On Thu, Dec 6, 2018 at 11:55 PM Vignesh R <[email protected]> wrote: > > Hi Jagan, > > On 06-Dec-18 10:44 PM, Jagan Teki wrote: > > On Tue, Dec 4, 2018 at 5:56 PM Vignesh R <[email protected]> wrote: > >> > >> U-Boot SPI NOR support (sf layer) is quite outdated as it does not > >> support 4 byte addressing opcodes, SFDP table parsing and different types > >> of > >> quad mode enable sequences. Many newer flashes no longer support BANK > >> registers used by sf layer to a access >16MB space. > >> Also, many SPI controllers have special MMIO interfaces which provide > >> accelerated read/write access but require knowledge of flash parameters > >> to make use of it. Recent spi-mem layer provides a way to support such > >> flashes but sf layer isn't using that. > >> This patch series syncs SPI NOR framework from Linux v4.19. It also adds > >> spi-mem support on top. > >> So, we gain 4byte addressing support and SFDP support. This makes > >> migrating to U-Boot MTD framework easier. > > > > We(someone) has proposed this sync before, but we(at-least I) rely on > > implementing via DM not direct sync to Linux. > > As I said in my cover letter, U-Boot sf layer is unable to support newer > flashes mainly due to lack of 4 byte addressing and proper support for > MMIO capable SPI controllers. > My idea of fixing this is to borrow _features_ from Linux SPI NOR "as > is". All that's needed is stateless 4 byte addressing, SFDP > parsing(optionally), Quad/Octal support and spi-mem like abstraction for > MMIO capable Controllers. I see no point in re-coding them from ground up. > > Could you be more specific on what you would like to see here in DM way? > I have no issues in adapting this code to any framework here in U-Boot. > Linux has driver model and SPI NOR subsystem is a framework and > therefore any code ported from Linux will inherently have those > abstractions. The only difference I see wrt your code in branch below vs > this series is SPI-NOR uclass. This can be easily achieved by moving > nor->ops out of struct spi_nor into uclass abstraction. > Upstream Linux is anyways merging m25p80 and spi-nor so I did not see a > need for SPI NOR uclass. I am okay to change that if you insist on > having it.
Merging or syncing spi-nor features stuff from Linux is good, I'm not stopping that. but this can be do by satisfying u-boot driver-model with proper architectural model. I know you take care but I'm not sure ie what can be manageable for long term. Let's discuss the proper architectural model, so-that we can move further to incorporate the changes accordingly. (thanks at last we have a thread to discuss) Linux m25p80 is moved to spi-nor right? so does controllers on spi-nor should be reside in same area like drivers/mtd/spi-nor or it should be part of spi-mem. The last mail with Boris, noted all spi-nor can't be fit into spi-mem(sorry I lost the thread) Example: we have zynq qspi it support BAR(with >16MB flashes), dual qspi ect so does it comes under spi-mem or spi-nor? So, if no driver should be part of spi-nor and all can be handle spi-mem even-though they have controller specific features, yes we can skip SPI_NOR_UCLASS otherwise we need spi-nor uclass that can be child uclass of MTD. _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
