Commits
Chen-Yu Tsai committed 696f0b3f4ae
mfd: axp20x: Fix AXP806 access errors on cold boot The AXP806 supports either master/standalone or slave mode. Slave mode allows sharing the serial bus, even with multiple AXP806 which all have the same hardware address. This is done with extra "serial interface address extension", or AXP806_BUS_ADDR_EXT, and "register address extension", or AXP806_REG_ADDR_EXT, registers. The former is read-only, with 1 bit customizable at the factory, and 1 bit depending on the state of an external pin. The latter is writable. Only when the these device addressing bits (in the upper 4 bits of the registers) match, will the device respond to operations on its other registers. The AXP806_REG_ADDR_EXT was previously configured by Allwinner's bootloader. Work on U-boot SPL support now allows us to switch to mainline U-boot, which doesn't do this for us. There might be other bare minimum bootloaders out there which don't to this either. It's best to handle this in the kernel. This patch sets AXP806_REG_ADDR_EXT to 0x10, which is what we know to be the proper value for a standard AXP806 in slave mode. Afterwards it will reinitialize the regmap cache, to purge any invalid stale values. Signed-off-by: Chen-Yu Tsai <wens@csie.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>