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Message-ID: <0ee7ab71-5d01-58e2-baf7-4dd41455b377@rock-chips.com>
Date:   Wed, 16 Feb 2022 09:23:58 +0800
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Subject: Re: [PATCH 2/6] spi: rockchip: Preset cs-high and clk polarity in
 setup progress
To:     Mark Brown <broonie@kernel.org>
Cc:     heiko@sntech.de, linux-spi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20220211034344.4130-1-jon.lin@rock-chips.com>
 <20220211034344.4130-2-jon.lin@rock-chips.com>
 <YgZHalrdhhilxROt@sirena.org.uk>
 <4222ce7d-a1e3-1728-fec2-976946b06ba9@rock-chips.com>
 <YgpP9j80OuhkCN8p@sirena.org.uk>
 <e0f0ca0d-40df-cf86-9471-9272bcc171f9@rock-chips.com>
 <YgueWHKur2w55s+0@sirena.org.uk>
From:   Jon Lin <jon.lin@rock-chips.com>
In-Reply-To: <YgueWHKur2w55s+0@sirena.org.uk>
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在 2022/2/15 20:36, Mark Brown 写道:
> On Tue, Feb 15, 2022 at 11:00:54AM +0800, Jon Lin wrote:
>> 在 2022/2/14 20:49, Mark Brown 写道:
> 
>>> As covered in the documentation setup() for one device may run while
>>> another is active, therefore if multiple devices are configured in the
>>> same register you should use a lock to ensure there can't be multiple
>>> writes.  Note that the above appears to not just be setting the mode but
>>> also the chip select so if you've got two SPI_CS_HIGH devices then
>>> they'll both be going in and separately setting cr0.
> 
>> Is the io_mutex in function spi_setup is good enough?
> 
> It's not supposed to be for that but looking at the code quickly I
> *think* setup() is never called with io_mutex held so it might well be
> fine - you should double check though.  If not you'd need to add another
> lock in your driver data.

》setup() is never called with io_mutex held
I think so. and I think the io_mutex is enough for me.