[PATCH] mtd: powernv: Support MTD_NO_ERASE

[Michael Ellerman]

William Kennington <wak at google.com> writes:

> +Cyril Bur and
>
> Not sure what you mean by mainline, but the commit is in the master branch
> at
> https://github.com/open-power/skiboot/commit/ba99af9b149d02438347b055e6e7d6bd15e33551

I suspect Boris missed that you were referring to a skiboot commit and
looked in Linux?

> I'm unsure about the documentation of the properties as I'm not really the
> maintainer of any of the code on either side. I just added this DT property
> for plumbing through the NO_ERASE flag. I added Cyril and Michael as they
> both work closely with this driver and could comment better than I could.
>
> - William
>
> On Thu, Sep 21, 2017 at 12:59 AM Boris Brezillon <
> boris.brezillon at free-electrons.com> wrote:
>
>> +the DT maintainers
>>
>> On Tue,  5 Sep 2017 13:23:39 -0700
>> "William A. Kennington III" <wak at google.com> wrote:
>>
>> > As of skiboot at ba99af9b149d02438347b055e6e7d6bd15e33551, we now support
>>
>> I didn't find this commit in mainline.
>>
>> > adding a device tree entry which marks a flash device as not needing
>> > erase. This patch adds support for setting MTD_NO_ERASE on powernvflash
>> > devices which have the property no-erase.
>> >
>> > Signed-off-by: William A. Kennington III <wak at google.com>
>> > ---
>> >  drivers/mtd/devices/powernv_flash.c | 2 ++
>> >  1 file changed, 2 insertions(+)
>> >
>> > diff --git a/drivers/mtd/devices/powernv_flash.c
>> b/drivers/mtd/devices/powernv_flash.c
>> > index f5396f26ddb4..fab9f9121b4c 100644
>> > --- a/drivers/mtd/devices/powernv_flash.c
>> > +++ b/drivers/mtd/devices/powernv_flash.c
>> > @@ -196,6 +196,8 @@ static int powernv_flash_set_driver_info(struct
>> device *dev,
>> >       mtd->name = of_get_property(dev->of_node, "name", NULL);
>> >       mtd->type = MTD_NORFLASH;
>> >       mtd->flags = MTD_WRITEABLE;
>> > +     if (of_property_read_bool(dev->of_node, "no-erase"))
>> > +             mtd->flags |= MTD_NO_ERASE;
>>
>> I don't see this property document in a DT binding doc, which is
>> mandatory. Actually, there's no DT bindings doc at all for the
>> 'ibm,opal-flash' device in mainline, is this normal?

The binding doc is here:

  https://github.com/open-power/skiboot/blob/master/doc/device-tree/ibm%2Copal/flash.rst

But that property is not documented :(

We have some of the skiboot bindings also in the kernel tree, but there
was talk of moving all the binding docs *out* of the kernel, so we never
made an effort to put more in. I've lost track of whether there are
still plans to move the binding docs out or not.

cheers