It isn't safe to read the device ID in SOFTWARE_RESET register until the silicon boot sequence has completed. This patch rearranges the code to wait for BOOT_DONE first.
If we don't have a GPIO to control hard reset we must issue a soft reset to get the silicon into a known-good booted state before reading the device ID. Signed-off-by: Stuart Henderson <[email protected]> Signed-off-by: Richard Fitzgerald <[email protected]> --- drivers/mfd/madera-core.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c index 3ff9a0615658..b9d42edf96c9 100644 --- a/drivers/mfd/madera-core.c +++ b/drivers/mfd/madera-core.c @@ -454,10 +454,23 @@ int madera_dev_init(struct madera *madera) regcache_cache_only(madera->regmap, false); regcache_cache_only(madera->regmap_32bit, false); + /* If we don't have a reset GPIO use a soft reset */ + if (!madera->pdata.reset) { + ret = madera_soft_reset(madera); + if (ret) + goto err_reset; + } + /* - * Now we can power up and verify that this is a chip we know about - * before we start doing any writes to its registers. + * Must wait for internal boot sequence to complete before + * reading the device ID */ + ret = madera_wait_for_boot(madera); + if (ret) { + dev_err(madera->dev, "Device failed initial boot: %d\n", ret); + goto err_reset; + } + ret = regmap_read(madera->regmap, MADERA_SOFTWARE_RESET, &hwid); if (ret) { dev_err(dev, "Failed to read ID register: %d\n", ret); @@ -519,22 +532,6 @@ int madera_dev_init(struct madera *madera) goto err_reset; } - /* - * It looks like a device we support. If we don't have a hard reset - * we can now attempt a soft reset. - */ - if (!madera->pdata.reset) { - ret = madera_soft_reset(madera); - if (ret) - goto err_reset; - } - - ret = madera_wait_for_boot(madera); - if (ret) { - dev_err(madera->dev, "Device failed initial boot: %d\n", ret); - goto err_reset; - } - ret = regmap_read(madera->regmap, MADERA_HARDWARE_REVISION, &madera->rev); if (ret) { -- 2.11.0
