Re: [PATCH 2/2] mtd: spi-nor: add initial sysfs support

[Michael Walle]

Hi,

Am 2021-04-06 09:56, schrieb Vignesh Raghavendra:
> Hi,
>
> On 3/18/21 2:54 PM, Michael Walle wrote:
> > Add support to show the name and JEDEC identifier as well as to dump 
> > the
> > SFDP table. Not all flashes list their SFDP table contents in their
> > datasheet. So having that is useful. It might also be helpful in bug
> > reports from users.
>
> Sorry for the delay..
>
> There is already debugfs support for dumping JEDEC ID [1]. Any reason 
> to
> add sysfs entry as well?

This is per mtd while the sfdp is per flash device. IMHO both should
be at the same place.

> That brings up another question. Since SFDP dumps are more of a debug
> aid, should this be a debugfs entry rather than sysfs entry?

And you're not the first one asking that. My argument was that the
debugfs might not be available just when you need it. A developer
could easily rebuild a kernel, but imagine some user with a COTS
distro and some problems, then it is not that easy anymore. But
thats your call to make.

> Note that sysfs entries are userspace ABIs just like syscalls and thus
> need to be documented in Documentation/ABI/testing/ or
> Documentation/ABI/stable. Thus need to be carefully designed compared 
> to
> debugfs which are much more flexible.

Ok. But I don't see a problem adding these read-only files
 /sfdp
 /name
 /jedec-id

Do you?

-michael