It isn't safe to read the device ID in the SOFTWARE_RESET register until the silicon boot sequence has completed. This patch rearranges the code to wait until BOOT_DONE is set.
If we don't have a hard reset line we want to defer writing a soft reset command until we have identified the silicon as something we recognize. As the BOOT_DONE bit is sticky it is safe to wait for it without issuing a soft reset first, because the most recent power-up will have caused a boot sequence and set the bit. Note that the boot sequence is not the same as a reset so we still have to soft reset to get the codec into a known state. Signed-off-by: Stuart Henderson <[email protected]> Signed-off-by: Richard Fitzgerald <[email protected]> --- drivers/mfd/madera-core.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c index 1dedfe68a3dc..e114ca5e6c3f 100644 --- a/drivers/mfd/madera-core.c +++ b/drivers/mfd/madera-core.c @@ -455,10 +455,13 @@ int madera_dev_init(struct madera *madera) regcache_cache_only(madera->regmap, false); regcache_cache_only(madera->regmap_32bit, false); - /* - * Now we can power up and verify that this is a chip we know about - * before we start doing any writes to its registers. - */ + /* BOOT_DONE must be set before we can read 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); @@ -528,12 +531,13 @@ int madera_dev_init(struct madera *madera) 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 = madera_wait_for_boot(madera); + if (ret) { + dev_err(madera->dev, "Device failed initial soft reboot: %d\n", + ret); + goto err_reset; + } } ret = regmap_read(madera->regmap, MADERA_HARDWARE_REVISION, -- 2.11.0
