Hi Valentine,
On 24.11.2015 17:02, Valentin Longchamp wrote:
<snip>
Does your board use driver model from SPI and SPI flash? If not I
think that should be the first step.
No we don't. Could you please elaborate on how this would cover this use case
and should be the first step ?
I am open to other ways to cover this use case of ours, especially since this
was done more than 2 years ago and u-boot has changed since then. However I
don't see the direct link between the driver model and how it would allow to
make sure spi_flash_free() is called in our u-boot env scripts.
In driver model you would have a remove() method for your SPI driver
which does the required pinmux changing.
OK, when looking at SPI flash, SPI controller driver and the driver model, I
have found out why we require this "release" command.
So the SPI subsystem and its drivers (with or without DM support) make sure that
spi_claim_bus/release_bus are called before/after the accesses. This should
cover the pinmux configuration stuff.
In our case, it was not sufficient since drivers/spi/kirkwood_spi.c does the
pinmux configuration at 2 places: spi_claim_bus/release_bus for the IO
(MOSI/MISO/CLK) AND spi_setup_slave/free_slave for the chip select.
Since spi_free_slave is not always called after spi_setup_slave (for instance
after a sf probe command on the u-boot prompt), the CS pin was not always given
back to the NAND flash controller that's why there was a need for a sf release
command in our case.
I have now moved all the pinmux configuration for kirkwood_spi into
spi_claim_bus/release_bus and the need for this sf release command is not
necessary anymore.
I am going to test this a bit more and send a new patch series which will not
require this release command.
There is a detailed howto in doc/driver-model showing how to port your
driver over. Please let me know if you need any help/ideas.
I have had a look at it and it is a great help on porting a driver to this
model. That's something we plan to do for our boards eventually.
So did you already port the kirkwood SPI driver to DM? I'm asking, since
I also do have a patch for this in the queue. I'll hopefully be able
to post it by end of this week.
BTW: I would love to see the Kirkwood platform to be moved over to
arch-mvebu at some time, which already supports DM.
Thanks,
Stefan
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