Re: [PATCH] power: reset: vexpress: Use device_get_match_data()

[Sudeep Holla <sudeep.holla@arm.com>]

On Mon, Oct 09, 2023 at 11:07:33PM +0100, Liviu Dudau wrote:
> Hi Rob,
> 
> On Mon, Oct 09, 2023 at 12:29:14PM -0500, Rob Herring wrote:
> > Use preferred device_get_match_data() instead of of_match_device() to
> > get the driver match data. With this, adjust the includes to explicitly
> > include the correct headers.
> > 
> > Signed-off-by: Rob Herring <robh@kernel.org>
> > ---
> >  drivers/power/reset/vexpress-poweroff.c | 11 ++++-------
> >  1 file changed, 4 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/power/reset/vexpress-poweroff.c b/drivers/power/reset/vexpress-poweroff.c
> > index 17064d7b19f6..bb22b2db5907 100644
> > --- a/drivers/power/reset/vexpress-poweroff.c
> > +++ b/drivers/power/reset/vexpress-poweroff.c
> > @@ -7,8 +7,8 @@
> >  #include <linux/delay.h>
> >  #include <linux/notifier.h>
> >  #include <linux/of.h>
> > -#include <linux/of_device.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/property.h>
> >  #include <linux/reboot.h>
> >  #include <linux/stat.h>
> >  #include <linux/vexpress.h>
> > @@ -108,20 +108,17 @@ static int _vexpress_register_restart_handler(struct device *dev)
> >  
> >  static int vexpress_reset_probe(struct platform_device *pdev)
> >  {
> > -	const struct of_device_id *match =
> > -			of_match_device(vexpress_reset_of_match, &pdev->dev);
> > +	enum vexpress_reset_func func;
> >  	struct regmap *regmap;
> >  	int ret = 0;
> >  
> > -	if (!match)
> > -		return -EINVAL;
> > -
> >  	regmap = devm_regmap_init_vexpress_config(&pdev->dev);
> >  	if (IS_ERR(regmap))
> >  		return PTR_ERR(regmap);
> >  	dev_set_drvdata(&pdev->dev, regmap);
> >  
> > -	switch ((uintptr_t)match->data) {
> > +	func = (uintptr_t)device_get_match_data(&pdev->dev);
> > +	switch (func) {
> >  	case FUNC_SHUTDOWN:
> >  		vexpress_power_off_device = &pdev->dev;
> >  		pm_power_off = vexpress_power_off;
> 
> device_get_match_data() is badly un-documented but I think it can still
> return NULL if no match. At the moment we're checking for a match earlier
> and avoid calling devm_regmap_init_vexpress_config() needlessly, with your
> patch not so. Can you not replace each line with the equivalent code and
> keep the NULL check?

In contrast, I always questioned/wondered why we needed the NULL check
for the match above as probe would have not got called if there was no
match. While I agree with the less clear documentation of
device_get_match_data(), I am fine with the change as such

Acked-by: Sudeep Holla <sudeep.holla@arm.com>

Also check similar response from Rob here[1]

Sebastian,

I assume you will pick this up.

--
Regards,
Sudeep

[1] https://lore.kernel.org/all/CAL_JsqKi8PXVqHgVxqMN+mbX8U-ZGsCMUFqbxmjeFmj1xKTrjw@mail.gmail.com/