linux-kernel - Re: [PATCH 1/1] mfd: mfd-core: Ensure disabled devices are ignored without error

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Date:   Wed, 19 Aug 2020 21:00:41 +0800
From:   Icenowy Zheng <icenowy@...c.io>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/1] mfd: mfd-core: Ensure disabled devices are ignored
 without error

在 2020-08-19星期三的 11:54 +0100，Lee Jones写道：
> Commit e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match
> devices with the correct of_nodes") changed the semantics for
> disabled
> devices in mfd_add_device().  Instead of silently ignoring a disabled
> child device, an error was returned.  On receipt of the error
> mfd_add_devices() the precedes to remove *all* child devices and
> returns an all-failed error to the caller, which will inevitably fail
> the parent device as well.
> 
> This patch reverts back to the old semantics and ignores child
> devices
> which are disabled in Device Tree.
> 
> Fixes: e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match
> devices with the correct of_nodes")
> Reported-by: Icenowy Zheng <icenowy@...c.io>
> Signed-off-by: Lee Jones <lee.jones@...aro.org>

Tested-by: Icenowy Zheng <icenowy@...c.io>

> ---
>  drivers/mfd/mfd-core.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index c3651f06684fa..30f90a15ceaab 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -126,10 +126,6 @@ static int mfd_match_of_node_to_dev(struct
> platform_device *pdev,
>  	const __be32 *reg;
>  	u64 of_node_addr;
>  
> -	/* Skip devices 'disabled' by Device Tree */
> -	if (!of_device_is_available(np))
> -		return -ENODEV;
> -
>  	/* Skip if OF node has previously been allocated to a device */
>  	list_for_each_entry(of_entry, &mfd_of_node_list, list)
>  		if (of_entry->np == np)
> @@ -212,6 +208,12 @@ static int mfd_add_device(struct device *parent,
> int id,
>  	if (IS_ENABLED(CONFIG_OF) && parent->of_node && cell-
> >of_compatible) {
>  		for_each_child_of_node(parent->of_node, np) {
>  			if (of_device_is_compatible(np, cell-
> >of_compatible)) {
> +				/* Ignore 'disabled' devices error free
> */
> +				if (!of_device_is_available(np)) {
> +					ret = 0;
> +					goto fail_alias;
> +				}
> +
>  				ret = mfd_match_of_node_to_dev(pdev,
> np, cell);
>  				if (ret == -EAGAIN)
>  					continue;