On 25.06.2018 16:55, Tom Rini wrote:
On Mon, Jun 25, 2018 at 04:46:56PM +0200, Boris Brezillon wrote:
On Mon, 25 Jun 2018 19:58:37 +0530
Jagan Teki <ja...@amarulasolutions.com> wrote:
- convert fsl-qspi to spi-mem
We're not targeting the fsl-qspi controller here but a simple SPI
controller that is already upstreamed. But yes, the fsl-qspi driver
will have to be patched to support the spi-mem interface at some point.
Can you point me that simple spi-mem controller driver?
It's not a controller that implements spi-mem operations but a simple
SPI controller (one that knows how to do regular SPI transfers and
nothing more). But the spi-mem layer knows how to send spi_mem_op using
regular transfer and that's why it works without any modification at
the driver level.
For spi-nor interface design, we have an example code here[2]
I've paused this [2] series because of dm conversion of spi-drivers
otherwise I need add legacy code like mmc-legacy.c, so if we really
move to spi-mem design and okay with above design. I will try to move
the current spi flash to add MTD driver-model so-that we can add
spi-mem, spi-nand on top of it or we can work together to convert them
all.
Why can't we do things iteratively. I mean, if the long term goal is to
convert everything to the driver model, then this patchset is going in
the right direction:
- addition of DM helpers to the MTD_UCLASS
- addition of the spi-mem interface properly integrated in the DM
model of the SPI framework
- addition of a SPI NAND driver, again properly integrated in the DM
- integration of DM-ready MTD drivers and old MTD drivers in a single
view exposed by the cmd/mtd.c command set
I'd really like to limit the scope of this development to these topics,
which doesn't prevent you from converting other part of u-boot to the
spi-mem approach (SPI NOR is one example).
I hope you understand our concerns and the fact that what you're asking
us to do as a dependency of getting SPI NAND support + cmd/mtd.c merged
is way more than we can actually provide.
To answer all these questions, I think we need to decide whether we go
for MTD dm abstraction or existing MTD layer.
When I say MTD dm abstraction, all mtd operation prototypes are in the
form of udevice unlike existing MTD has mtd_info. when I initially
supporting spi-nor (during Linux early spi-nor) I've reused existing
MTD and written something like what Miquel did using mtd_info ops [3].
but then developers on ML, proposed the new drivers should be form of
driver-model abstraction, so I've added mtd driver model ops [4].
I understand the new MTD dm abstraction in U-Boot is not possible for
direct syncing from Linux, but we really want the u-boot way of
handling drivers and trying to copy code from Linux by removing
__UBOOT__ or any Linux specific macros. Since this is pretty much big
task, ie the reason I'm asking for single driver from each MTD device
so-that once the clear stack is ready other drivers can convert
one-by-one.
I think I have to repeat my previous statement here. It would be very
unfortunate if u-boot decides to take this direction (see Richard's
reply), especially since I see absolutely no benefit in doing what you
suggest. Having MTD devices registered to the uboot DM is something I
can understand, deciding to no longer support the standard MTD API is
something I don't.
I agree. We want U-Boot to be able to leverage as much as possible from
the Linux kernel with as little re-working as possible.
I wholeheartedly agree on this.
Thanks,
Stefan
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
https://lists.denx.de/listinfo/u-boot
