From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Samuel Holland <samuel@sholland.org>
Cc: Chen-Yu Tsai <wens@csie.org>,
Jassi Brar <jassisinghbrar@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH 3/3] mailbox: sunxi-msgbox: Add a new mailbox driver
Date: Wed, 28 Feb 2018 09:32:14 +0100 [thread overview]
Message-ID: <20180228083214.h4oi2kmjjqmoyfhn@flea> (raw)
In-Reply-To: <20180228022714.30068-4-samuel@sholland.org>
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On Tue, Feb 27, 2018 at 08:27:14PM -0600, Samuel Holland wrote:
> + /*
> + * The failure path should not disable the clock or assert the reset,
> + * because the PSCI implementation in firmware relies on this device
> + * being functional. Claiming the clock in this driver is required to
> + * prevent Linux from turning it off.
> + */
> + ret = clk_prepare_enable(clk);
> + if (ret) {
> + dev_err(dev, "Failed to enable bus clock: %d\n", ret);
> + return ret;
> + }
You don't need it to be always on though. You only need it to be
enabled when you access the registers (on both sides I guess?). So you
could very well enable the clock in your registers accessors in Linux,
and do the same in the ARISC firmware. That should work.
Maxime
--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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From: maxime.ripard@bootlin.com (Maxime Ripard)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/3] mailbox: sunxi-msgbox: Add a new mailbox driver
Date: Wed, 28 Feb 2018 09:32:14 +0100 [thread overview]
Message-ID: <20180228083214.h4oi2kmjjqmoyfhn@flea> (raw)
In-Reply-To: <20180228022714.30068-4-samuel@sholland.org>
On Tue, Feb 27, 2018 at 08:27:14PM -0600, Samuel Holland wrote:
> + /*
> + * The failure path should not disable the clock or assert the reset,
> + * because the PSCI implementation in firmware relies on this device
> + * being functional. Claiming the clock in this driver is required to
> + * prevent Linux from turning it off.
> + */
> + ret = clk_prepare_enable(clk);
> + if (ret) {
> + dev_err(dev, "Failed to enable bus clock: %d\n", ret);
> + return ret;
> + }
You don't need it to be always on though. You only need it to be
enabled when you access the registers (on both sides I guess?). So you
could very well enable the clock in your registers accessors in Linux,
and do the same in the ARISC firmware. That should work.
Maxime
--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2018-02-28 8:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-28 2:27 [PATCH 0/3] Allwinner sunxi message box support Samuel Holland
2018-02-28 2:27 ` Samuel Holland
2018-02-28 2:27 ` [PATCH 1/3] dt-bindings: Add a binding for the sunxi message box Samuel Holland
2018-02-28 2:27 ` Samuel Holland
2018-02-28 8:28 ` Maxime Ripard
2018-02-28 8:28 ` Maxime Ripard
2018-02-28 17:17 ` Andre Przywara
2018-02-28 17:17 ` Andre Przywara
2018-03-01 10:03 ` Maxime Ripard
2018-03-01 10:03 ` Maxime Ripard
2018-02-28 17:52 ` Samuel Holland
2018-02-28 17:52 ` Samuel Holland
2018-02-28 2:27 ` [PATCH 2/3] mailbox: Avoid NULL dereference in mbox_chan_received_data Samuel Holland
2018-02-28 2:27 ` Samuel Holland
2018-02-28 17:17 ` Andre Przywara
2018-02-28 17:17 ` Andre Przywara
2018-03-01 13:32 ` Jassi Brar
2018-03-01 13:32 ` Jassi Brar
2018-02-28 2:27 ` [PATCH 3/3] mailbox: sunxi-msgbox: Add a new mailbox driver Samuel Holland
2018-02-28 2:27 ` Samuel Holland
2018-02-28 8:32 ` Maxime Ripard [this message]
2018-02-28 8:32 ` Maxime Ripard
2018-02-28 17:19 ` Samuel Holland
2018-02-28 17:19 ` Samuel Holland
2018-03-01 10:32 ` Maxime Ripard
2018-03-01 10:32 ` Maxime Ripard
2018-03-01 11:32 ` Andre Przywara
2018-03-01 11:32 ` Andre Przywara
2018-03-01 11:51 ` Maxime Ripard
2018-03-01 11:51 ` Maxime Ripard
2018-02-28 9:16 ` Jassi Brar
2018-02-28 9:16 ` Jassi Brar
2018-02-28 17:51 ` Samuel Holland
2018-02-28 17:51 ` Samuel Holland
2018-02-28 18:14 ` Jassi Brar
2018-02-28 18:14 ` Jassi Brar
2018-02-28 18:14 ` Jassi Brar
2018-02-28 18:56 ` Samuel Holland
2018-02-28 18:56 ` Samuel Holland
2018-02-28 18:56 ` Samuel Holland
2018-03-01 5:22 ` Jassi Brar
2018-03-01 5:22 ` Jassi Brar
2018-03-01 5:22 ` Jassi Brar
2018-02-28 8:24 ` [PATCH 0/3] Allwinner sunxi message box support Maxime Ripard
2018-02-28 8:24 ` Maxime Ripard
2018-02-28 17:18 ` Samuel Holland
2018-02-28 17:18 ` Samuel Holland
2018-03-01 10:28 ` Maxime Ripard
2018-03-01 10:28 ` Maxime Ripard
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