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