On Tue, Sep 24, 2019 at 09:46:20AM +0000, David Laight wrote:
> From: Anson Huang
> > Sent: 24 September 2019 10:00
> > Add helper variable dev = &pdev->dev to simply the code.
> > 
> > Signed-off-by: Anson Huang <[email protected]>
> > ---
> >  drivers/pwm/pwm-imx27.c | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
> > index 434a351..3afee29 100644
> > --- a/drivers/pwm/pwm-imx27.c
> > +++ b/drivers/pwm/pwm-imx27.c
> > @@ -290,27 +290,28 @@ MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids);
> > 
> >  static int pwm_imx27_probe(struct platform_device *pdev)
> >  {
> > +   struct device *dev = &pdev->dev;
> >     struct pwm_imx27_chip *imx;
> > 
> > -   imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
> > +   imx = devm_kzalloc(dev, sizeof(*imx), GFP_KERNEL);
> >     if (imx == NULL)
> >             return -ENOMEM;
> > 
> >     platform_set_drvdata(pdev, imx);
> > 
> > -   imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
> > +   imx->clk_ipg = devm_clk_get(dev, "ipg");
> >     if (IS_ERR(imx->clk_ipg)) {
> > -           dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
> > +           dev_err(dev, "getting ipg clock failed with %ld\n",
> >                             PTR_ERR(imx->clk_ipg));
> >             return PTR_ERR(imx->clk_ipg);
> >     }
> > 
> > -   imx->clk_per = devm_clk_get(&pdev->dev, "per");
> > +   imx->clk_per = devm_clk_get(dev, "per");
> >     if (IS_ERR(imx->clk_per)) {
> >             int ret = PTR_ERR(imx->clk_per);
> > 
> >             if (ret != -EPROBE_DEFER)
> > -                   dev_err(&pdev->dev,
> > +                   dev_err(dev,
> >                             "failed to get peripheral clock: %d\n",
> >                             ret);
> 
> Hopefully the compiler will optimise this back otherwise you've added another
> local variable which may cause spilling to stack.
> For a setup function it probably doesn't matter, but in general it might
> have a small negative performance impact.
> 
> In any case this doesn't shorten any lines enough to remove line-wrap
> and using &pdev->dev is really one less variable to mentally track
> when reading the code.
> 
>       David

I agree. A positive diffstat is often a good indication that it's not
worth it. Don't get me wrong, I think there are cases where an extra
local variable can be worth it, but this isn't one of them, so it's
really just unnecessary churn.

Thierry

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