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Date:   Thu, 3 Jan 2019 12:37:20 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>
Cc:     "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
        Ben Whitten <ben.whitten@gmail.com>,
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        Maxime Ripard <maxime.ripard@bootlin.com>,
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        Stephen Boyd <sboyd@codeaurora.org>,
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        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 lora-next 5/5] net: lora: sx125x sx1301: allow radio
 to register as a clk provider
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On Wed, Jan 02, 2019 at 01:44:40AM +0100, Andreas F=E4rber wrote:

> So, the third invocation of sun6i_transfer_one() calling clk_get_rate()
> hangs at the prepare_lock instead of reference-counting, because it runs
> from a separate kthread, unlike the two previous calls?

If there's any contestation for the bus we push all the I/O through a
separate thread to maintain ordering and improve performance.

> I did not find any *regmap_init_spi() based example in drivers/clk/, and
> all other "spi" mentions in drivers/clk/ appeared to be clock names.
> The closest was devm_regmap_init_i2c() based clk-cdce706.c, which uses
> the prepare/unprepare ops, as suggested by Mark, and does
> regmap_update_bits() from there.

You'll find a bunch of the MFDs have SPI options as well.

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