Messages in this thread | | | Date | Wed, 5 Nov 2014 01:34:30 -0800 | From | Brian Norris <> | Subject | Re: [PATCH 01/27] mtd: nand: introduce function to fix a common bug in most nand-drivers not showing a device in sysfs |
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On Sun, Nov 02, 2014 at 10:03:53PM +0100, Frans Klaver wrote: > On Wed, May 28, 2014 at 01:43:44AM -0700, Brian Norris wrote: > > And in fact, if any drivers are missing mtd->name, perhaps it's best to > > just modify the MTD registration to give them a default: > > > > if (!mtd->name) > > mtd->name = dev_name(&pdev->dev); > > > > ... > > > How about we rethink the "helper" approach, and instead just do > > validation in the core code? This would cover most of the important > > parts of your helper, I think: > > > > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > > index d201feeb3ca6..39ba5812a5a3 100644 > > --- a/drivers/mtd/mtdcore.c > > +++ b/drivers/mtd/mtdcore.c > > @@ -397,6 +397,11 @@ int add_mtd_device(struct mtd_info *mtd) > > if (device_register(&mtd->dev) != 0) > > goto fail_added; > > > > + if (mtd->dev.parent) > > + mtd->owner = mtd->dev.parent->driver->owner; > > + else > > + WARN_ON(1); > > + > > So I've picked this up now. I do largely agree with the suggested > approach where the validation and default settings are done in the core > code. There is a problem with this, though. There are MTD devices that > call mtd_device_parse_register() in the _init() function (such as the > maps drivers). These don't have a device ready to be used as parent, and > they would always be throwing this warning.
Yeah, I came across the same thing. I think gluebi is another example.
> So either not having a parent device is bad, or it isn't. The comment > suggests it is, the existing code suggests it isn't. So we'll need to > make a decision about who's right.
I think not having a parent is not really bad. It's helpful for tracking the device hierarchy in sysfs, but it's not strictly necessary. So we should probably not do anything drastic like WARN_ON() yet.
> > if (MTD_DEVT(i)) > > device_create(&mtd_class, mtd->dev.parent, > > MTD_DEVT(i) + 1, > > diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c > > index 1ca9aec141ff..9869bbef50cf 100644 > > --- a/drivers/mtd/mtdpart.c > > +++ b/drivers/mtd/mtdpart.c > > @@ -370,7 +370,6 @@ static struct mtd_part *allocate_partition(struct mtd_info *master, > > slave->mtd.subpage_sft = master->subpage_sft; > > > > slave->mtd.name = name; > > - slave->mtd.owner = master->owner; > > What would be the purpose of removing this line? Owner is already set? > Can we rely on that?
I'm not completely sure why I wrote that, but I think the only call site for alloc_partition() is in mtd_add_partition(), which calls add_mtd_device().
Brian
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