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Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for hwspinlock_device

From	Lina Iyer <lina.iyer@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for hwspinlock_device
Date	2015-08-14 16:00 +0200
Message-ID	<pXnGx-3Qu-9@gated-at.bofh.it> (permalink)
References	(4 earlier) <pNyDg-2PY-9@gated-at.bofh.it> <pRl4K-51M-7@gated-at.bofh.it> <pWUlc-3IA-27@gated-at.bofh.it> <pX2C7-7ft-31@gated-at.bofh.it> <pXkSm-8h8-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Aug 14 2015 at 04:52 -0600, Ohad Ben-Cohen wrote:
>On Thu, Aug 13, 2015 at 6:25 PM, Andy Gross <agross@codeaurora.org> wrote:
>> The issue in hardwiring this into the driver itself means forfeiting
>> extensibility.  So on one side (w/ raw support), we get the ability to deal with
>> the lock number changing.  On the other side (w/o raw), we'd have to probably
>> tie this to chip compat to figure out which lock is the 'special' if it ever
>> changes.
>
>It sounds like the decision "which lock to use" is a separate problem
>from "can it go raw".
>
Absolutely.

>If the hardware doesn't prohibit raw mode, then every lock can be used
>in raw mode. So you just have to pick one and make sure both sides
>know which lock you use --- which is a classic multi-processor
>synchronization issue.
>
>> It's arbitrary right now.  The remote processor selected a number, not the
>> processor running Linux.
>
>Is the number hardcoded right now? and you're using
>hwspin_lock_request_specific on the Linux side to acquire the lock?
>
Yes, the number is hardcoded in the SPM power controller driver. It
explicitly requests Lock #7

-- Lina
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Thread

Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for hwspinlock_device Ohad Ben-Cohen <ohad@wizery.com> - 2015-08-13 08:40 +0200
  Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for  hwspinlock_device Andy Gross <agross@codeaurora.org> - 2015-08-13 17:30 +0200
    Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for hwspinlock_device Ohad Ben-Cohen <ohad@wizery.com> - 2015-08-14 13:00 +0200
      Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for  hwspinlock_device Lina Iyer <lina.iyer@linaro.org> - 2015-08-14 16:00 +0200
  Re: [PATCH RFC v2 0/2] hwspinlock: Introduce raw capability for  hwspinlock_device Lina Iyer <lina.iyer@linaro.org> - 2015-08-14 17:30 +0200

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