Messages in this thread Patch in this message | | | From | Charles Keepax <> | Subject | [PATCH] mfd: arizona: Don't use regmap_read_poll_timeout | Date | Fri, 11 May 2018 14:50:30 +0100 |
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Some Arizona CODECs have a small timing window where they will NAK an I2C transaction if it happens before the boot done bit is set. This can cause the read of the register containing the boot done bit to fail until it is set. Since regmap_read_poll_timeout will abort polling if a read fails it can't be reliably used to poll the boot done bit over I2C.
Do a partial revert of ef84f885e037 ("mfd: arizona: Refactor arizona_poll_reg"), removing the regmap_read_poll_timeout but leaving the refactoring to make the arizona_poll_reg take more sensible arguments.
Fixes: ef84f885e037 ("mfd: arizona: Refactor arizona_poll_reg") Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com> --- drivers/mfd/arizona-core.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c index 83f1c5a516d9..2ed29ce08dac 100644 --- a/drivers/mfd/arizona-core.c +++ b/drivers/mfd/arizona-core.c @@ -240,18 +240,31 @@ static int arizona_poll_reg(struct arizona *arizona, int timeout_ms, unsigned int reg, unsigned int mask, unsigned int target) { + ktime_t timeout = ktime_add_us(ktime_get(), timeout_ms * 1000); unsigned int val = 0; int ret; - ret = regmap_read_poll_timeout(arizona->regmap, - reg, val, ((val & mask) == target), - ARIZONA_REG_POLL_DELAY_US, - timeout_ms * 1000); - if (ret) - dev_err(arizona->dev, "Polling reg 0x%x timed out: %x\n", - reg, val); + while (true) { + ret = regmap_read(arizona->regmap, reg, &val); - return ret; + if ((val & mask) == target) + return 0; + + if (ktime_compare(ktime_get(), timeout) > 0) + break; + + usleep_range(ARIZONA_REG_POLL_DELAY_US / 2, + ARIZONA_REG_POLL_DELAY_US); + } + + if (ret) { + dev_err(arizona->dev, "Failed polling reg 0x%x: %d\n", + reg, ret); + return ret; + } + + dev_err(arizona->dev, "Polling reg 0x%x timed out: %x\n", reg, val); + return -ETIMEDOUT; } static int arizona_wait_for_boot(struct arizona *arizona) -- 2.11.0
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