On Tue, Oct 27, 2015 at 10:54:46AM -0700, Brian Norris wrote: > On Tue, Oct 27, 2015 at 08:42:00AM +0100, Boris Brezillon wrote: > > On Mon, 26 Oct 2015 19:31:06 -0700 > > I like the idea, but how about pushing the solution even further and > > killing the ->flash_node field which AFAICT is rendered useless by > > your patch? > > I suppose we could do that. I do think there's something to be said for > layering, though. Historically, we haven't done a very good job of > layering in MTD, so low-level drivers often have to poke around in the > MTD structures, even if they really should only have to know a few > things about their helper subsystem/library, like NAND or SPI NOR. So > with that in mind, I think the ->flash_node serves some purpose -- > drivers can just initialize struct nand_chip/spi_nor and be assured that > the NAND/SPI-NOR subsystems will take care of things. > > Now, I don't think there's much reason to suspect that we'd have a more > complex mapping than 1:1 between struct mtd_info and struct nand_chip or > struct spi_nor, so maybe we don't actually need duplicate storage > (mtd.dev.of_node and {spi_nor,nand_chip}.flash_node), and the layering > is just have these APIs: > > nand_set_flash_node() > spi_nor_set_flash_node() > > which just call mtd_set_of_node()?
I looked at this quickly for NAND, and it's hard to do right now because of the below quote. The SPI NOR layering is better though, so that works. Mind if I defer the dropping the flash_node in NAND but do the SPI NOR one? > Speaking of layering: why do we have NAND drivers initializing mtd->priv > for us, yet nand_base just assumes that it points to a struct nand_chip? > And why isn't struct mtd_info just embedded in struct nand_chip? Are > there ever cases we want more than one (master) MTD per nand_chip? Or > vice versa? The layering (or lack thereof) make it hard to extract a struct mtd_info from a struct nand_chip. Brian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/