linux-kernel - Re: [PATCH v5 3/4] misc: sram: Add optional clock

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Message-ID: <CAP=VYLpwahaxVssP1bXmp+ttM_eArF9B2DX1auiOmterdHHUGw@mail.gmail.com>
Date:	Fri, 26 Oct 2012 12:17:15 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	Shawn Guo <shawn.guo@...aro.org>,
	Richard Zhao <richard.zhao@...escale.com>,
	Huang Shijie <shijie8@...il.com>,
	Dong Aisheng <dong.aisheng@...aro.org>,
	Matt Porter <mporter@...com>, kernel@...gutronix.de,
	devicetree-discuss@...ts.ozlabs.org
Subject: Re: [PATCH v5 3/4] misc: sram: Add optional clock

On Thu, Oct 18, 2012 at 10:27 AM, Philipp Zabel <p.zabel@...gutronix.de> wrote:
> On some platforms the SRAM needs a clock to be enabled explicitly.
>
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
>  drivers/misc/sram.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index 7a363f2..0cc2e75 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -21,6 +21,8 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/init.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
>  #include <linux/io.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
> @@ -29,6 +31,7 @@
>
>  struct sram_dev {
>         struct gen_pool *pool;
> +       struct clk *clk;
>  };

I see another field gets added to the struct here.  (yet another
reason to have it folded into the original)   But you still
really don't need to create a sram_dev for this, because...

>
>  static int __devinit sram_probe(struct platform_device *pdev)
> @@ -53,6 +56,10 @@ static int __devinit sram_probe(struct platform_device *pdev)
>         if (!sram)
>                 return -ENOMEM;
>
> +       sram->clk = devm_clk_get(&pdev->dev, NULL);
> +       if (!IS_ERR(sram->clk))
> +               clk_prepare_enable(sram->clk);
> +
>         sram->pool = gen_pool_create(PAGE_SHIFT, -1);
>         if (!sram->pool)
>                 return -ENOMEM;
> @@ -80,6 +87,9 @@ static int __devexit sram_remove(struct platform_device *pdev)
>
>         gen_pool_destroy(sram->pool);
>
> +       if (!IS_ERR(sram->clk))
> +               clk_disable_unprepare(sram->clk);
> +

...here, this looks confusing with the use of IS_ERR on
an entity that was not recently assigned to.  Instead, just
put a "struct clk *clk;" on the stack and do the

   clk = devm_clk_get(&pdev->dev, NULL);

in both the init and the teardown.  Then the code will be
more readable.

P.
--

>         return 0;
>  }
>
> --
> 1.7.10.4
>
> --
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