-09 9:38 ` Mark Underwood
2005-07-10 20:01 [PATCH 3/3] kconfig: linux.pot for all arch Egry Gábor
2005-08-08 9:12 ` [PATCH] spi dmitry pervushin
2005-08-08 10:41 ` Jiri Slaby
2005-08-08 13:16 ` Mark Underwood
2005-08-08 16:41 ` dmitry pervushin
2005-08-08 18:51 ` Mark Underwood
2005-08-08 14:55 ` Greg KH
2005-08-08 17:35 ` Marcel Holtmann
2005-08-08 17:47 ` Marc Singer
2005-08-09 17:54 ` Andy Isaacson
2005-08-09 19:05 ` Marc Singer
2005-08-09 19:29 ` Andy Isaacson
2005-08-15 7:51 ` Denis Vlasenko
2005-08-08 22:58 ` Andrew Morton
2005-08-10 13:10 ` Pavel Machek
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