From: Mark Brown <broonie@kernel.org>
To: kernel@martin.sperl.org
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
linux-spi <linux-spi@vger.kernel.org>,
Eric Anholt <eric@anholt.net>, Lukas Wunner <lukas@wunner.de>,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/5] spi: core: allow defining time that cs is deasserted as a multiple of SCK
Date: Tue, 26 Feb 2019 11:37:20 +0000 [thread overview]
Message-ID: <20190226113720.GB7082@sirena.org.uk> (raw)
In-Reply-To: <0CA42E9E-3297-41EC-8E90-FAE937E892DE@martin.sperl.org>
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On Sun, Feb 24, 2019 at 12:03:33PM +0100, kernel@martin.sperl.org wrote:
> Some devices - like the mcp2517fd - have for example an internal PLL
> based on an external clock. So during setup you have to use speed_hz
> of <clock_hz> / 2 (or 4MHz at most) and only when PLL is in sync we
> may be using speed_hz from the dt (or less if a module parameter is
> used to limit ourselves further)
> So the initial setup would not be able to help here - and every
> bus controller would now be required to implement setup.
> It also means open coding the calculations in each driver that
> needs something like this.
> Thus it is - imo - in the right location to support it in spi core.
I agree, this feature makes sense to me.
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next prev parent reply other threads:[~2019-02-26 11:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-23 8:49 [PATCH 0/5] allow to define cs deassert times in us, ns and SCK-len kernel
2019-02-23 8:49 ` kernel
2019-02-23 8:49 ` [PATCH 2/5] spi: core: allow reporting the effectivly used speed_hz for a transfer kernel
2019-02-23 8:49 ` kernel
2019-02-23 8:49 ` [PATCH 3/5] spi: core: allow defining time that cs is deasserted as a multiple of SCK kernel
2019-02-23 8:49 ` kernel
[not found] ` <20190223124010.y7lsncknnxoblvgz@wunner.de>
[not found] ` <20190223124010.y7lsncknnxoblvgz-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
2019-02-23 13:15 ` kernel-TqfNSX0MhmxHKSADF0wUEw
2019-02-23 13:15 ` kernel
[not found] ` <20190224103913.bjw7g6ievr75iawz@wunner.de>
[not found] ` <20190224103913.bjw7g6ievr75iawz-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
2019-02-24 11:03 ` kernel-TqfNSX0MhmxHKSADF0wUEw
2019-02-24 11:03 ` kernel
2019-02-26 11:37 ` Mark Brown [this message]
2019-05-07 10:07 ` kernel
2019-05-07 10:07 ` kernel
[not found] ` <20190223084952.14758-1-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2019-02-23 8:49 ` [PATCH 1/5] spi: core: allow defining time that cs is deasserted kernel-TqfNSX0MhmxHKSADF0wUEw
2019-02-23 8:49 ` kernel
[not found] ` <20190223084952.14758-2-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
2019-05-08 9:34 ` Applied "spi: core: allow defining time that cs is deasserted" to the spi tree Mark Brown
2019-05-08 9:34 ` Mark Brown
2019-02-23 8:49 ` [PATCH 4/5] spi: bcm2835: support effective_speed_hz kernel-TqfNSX0MhmxHKSADF0wUEw
2019-02-23 8:49 ` kernel
2019-05-13 15:14 ` Mark Brown
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