linux-kernel - Re: [PATCH v8 2/2] spi: loongson: add bus driver for the loongson spi controller

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Message-ID: <c24f8a28-23d4-46e3-8ff2-4b6f4e39b493@sirena.org.uk>
Date:   Wed, 19 Apr 2023 13:36:07 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Yinbo Zhu <zhuyinbo@...ngson.cn>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jianmin Lv <lvjianmin@...ngson.cn>,
        wanghongliang@...ngson.cn, Liu Peibao <liupeibao@...ngson.cn>,
        loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH v8 2/2] spi: loongson: add bus driver for the loongson
 spi controller

On Wed, Apr 19, 2023 at 02:22:02PM +0800, Yinbo Zhu wrote:

> +       clk = devm_clk_get(dev, NULL);
> +       if (!IS_ERR(clk))
> +               spi->clk_rate = clk_get_rate(clk);

I notice we never actually enable this clock.  I guess it's some system
clock which is needed for basic system functionality which is always on
and we just need the rate but it looks a bit off.

> +static int __maybe_unused loongson_spi_suspend(struct device *dev)
> +{
> +	struct loongson_spi *loongson_spi;
> +	struct spi_master *master;
> +
> +	master = dev_get_drvdata(dev);
> +	loongson_spi = spi_master_get_devdata(master);
> +
> +	loongson_spi->spcr = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
> +	loongson_spi->sper = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPER_REG);
> +	loongson_spi->spsr = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPSR_REG);
> +	loongson_spi->para = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_PARA_REG);
> +	loongson_spi->sfcs = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SFCS_REG);
> +	loongson_spi->timi = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_TIMI_REG);
> +
> +	spi_master_suspend(master);

This saves the register state before suspending at the SPI level but
that means that if there were any transfers in progress then the
register state might be changed by the active transfers after we've
saved the state, meaning we might restore a state for an active
transfer.  The spi_master_suspend() should go first, then save the
register state.  The resume is OK, it's just the suspend.

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