[PATCH 3/3] soc: imx: gpcv2: split PGC domain probe in two passes

[Peng Fan]

> Subject: [PATCH 3/3] soc: imx: gpcv2: split PGC domain probe in two passes
> 
> Since 5a46079a9645 ("PM: domains: Delete usage of
> driver_deferred_probe_check_state()")
> power domain consumers attached by the driver core do not support probe
> deferral anymore, as it is assumed that they are only probed after the
> provider is present, as a devlink should have been established between the
> two.
> 
> With the GPCv2 and its slightly unusual mix between platform devices and
> DT description for the PGC domains, devlink fails to add the neccessary
> probe dependency. Now that probe deferral is not an option anymore, the
> domain drivers for nested GPC domains simply fail to probe, leaving parts of
> the SoC unusable. Rather than trying to teach devlink about our one-off
> usage of DT and platform devices, just split the registration of the nested
> power domains into a second pass, so that we never need any dependency
> handling.
> 
> Fixes: 5a46079a9645 ("PM: domains: Delete usage of
> driver_deferred_probe_check_state()")

This regression has been fixed, the patch author reverted that patch.

Do we still need this fix?

Thanks,
Peng.
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> ---
>  drivers/soc/imx/gpcv2.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c index
> 6383a4edc360..d1bbadbcb034 100644
> --- a/drivers/soc/imx/gpcv2.c
> +++ b/drivers/soc/imx/gpcv2.c
> @@ -1446,7 +1446,7 @@ static int imx_gpcv2_probe(struct
> platform_device *pdev)
>  	struct device_node *pgc_np, *np;
>  	struct regmap *regmap;
>  	void __iomem *base;
> -	int ret;
> +	int ret, pass = 0;
> 
>  	pgc_np = of_get_child_by_name(dev->of_node, "pgc");
>  	if (!pgc_np) {
> @@ -1465,7 +1465,16 @@ static int imx_gpcv2_probe(struct
> platform_device *pdev)
>  		return ret;
>  	}
> 
> +	/*
> +	 * Run two passes for the registration of the PGC domain platform
> +	 * devices: first all devices that are not part of a power-domain
> +	 * themselves, then all the others. This avoids -EPROBE_DEFER being
> +	 * returned for nested domains, that need their parent PGC domains
> +	 * to be present on probe.
> +	 */
> +again:
>  	for_each_child_of_node(pgc_np, np) {
> +		bool child_domain = of_property_read_bool(np, "power-
> domains");
>  		struct platform_device *pd_pdev;
>  		struct imx_pgc_domain *domain;
>  		u32 domain_index;
> @@ -1473,6 +1482,9 @@ static int imx_gpcv2_probe(struct
> platform_device *pdev)
>  		if (!of_device_is_available(np))
>  			continue;
> 
> +		if ((pass == 0 && child_domain) || (pass == 1
> && !child_domain))
> +			continue;
> +
>  		ret = of_property_read_u32(np, "reg", &domain_index);
>  		if (ret) {
>  			dev_err(dev, "Failed to read 'reg' property\n"); @@
> -1522,6 +1534,11 @@ static int imx_gpcv2_probe(struct platform_device
> *pdev)
>  		}
>  	}
> 
> +	if (pass == 0) {
> +		pass++;
> +		goto again;
> +	}
> +
>  	return 0;
>  }
> 
> --
> 2.30.2