Messages in this thread | | | From | Marek Vasut <> | Subject | Re: [PATCH 1/5] mtd: ofpart: grab device tree node directly from master device node | Date | Wed, 28 Oct 2015 21:38:20 +0100 |
| |
On Wednesday, October 28, 2015 at 05:32:15 PM, Boris Brezillon wrote: > Hi Marek,
Hi Boris,
> On Wed, 28 Oct 2015 17:11:14 +0100 > > Marek Vasut <marex@denx.de> wrote: > > On Wednesday, October 28, 2015 at 08:58:13 AM, Boris Brezillon wrote: > > > Hi Brian, > > > > Hi, > > > > [...] > > > > > > Are > > > > there ever cases we want more than one (master) MTD per nand_chip? Or > > > > vice versa? > > > > > > Nope, I'd say that you always have a 1:1 relationship between a master > > > MTD device and a NAND device. > > > > Do some sorts of chipselects come into play here ? Ie. you can have one > > master with multiple NAND chips connected to it. > > Most NAND controllers support interacting with several chips (or > dies in case your chip embeds several NAND dies), but I keep thinking > each physical chip should have its own instance of nand_chip + mtd_info. > If you want to have a single mtd device aggregating several chips you > can use mtdconcat.
I agree.
> This leaves the multi-dies chip case, and IHMO we should represent those > chips as a single entity, and I guess that's the purpose of the > ->numchips field in nand_chip (if your chip embeds 2 dies with 2 CS > lines, then ->numchips should be 2).
I'd expect this to be represented as two physical chips, no ?
> Anyway, I think the whole problem here is that most NAND drivers are > mixing the concepts of NAND controller (the controller driving one or > several NAND chips) and NAND chip (a chip connected to a NAND > controller). > The NAND controller should not be represented with a nand_chip > instance, but with a nand_hw_control instance, which is rarely done > except in a few drivers.
OK, understood.
> I sent an RFC a while ago [1] to clarify that, but didn't have time to > post a new version. > > Best Regards, > > Boris > > [1]http://thread.gmane.org/gmane.linux.drivers.mtd/57614/focus=58552
Best regards, Marek Vasut
| |