Re: [RFC v1 PATCH 1/3] drivers: soc: add support for soc_device_match returning -EPROBE_DEFER

Dan Carpenter
2021-04-20T11:57:08Z

On Mon, Apr 19, 2021 at 10:20:13AM +0200, Geert Uytterhoeven wrote:
> Hi Alice,
>
> CC Arnd (soc_device_match() author)
>
> On Mon, Apr 19, 2021 at 6:28 AM Alice Guo (OSS) <alice.guo@oss.nxp.com> wrote:
> > From: Alice Guo <alice.guo@nxp.com>
> >
> > In i.MX8M boards, the registration of SoC device is later than caam
> > driver which needs it. Caam driver needs soc_device_match to provide
> > -EPROBE_DEFER when no SoC device is registered and no
> > early_soc_dev_attr.
>
> I'm wondering if this is really a good idea: soc_device_match() is a
> last-resort low-level check, and IMHO should be made available early on,
> so there is no need for -EPROBE_DEFER.
>
> >
> > Signed-off-by: Alice Guo <alice.guo@nxp.com>
>
> Thanks for your patch!
>
> > --- a/drivers/base/soc.c
> > +++ b/drivers/base/soc.c
> > @@ -110,6 +110,7 @@ static void soc_release(struct device *dev)
> > }
> >
> > static struct soc_device_attribute *early_soc_dev_attr;
> > +static bool soc_dev_attr_init_done = false;
>
> Do you need this variable?
>
> >
> > struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
> > {
> > @@ -157,6 +158,7 @@ struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr
> > return ERR_PTR(ret);
> > }
> >
> > + soc_dev_attr_init_done = true;
> > return soc_dev;
> >
> > out3:
> > @@ -246,6 +248,9 @@ const struct soc_device_attribute *soc_device_match(
> > if (!matches)
> > return NULL;
> >
> > + if (!soc_dev_attr_init_done && !early_soc_dev_attr)
>
> if (!soc_bus_type.p && !early_soc_dev_attr)

There is one place checking this already. We could wrap it in a helper
function:

static bool device_init_done(void)
{
return soc_bus_type.p ? true : false;
}

regards,
dan carpenter