linux-kernel - Re: [PATCH 5/9] spi: amd: Refactor amd_spi_busy_wait to use readl_poll

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Message-ID: <20210824164650.GI4393@sirena.org.uk>
Date:   Tue, 24 Aug 2021 17:46:50 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Lucas Tanure <tanureal@...nsource.cirrus.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Sanjay R Mehta <sanju.mehta@....com>,
        Nehal Bakulchandra Shah <Nehal-Bakulchandra.shah@....com>,
        linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
        patches@...nsource.cirrus.com
Subject: Re: [PATCH 5/9] spi: amd: Refactor amd_spi_busy_wait to use
 readl_poll_timeout

On Tue, Aug 24, 2021 at 11:40:37AM +0100, Lucas Tanure wrote:

> -	spi_busy = (ioread32((u8 __iomem *)amd_spi->io_remap_addr +
> -		    AMD_SPI_CTRL0_REG) & AMD_SPI_BUSY) == AMD_SPI_BUSY;

This does ioread32() while readl_poll_timeout() does a readl().  These
are almost but not quite equivalent and the differences apply to PCI
devices like this one, see device-io.rst.

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