Hi Valentine, On 23 November 2015 at 02:19, Valentin Longchamp <valentin.longch...@keymile.com> wrote: > Hi Simon, > > On 20/11/2015 18:19, Simon Glass wrote: >> Hi, >> >> On 20 November 2015 at 03:13, Valentin Longchamp >> <valentin.longch...@keymile.com> wrote: >>> On 19/11/2015 17:57, Jagan Teki wrote: >>>> On 13 November 2015 at 18:55, Valentin Longchamp >>>> <valentin.longch...@keymile.com> wrote: >>>>> The release command is the pendant of the probe command. This command >>>>> allows to call spi_flash_free from the command line. This may be >>>>> necessary for some boards where sf probe does change the state of the >>>>> hardware (like with some pin multiplexing changes for instance). >>>> >>>> So you want to change the state of pin multiplexing on your board with >>>> connected slave devices example: spi nor flash is it? what exactly the >>>> need of releasing? why can't we use pin multiplexing changes like >>>> selecting or deselecting particular lines through driver or from board >>>> files itself. >>> >>> That's our use case yes. Let me explain you it again in detail. Some of the >>> signals used to access the NAND Flash and the SPI NOR are shared. At reset, >>> they >>> are available for the SPI NOR, since u-boot is in there and the CPU then >>> accesses it. >>> >>> In an usual boot sequence, the SPI NOR is accessed first (copying u-boot to >>> the >>> RAM, reading out the environment) and so the pins are configured in >>> hardware at >>> boot time for accessing the SPI NOR. After that, they are configured to >>> access >>> the NAND where the kernel and filesystem are stored to boot Linux thanks to >>> env_relocate_spec() calling spi_flash_free() on exit in conjunction with [1] >>> >>> Now in the case where the boot sequence is interrupted and some accesses are >>> done to the SPI NOR, the pins are changed again to SPI NOR to perform these >>> accesses. But we have to make sure that the pins are configured back to >>> NAND by >>> calling spi_flash_free() after these accesses and that's why I introduced >>> the >>> release() function. >>> >>> In our case, there are 2 types of such accesses: >>> - environment variables write: this is the first patch of the series. It >>> simply >>> adds calls to spi_flash_free() at function exit no only in >>> env_relocate_spec() >>> but also in saveenv() so that the behavior here is coherent for the whole >>> env_sf >>> file (spi_flash_probe() at function start, spi_flash_free() at function >>> exit). >>> - updating u-boot: this is solved for us with the last 2 patches of the >>> series. >>> The first one just adds a sf release command that does the opposite/cleanup >>> to >>> sf probe and the second patch just calls this command in our scripts where >>> u-boot is updated/the SPI NOR is written. >>> >>> We are *indeed* using pin multiplexing changes, in our case, they are >>> implemented in the spi controller driver: drivers/spi/kirkwood_spi.c. To be >>> very >>> specific, in our case this sf release command allows to explicitely call >>> spi_flash_free() which calls spi_free_slave(), which in our case >>> (kirkwood_spi.c) sets the pins back to their previous configuration. >> >> 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. 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. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
