linux-kernel - Re: [PATCH v2 7/9] spi: spi-s3c64xx: Ensure cur

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Message-ID: <20200822124325.GF20423@kozik-lap>
Date:   Sat, 22 Aug 2020 14:43:25 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Łukasz Stelmach <l.stelmach@...sung.com>
Cc:     Kukjin Kim <kgene@...nel.org>, Andi Shyti <andi@...zian.org>,
        Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        m.szyprowski@...sung.com, b.zolnierkie@...sung.com,
        Tomasz Figa <tfiga@...omium.org>
Subject: Re: [PATCH v2 7/9] spi: spi-s3c64xx: Ensure cur_speed holds actual
 clock value

On Fri, Aug 21, 2020 at 06:13:59PM +0200, Łukasz Stelmach wrote:
> cur_speed is used to calculate transfer timeout and needs to be
> set to the actual value of (half) the clock speed for precise
> calculations.

If you need this only for timeout calculation just divide it in
s3c64xx_wait_for_dma(). Otherwise why only if (cmu) case is updated?

You are also affecting here not only timeout but
s3c64xx_enable_datapath() which is not mentioned in commit log. In other
words, this looks wrong.

Best regards,
Krzysztof

> 
> Cc: Tomasz Figa <tfiga@...omium.org>
> Signed-off-by: Łukasz Stelmach <l.stelmach@...sung.com>
> ---
>  drivers/spi/spi-s3c64xx.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index 02de734b8ab1..89c162efe355 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -626,6 +626,7 @@ static int s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
>  		ret = clk_set_rate(sdd->src_clk, sdd->cur_speed * 2);
>  		if (ret)
>  			return ret;
> +		sdd->cur_speed = clk_get_rate(sdd->src_clk) / 2;
>  	} else {
>  		/* Configure Clock */
>  		val = readl(regs + S3C64XX_SPI_CLK_CFG);
> -- 
> 2.26.2
>