Re: [PATCH] leds: tlc591xx: update the maximum brightness

[Jean-Jacques Hiblot]

On 13/10/2019 18:36, Jacek Anaszewski wrote:
> On 10/13/19 1:45 PM, Pavel Machek wrote:
> > Hi!
> >
> > > > @@ -112,11 +113,11 @@ tlc591xx_brightness_set(struct led_classdev *led_cdev,
> > > >   	struct tlc591xx_priv *priv = led->priv;
> > > >   	int err;
> > > >   
> > > > -	switch (brightness) {
> > > > +	switch ((int)brightness) {
> > > >   	case 0:
> > Can we get a rid of the cast here? Do we need to move away from the
> > enum for the brightness?
> I at first also wanted to ask for dropping the cast but first tried
> to do it myself. Then I found out compiler (or sparse, I don't recall
> exactly) complains about TLC591XX_MAX_BRIGHTNESS not being a value of
> enum led_brighteess type. That's the reason for the cast Jean added,
> I presume.

Indeed that cast is to fix the warning.

JJ

> > > Added tag:
> > >
> > > Fixes: e370d010a5fe ("leds: tlc591xx: Driver for the TI 8/16 Channel i2c
> > > LED driver")
> > >
> > > and applied to the for-5.5 branch.
> > Actually, careful with the Fixes tag. -stable people will want to
> > apply it, and it may not be a good idea in this case. Maximum
> > brightness of 256 is pretty unusual, so I'd call this "a bit risky".
> I entirely disagree. Not seeing anything risky in that since
> max_brightness is also initialized to this value. If userspace properly
> uses the ABI, then it will be safe.
>
> > Best regards,
> > 									Pavel