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

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Date:   Wed, 19 Aug 2020 16:16:01 +0800
From:   Icenowy Zheng <icenowy@...c.io>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mfd: core: Fix handle of OF disabled MFD cells

在 2020-08-19星期三的 09:11 +0100，Lee Jones写道：
> 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.

I think it's okay.

I will test it once it's out.

> 
> > 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;
> >  			}