-----Original Message----- From: Valentin Longchamp [mailto:valentin.longchamp@keymile.com] Sent: 29 March 2012 21:15 To: Prafulla Wadaskar Cc: u-boot@lists.denx.de; Gerlando Falauto; Holger Brunck Subject: Re: [PATCH v2] spi/kirkwood: add weak functions board_spi_bus_claim/release
Hi Prafulla,
On 03/29/2012 02:49 PM, Valentin Longchamp wrote:
On 03/28/2012 09:48 AM, Prafulla Wadaskar wrote:
Basically spi_claim_bus and spi_release_bus are not supported in
current Kirkwood spi driver.
These are needed if someone wish to share the same interface pins
with some other peripheral (that is your use case)
Correct, this is exactly our use case: we have the NAND Flash
Controller and the
SPI controller that share the same pins.
But this is not board specific whereas, it should be feature
enhancement for Kirkwood spi driver.
This is correct for the mpp part of spi_claim_bus. If you look at
the actual
implementation that we do in our board specific function, there is
an additional
step that is needed by our board design.
I have started to implement this, and now I see that with your approach of doing the mpp part in the driver does not work and my proposed solution of doing this with board specific functions is the correct one:
The SPI_SI, SPI_SCK, SPI_CSn all can be used with different mpp configuration. This is a board design parameter. How can the driver know which one is used on the board ?
Dear Valentin You should keep by default NF configuration in your board configuration (kwmpp_config), so this becomes your default mpp configuration.
If SPI flash is being accessed, all spi_flash calls are guarded with claim_bus and release_bus APIs.
In Kirkwood specific claim_bus API, you will backup default configuration (which is NF in your case) for these particular pins (SPI_SI, SPI_SCK, SPI_CSn, MOSI, MISO).
and in release_bus API, you will reconfigure backed-up mpp configuration (which will be NF in your case).
With this you don't need km_hw_spi_bus_claim() or do_spi_toggle() in your board specific code any more.
How come this doesn't work? It should work, if not let's debug the problem.
Regards.. Prafulla . . .