Subject: [PATCH 07/12] hwrng: bcm2835-rng: Manage an optional clock

From: [email-masked] (Andrew Lunn)
Date: Sat, 4 Nov 2017 20:37:31 +0100

Hi Florian

> > >> +	/* Clock is optional on most platforms */
> > >> +	priv->clk = devm_clk_get(dev, NULL);
> > >> +	if (IS_ERR(priv->clk))
> > >> +		priv->clk = NULL;
> > > 
> > > at least in case of EPROBE_DEFERED this isn't the expected behavior. Maybe we should better trigger on non-existing clock?
> > 
> > Good point, so more like:
> > 
> > if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -ENODEV)?
> 

> Unfortunately we need to return the error in all other cases. Please
> take a look at devm_usb_get_phy in dwc2 [1]. AFAIK we don't need to
> take care of ENXIO in our case.

A few subsystems have a get_optional() call, e.g.
devm_phy_optional_get(). It does not return an error when the phy is
not supposed to exist, but in all other cases, it does.

Maybe consider adding devm_clk_get_optional()?

      Andrew