On Mon, Jun 25, 2018 at 8:25 PM, Tom Rini trini@konsulko.com 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 jagan@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'm not denying that, but the basic design flow must follow u-boot driver model. this is what everyone told from the beginning when I started spi-nor work. Initially I did the design like this and leverage with existing MTD, everyone NAK and suggested to use driver-model on each stage with MTD dm abstraction. So - After 2 years of work - With nearly 10 versions [4] - Adding MIGRATION expire date for spi drivers dm conversion - Simon Reviewed-by and - Planning to apply after v2018.09.
but now all want the existing MTD, I don't understand what I can do further on this?
[4] https://patchwork.ozlabs.org/user/todo/uboot/?series=20450