Re: [PATCH 4/9] pinctrl: samsung: Use generic of_device_get_match_data helper

Bartlomiej Zolnierkiewicz
2016-12-27T10:28:19Z

Hi,

On Monday, December 26, 2016 11:41:42 AM Krzysztof Kozlowski wrote:
> On Mon, Dec 26, 2016 at 02:44:26PM +0900, Tomasz Figa wrote:
> > 2016-12-25 21:56 GMT+09:00 Krzysztof Kozlowski <krzk@kernel.org>:
> > > On Fri, Dec 23, 2016 at 01:24:44PM +0100, Marek Szyprowski wrote:
> > >> Replace custom code with generic helper.
> > >>
> > >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > >> ---
> > >> drivers/pinctrl/samsung/pinctrl-samsung.c | 9 ++++-----
> > >> 1 file changed, 4 insertions(+), 5 deletions(-)
> > >>
> > >> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.c b/drivers/pinctrl/samsung/pinctrl-samsung.c
> > >> index 4d9262051ff1..a6c2ea74e0f3 100644
> > >> --- a/drivers/pinctrl/samsung/pinctrl-samsung.c
> > >> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.c
> > >> @@ -27,6 +27,7 @@
> > >> #include <linux/err.h>
> > >> #include <linux/gpio.h>
> > >> #include <linux/irqdomain.h>
> > >> +#include <linux/of_device.h>
> > >> #include <linux/spinlock.h>
> > >> #include <linux/syscore_ops.h>
> > >>
> > >> @@ -967,15 +968,13 @@ static int samsung_gpiolib_unregister(struct platform_device *pdev,
> > >> return 0;
> > >> }
> > >>
> > >> -static const struct of_device_id samsung_pinctrl_dt_match[];
> > >> -
> > >> /* retrieve the soc specific data */
> > >> static const struct samsung_pin_ctrl *
> > >> samsung_pinctrl_get_soc_data(struct samsung_pinctrl_drv_data *d,
> > >> struct platform_device *pdev)
> > >> {
> > >> int id;
> > >> - const struct of_device_id *match;
> > >> + const struct samsung_pin_ctrl *match_data;
> > >> struct device_node *node = pdev->dev.of_node;
> > >> struct device_node *np;
> > >> const struct samsung_pin_bank_data *bdata;
> > >> @@ -990,8 +989,8 @@ static int samsung_gpiolib_unregister(struct platform_device *pdev,
> > >> dev_err(&pdev->dev, "failed to get alias id\n");
> > >> return ERR_PTR(-ENOENT);
> > >> }
> > >> - match = of_match_node(samsung_pinctrl_dt_match, node);
> > >> - ctrl = (struct samsung_pin_ctrl *)match->data + id;
> > >> + match_data = of_device_get_match_data(&pdev->dev);
> > >> + ctrl = match_data + id;
> > >
> > > Either you need a check for match_data != NULL or just remove match_data
> > > and:
> > > ctrl = of_device_get_match_data();
> > > ctrl += id;
> > >
> > > Actually match_data can be removed even with the check for non-NULL...
> >
> > I don't think this function can ever return NULL if the match array
> > contains a non-NULL value for each compatible string and the driver
> > can be probed only by DT.
>
> Practically it cannot (or it should not) but defensive coding is a good
> practice...

Defensive coding is not a good practice, please don't recommend it.

It usually just obfuscates code and hides underlying issue.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics