linux-kernel - Re: [PATCH 1/2] spi: dw: add reset control

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Message-ID: <20200521171203.GH4770@sirena.org.uk>
Date:   Thu, 21 May 2020 18:12:03 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        robh+dt@...nel.org, linux-spi@...r.kernel.org,
        Liang Jin J <liang.j.jin@...csson.com>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        fancer.lancer@...il.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>
Subject: Re: [PATCH 1/2] spi: dw: add reset control

On Thu, May 21, 2020 at 12:03:58PM -0500, Dinh Nguyen wrote:
> Add mechanism to get the reset control and deassert it in order to bring
> the IP out of reset.
> 
> Signed-off-by: Liang Jin J <liang.j.jin@...csson.com>
> Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>

Is the From: correct here?

Also adding everyone else who's got patches in flight for this driver
right now.

> ---
>  drivers/spi/spi-dw-mmio.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
> index 384a3ab6dc2d..5c813e15ed89 100644
> --- a/drivers/spi/spi-dw-mmio.c
> +++ b/drivers/spi/spi-dw-mmio.c
> @@ -20,6 +20,7 @@
>  #include <linux/acpi.h>
>  #include <linux/property.h>
>  #include <linux/regmap.h>
> +#include <linux/reset.h>
>  
>  #include "spi-dw.h"
>  
> @@ -30,6 +31,7 @@ struct dw_spi_mmio {
>  	struct clk     *clk;
>  	struct clk     *pclk;
>  	void           *priv;
> +	struct reset_control	*rstc;
>  };
>  
>  #define MSCC_CPU_SYSTEM_CTRL_GENERAL_CTRL	0x24
> @@ -145,6 +147,10 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
>  	if (!dwsmmio)
>  		return -ENOMEM;
>  
> +	dwsmmio->rstc = devm_reset_control_get_exclusive(&pdev->dev, "spi");
> +	if (!IS_ERR(dwsmmio->rstc))
> +		reset_control_deassert(dwsmmio->rstc);
> +
>  	dws = &dwsmmio->dws;
>  
>  	/* Get basic io resource and map it */

Should we also undo the reset in error paths from probe()?  It's not the
end of the world if we don't but...

> @@ -220,6 +226,9 @@ static int dw_spi_mmio_remove(struct platform_device *pdev)
>  	clk_disable_unprepare(dwsmmio->pclk);
>  	clk_disable_unprepare(dwsmmio->clk);
>  
> +	if (dwsmmio->rstc)
> +		reset_control_assert(dwsmmio->rstc);
> +
>  	return 0;
>  }
>  
> -- 
> 2.17.1
> 

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