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

Geert Uytterhoeven
2021-04-19T08:20:29Z

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)

> + return ERR_PTR(-EPROBE_DEFER);
> +
> while (!ret) {
> if (!(matches->machine || matches->family ||
> matches->revision || matches->soc_id))

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds