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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Dirk Behme <dirk.behme@de.bosch.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Julien Grall <julien.grall@arm.com>,
	xen-devel@lists.xenproject.org,
	linux-clk <linux-clk@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4] xen/arm: Add a clock property
Date: Wed, 20 Jul 2016 11:43:03 +0200	[thread overview]
Message-ID: <CAMuHMdU9yP2SMYa5ssrQSu1vwSN2gM4mD-EVYSGr2Pqf=jmCgw__21497.3209346228$1469007860$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <1468309605-19522-1-git-send-email-dirk.behme@de.bosch.com>

Hi Dirk,

On Tue, Jul 12, 2016 at 9:46 AM, Dirk Behme <dirk.behme@de.bosch.com> wrote:
> Clocks described by this property are reserved for use by Xen, and the OS
> must not alter their state any way, such as disabling or gating a clock,
> or modifying its rate. Ensuring this may impose constraints on parent
> clocks or other resources used by the clock tree.
>
> This property is used to proxy clocks for devices Xen has taken ownership
> of, such as UARTs, for which the associated clock controller(s) remain
> under the control of Dom0.

I'm not familiar with using XEN at all, but I'm a bit puzzled...

Can't you just add a clocks property to the (virtual) serial device node in DT?
Then the (virtual) serial device driver can get and enable the clock?

Alternatively, you can add a (virtual) clock controller, and power-domains
and clock properties to all affected devices (I assume there can be others,
besides virtual UARTs?), and let it be handled by Runtime PM, without the
(virtual) device drivers having to care about clocks at all.

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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  parent reply	other threads:[~2016-07-20  9:43 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1468309605-19522-1-git-send-email-dirk.behme@de.bosch.com>
2016-07-12 22:26 ` [PATCH v4] xen/arm: Add a clock property Michael Turquette
     [not found] ` <146836236759.73491.11707389619985827497@resonance>
2016-07-13  8:35   ` Dirk Behme
     [not found]   ` <c320f820-8749-f4a4-435e-ddd9379655b5@de.bosch.com>
2016-07-13 18:43     ` Stefano Stabellini
     [not found]     ` <alpine.DEB.2.10.1607131941200.26575@sstabellini-ThinkPad-X260>
2016-07-13 18:56       ` Dirk Behme
     [not found]       ` <57868EDE.6060406@gmail.com>
2016-07-13 21:03         ` Michael Turquette
     [not found]         ` <146844380895.73491.4867379517577413421@resonance>
2016-07-14  6:31           ` Dirk Behme
     [not found]           ` <7df784ab-d0c0-939b-393e-214535c4b191@de.bosch.com>
2016-07-14 10:14             ` Julien Grall
     [not found]             ` <57876612.3030407@arm.com>
2016-07-14 10:32               ` Dirk Behme
2016-07-14 10:38             ` Stefano Stabellini
     [not found]             ` <alpine.DEB.2.10.1607141132000.26575@sstabellini-ThinkPad-X260>
2016-07-14 10:49               ` Dirk Behme
     [not found]               ` <86951b96-0a3e-79b1-1a2f-88dfeba9b76b@de.bosch.com>
2016-07-14 15:55                 ` Stefano Stabellini
     [not found]                 ` <alpine.DEB.2.10.1607141647350.22290@sstabellini-ThinkPad-X260>
2016-07-14 16:30                   ` Dirk Behme
     [not found]                   ` <5787BE0B.8060504@gmail.com>
2016-07-14 17:14                     ` Julien Grall
     [not found]                     ` <5787C88A.8030103@arm.com>
2016-07-15  7:53                       ` Dirk Behme
2016-07-22  0:07               ` Michael Turquette
     [not found]               ` <146914607316.8780.7961396342647226841@resonance>
2016-07-22  1:16                 ` Stefano Stabellini
     [not found]                 ` <alpine.DEB.2.10.1607211804000.6667@sstabellini-ThinkPad-X260>
2016-07-27  5:05                   ` Dirk Behme
     [not found]                   ` <dbd46fe5-6f53-d11e-6363-a2c9905d6c8e@gmail.com>
2016-07-28 11:17                     ` Julien Grall
     [not found]                     ` <1a486d3b-0dda-d545-ca6a-031a8bf932e9@arm.com>
2016-07-28 14:35                       ` Dirk Behme
2016-07-14 10:25           ` Stefano Stabellini
2016-07-13 18:35 ` Stefano Stabellini
     [not found] ` <alpine.DEB.2.10.1607131932530.26575@sstabellini-ThinkPad-X260>
2016-07-13 18:47   ` Dirk Behme
     [not found]   ` <57868CB4.1090504@gmail.com>
2016-07-13 19:07     ` Stefano Stabellini
     [not found]     ` <alpine.DEB.2.10.1607132002000.26575@sstabellini-ThinkPad-X260>
2016-07-14  6:11       ` Dirk Behme
     [not found]       ` <094be367-ff91-aec7-cbd6-cfb8dc711c54@de.bosch.com>
2016-07-14 10:28         ` Stefano Stabellini
2016-07-20  9:43 ` Geert Uytterhoeven [this message]
     [not found] ` <CAMuHMdU9yP2SMYa5ssrQSu1vwSN2gM4mD-EVYSGr2Pqf=jmCgw@mail.gmail.com>
2016-07-20 11:01   ` Julien Grall
     [not found]   ` <cc28ef7e-dce3-fe5f-ab80-b662244bcbd0@arm.com>
2016-07-20 11:49     ` Geert Uytterhoeven
     [not found]     ` <CAMuHMdWeJjcuBHjnjppc5Ys5Ew8VssXzg=dLpLPCOQaBnUo_7Q@mail.gmail.com>
2016-07-20 12:10       ` Julien Grall
     [not found]       ` <04d9dbfb-196d-a775-7fbb-526aba8085f4@arm.com>
2016-07-20 12:46         ` Geert Uytterhoeven
     [not found]         ` <CAMuHMdWdqdT4jnae8h9tDDzzh8ZAbJJwiMW-scPBNVwmjYSiWQ@mail.gmail.com>
2016-07-20 12:53           ` Dirk Behme
2016-07-20 13:21           ` Julien Grall
     [not found]           ` <457c61fd-4a64-b050-cd87-845b7e22ec39@arm.com>
2016-07-22  0:14             ` Michael Turquette
2016-07-12  7:46 Dirk Behme

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