From: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> To: Linus Walleij <linus.ml.walleij-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Cc: spi mailing list <spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>, Ken Mills <ken.k.mills-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> Subject: Re: [PATCH] Add support for slave controllers plus sysfs entries for power management Date: Tue, 16 Feb 2010 15:07:28 -0700 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <63386a3d1002161133k501e51f4xf4e94a307cb4fcf5-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> On Tue, Feb 16, 2010 at 12:33 PM, Linus Walleij <linus.ml.walleij-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > 2010/2/15 jassi brar <jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>: > >> I don't think adding SPI_SLAVE support is just a matter of providing >> additional callbacks and structures, as is pointed out in this thread.... >> http://www.mail-archive.com/spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org/msg00368.html > > You mean that the responsiveness / control of latencies is the other thing > that's needed? Yep so it is. But getting the infrastructure in place doesn't > hurt because this is something many people (including self) need and Ken > over at Intel is the only one actually doing something about it. No, the model needs to be in place first. That means describing the model for spi_slave transfers. Does the driver need to turn around and respond mid-transfer? Does there need to be latency controls? How are protocol drivers interfaced with spi slave controllers (1 to 1, or 1 to many, how is the protocol selected)? I appreciate the work Ken is doing, but the patches posted so far abuse the spi_master model in a way I'm not willing to merge. I think spi_slave is a different enough thing that it warrants an entirely different core infrastructure (but I do reserve the right to have my mind changed). > Getting SPI slaves to actually work by spawning their worker threads as > realtime under that patchset is of course a larger issue. One does not > exclude the other tho. Your right, the realtime issues are separate, but I still need to see how spi_slave devices are intended to work, and what the strengths/limitations of the model are. g. ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev
next prev parent reply other threads:[~2010-02-16 22:07 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-12-18 21:06 Ken Mills 2010-01-19 15:59 ` Grant Likely [not found] ` <fa686aa41001190759j1d916f87o309efe37b3e96bf4-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2010-02-14 23:20 ` Linus Walleij [not found] ` <63386a3d1002141520p7cf33256vd8d6f7c23f61b0fe-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2010-02-15 1:37 ` jassi brar [not found] ` <1b68c6791002141737l6211c88dy79c762a3761cc93c-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2010-02-16 19:33 ` Linus Walleij [not found] ` <63386a3d1002161133k501e51f4xf4e94a307cb4fcf5-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2010-02-16 20:48 ` Ned Forrester [not found] ` <4B7B048C.8080205-/d+BM93fTQY@public.gmane.org> 2010-02-17 3:19 ` Grant Likely 2010-02-16 22:07 ` Grant Likely [this message] 2010-02-17 1:43 ` jassi brar 2010-02-16 22:01 ` Grant Likely
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