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. Valentin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
