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From: Philipp Zabel <p.zabel@pengutronix.de>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Grant Likely <grant.likely@secretlab.ca>,
	Rob Herring <rob.herring@calxeda.com>,
	Shawn Guo <shawn.guo@linaro.org>,
	Richard Zhao <richard.zhao@freescale.com>,
	Huang Shijie <shijie8@gmail.com>,
	Dong Aisheng <dong.aisheng@linaro.org>,
	Matt Porter <mporter@ti.com>,
	kernel@pengutronix.de, devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH v5 3/4] misc: sram: Add optional clock
Date: Mon, 29 Oct 2012 13:20:57 +0100	[thread overview]
Message-ID: <1351513257.5872.104.camel@pizza.hi.pengutronix.de> (raw)
In-Reply-To: <CAP=VYLpwahaxVssP1bXmp+ttM_eArF9B2DX1auiOmterdHHUGw@mail.gmail.com>

Am Freitag, den 26.10.2012, 12:17 -0400 schrieb Paul Gortmaker:
> On Thu, Oct 18, 2012 at 10:27 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> > On some platforms the SRAM needs a clock to be enabled explicitly.
> >
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.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.

Right.
How about I set sram->clk = NULL in sram_probe if devm_clk_get returns
an error value?

> 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.

Calling devm_clk_get on the same clock twice seems a bit weird.
I expect that eventually someone will want to disable clocks during
suspend, so I'd prefer to keep the clk pointer around.

regards
Philipp

  reply	other threads:[~2012-10-29 12:20 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-18 14:27 [PATCH v5 0/4] Add generic driver for on-chip SRAM Philipp Zabel
2012-10-18 14:27 ` [PATCH v5 1/4] genalloc: add a global pool list, allow to find pools by phys address Philipp Zabel
2012-10-25 18:56   ` Greg Kroah-Hartman
     [not found]   ` <1350570453-24546-2-git-send-email-p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2012-10-26 19:46     ` Paul Gortmaker
2012-11-15 13:25       ` Philipp Zabel
     [not found]         ` <1352985943.2399.198.camel-/rZezPiN1rtR6QfukMTsflXZhhPuCNm+@public.gmane.org>
2012-11-16  1:50           ` Paul Gortmaker
2012-10-18 14:27 ` [PATCH v5 2/4] misc: Generic on-chip SRAM allocation driver Philipp Zabel
2012-10-26 16:07   ` Paul Gortmaker
2012-10-29 12:20     ` Philipp Zabel
     [not found]       ` <1351513256.5872.103.camel-/rZezPiN1rtR6QfukMTsflXZhhPuCNm+@public.gmane.org>
2012-11-06 18:43         ` Paul Gortmaker
2012-10-18 14:27 ` [PATCH v5 3/4] misc: sram: Add optional clock Philipp Zabel
2012-10-26 15:18   ` Paul Gortmaker
2012-10-29 12:20     ` Philipp Zabel
2012-10-26 16:17   ` Paul Gortmaker
2012-10-29 12:20     ` Philipp Zabel [this message]
     [not found]       ` <1351513257.5872.104.camel-/rZezPiN1rtR6QfukMTsflXZhhPuCNm+@public.gmane.org>
2012-11-06 18:28         ` Paul Gortmaker
2012-10-18 14:27 ` [PATCH v5 4/4] misc: sram: add support for configurable allocation order Philipp Zabel
2012-11-14 19:15   ` Grant Likely
2012-11-15 13:11     ` Philipp Zabel
2012-11-15 16:52       ` Grant Likely
     [not found]       ` <1352985095.2399.184.camel-/rZezPiN1rtR6QfukMTsflXZhhPuCNm+@public.gmane.org>
2012-11-16 14:09         ` Matt Porter
2012-11-16 14:11           ` Grant Likely
2012-11-16 15:58           ` Philipp Zabel

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