linux-kernel - Re: [PATCH v1] spi: dw: Enable Autosuspend delay for SPI DesignWare

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Date:   Sun, 5 Sep 2021 18:19:19 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     mahesh.r.vaidya@...el.com
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        broonie@...nel.org, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, mgross@...ux.intel.com,
        kris.pan@...el.com, furong.zhou@...el.com,
        mallikarjunappa.sangannavar@...el.com,
        lakshmi.bai.raja.subramanian@...el.com
Subject: Re: [PATCH v1] spi: dw: Enable Autosuspend delay for SPI DesignWare

On Sat, Sep 04, 2021 at 05:27:58AM +0800, mahesh.r.vaidya@...el.com wrote:
> From: Mahesh R Vaidya <mahesh.r.vaidya@...el.com>
> 
> Enable and set Autosuspend delay for SPI DesignWare driver.
> The number 1000 ms for the autosuspend delay was picked a bit
> arbitrarily, so if someone has measurements showing a better
> value we could easily change this.
> 
> Signed-off-by: Mahesh R Vaidya <mahesh.r.vaidya@...el.com>
> ---
>  drivers/spi/spi-dw-mmio.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index 3379720cfcb8..8b588ce9c16b 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -33,6 +33,8 @@ struct dw_spi_mmio {
>  	struct reset_control *rstc;
>  };
> 
> +#define SPI_DW_DEFAULT_AUTOSUSP_VAL		1000
> +
>  #define MSCC_CPU_SYSTEM_CTRL_GENERAL_CTRL	0x24
>  #define OCELOT_IF_SI_OWNER_OFFSET		4
>  #define JAGUAR2_IF_SI_OWNER_OFFSET		6
> @@ -309,6 +311,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>  			goto out;
>  	}
> 

> +	/* Set initial autosuspend default delay value and enable */
> +	pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_DW_DEFAULT_AUTOSUSP_VAL);
> +	pm_runtime_use_autosuspend(&pdev->dev);
> +	pm_runtime_set_active(&pdev->dev);

Seems reasonable, but doesn't it need to be reverted in the remove
callback? Like it's done in the spi-imx.c driver for instance by
calling the pm_runtime_dont_use_autosuspend() method.

>  	pm_runtime_enable(&pdev->dev);
> 
>  	ret = dw_spi_add_host(&pdev->dev, dws);
> @@ -319,6 +325,7 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>  	return 0;
> 
>  out:

> +	pm_runtime_put_noidle(&pdev->dev);

This doesn't seem like related to the subject, thus needs to be
submitted as a separate patch with fixes tag if it fixes some another
problem. Additionally it isn't balanced with the pm_runtime_get*()
method invocation. Am I missing something?

-Sergey

>  	pm_runtime_disable(&pdev->dev);
>  	clk_disable_unprepare(dwsmmio->pclk);
>  out_clk:
> --
> 2.17.1
>