Re: [PATCH 5/5] firmware: add DECLARE_FW_CUSTOM_FALLBACK() annotation

Luis R. Rodriguez
2016-12-16T09:59:17Z

On Fri, Dec 16, 2016 at 10:29:20AM +0100, Pavel Machek wrote:
> On Fri 2016-12-16 10:22:41, Luis R. Rodriguez wrote:
> > On Tue, Dec 13, 2016 at 08:04:29PM +0100, Pavel Machek wrote:
> > > Hi!
> > >
> > > > We need to ensure that when driver developers use the custom firmware
> > > > fallback mechanism it was not a copy and paste bug. These use cases on
> > > > upstream drivers are rare, we only have 2 upstream users and its for
> > > > really old drivers. Since valid uses are rare but possible enable a
> > > > white-list for its use, and use this same white-list annotation to refer
> > > > to the documentation covering the custom use case.
> > >
> > > > --- a/drivers/leds/leds-lp55xx-common.c
> > > > +++ b/drivers/leds/leds-lp55xx-common.c
> > > > @@ -219,6 +219,7 @@ static void lp55xx_firmware_loaded(const struct firmware *fw, void *context)
> > > > release_firmware(chip->fw);
> > > > }
> > > >
> > > > +DECLARE_FW_CUSTOM_FALLBACK("Documentation/leds/leds-lp55xx.txt");
> > > > static int lp55xx_request_firmware(struct lp55xx_chip *chip)
> > > > {
> > > > const char *name = chip->cl->name;
> > >
> > > The driver does:
> > >
> > > static void lp55xx_firmware_loaded(const struct firmware *fw, void
> > > *context)
> > > {
> > > struct lp55xx_chip *chip = context;
> > > struct device *dev = &chip->cl->dev;
> > > enum lp55xx_engine_index idx =
> > > chip->engine_idx;
> > >
> > > if (!fw) {
> > > dev_err(dev, "firmware request failed\n");
> > > goto out;
> > > }
> > > ...
> > > out:
> > > /* firmware should be released for other channel use */
> > > release_firmware(chip->fw);
> > > }
> > >
> > >
> > > Does that match the "custom fallback" definition?
> >
> > Refer to the documentation I supplied, and also to the grammar rule, in
> > particular the patch "firmware: add SmPL report for custom fallback mechanism",
> > it captures the SmPL form for the custom fallback mechanism as:
>
> I don't much care what the rule says. If you believe the code is
> buggy, submit a patch.

Huh? No, its an old API and valid uses are scarce. The point is to avoid folks
adding yet other users by mistake by using grammar to help white-list actual
valid users.

Luis