linux-kernel - Re: [PATCH] mfd: core: Fix handle of OF disabled MFD cells

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Message-ID: <20200819081122.GB4354@dell>
Date:   Wed, 19 Aug 2020 09:11:22 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Icenowy Zheng <icenowy@...c.io>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mfd: core: Fix handle of OF disabled MFD cells

On Sat, 01 Aug 2020, Icenowy Zheng wrote:

> When rewriting the OF match code of MFD core, addition of cells disabled
> in OF will result in a failure with error -ENODEV. This is an unexpected
> behavior, as the previous behavior is silently ignore the cell. On
> SBCs with AXP20x PMICs, this leads to boot failure if AXP20x PMIC
> support is built-in and some cells (especially power supply ones) are
> disabled.

Thanks for reporting this.

Do you mind if I fix this another way?  I plan to reinstate the old
code that was removed as part of the offending patch.  I will of
course add your Reported-by tag.

> Silently ignore the cell when -ENODEV occurs.
> 
> Fixes: e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
> ---
>  drivers/mfd/mfd-core.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index c3ef58a802bee..31b363c64f4b4 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -215,8 +215,13 @@ static int mfd_add_device(struct device *parent, int id,
>  				ret = mfd_match_of_node_to_dev(pdev, np, cell);
>  				if (ret == -EAGAIN)
>  					continue;
> -				if (ret)
> +				if (ret) {
> +					if (ret == -ENODEV) {
> +						/* Ignore disabled devices error free */
> +						ret = 0;
> +					}
>  					goto fail_alias;
> +				}
>  
>  				break;
>  			}

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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