Date: Wed, 29 Jul 2020 13:35:27 -0600 From: Ian Lepore <ian@freebsd.org> To: kamalp@acm.org, freebsd-arm@freebsd.org Subject: Re: mutexes Message-ID: <c5395d0ee44d77345aeb74033874df165e167977.camel@freebsd.org> In-Reply-To: <CAK=yUGKiLx9Xh-LSGeHLbJzUPiALkbs9AdajDCVN--iMeAykBw@mail.gmail.com> References: <CAK=yUGKiLx9Xh-LSGeHLbJzUPiALkbs9AdajDCVN--iMeAykBw@mail.gmail.com>
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On Thu, 2020-07-30 at 00:56 +0530, Kamal R. Prasad wrote: > hello, > > i have 2 instances of an spi controller (pl022) on my setup. can someone > tell me :- > 1. is there any danger if we interleave spi io transfers between these 2 > controllers i.e spi transfer starts on controller 0 and before it can > finish, controller 1 starts spi transfer. the 2 controllers have different > spi slave devices. > 2. assuming there is an issue with that, how to setup a mutex in the code > path so that it is common to both instances of pl022 driver? > I have never encountered a system with multiple instances of a SPI controller where they interfered with each other in any way. Unless there is documentation to the contrary for your hardware, I think it is safe to assume that you can have two unrelated SPI transfers happening on the two different instances without any problems. -- Ian
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