Hi, On 24.04.2016 19:10, Pavel Machek wrote:
Hi!According to the TRM, we need to enable i2c access to powerbus before writing to it. Also, a new write to powerbus should not be attempted if there is a pending transfer. The current code does not implement that functionality and while there are no known problems caused by that, it is better to follow what TRM says. Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov...@gmail.com> --- drivers/regulator/twl-regulator.c | 78 +++++++++++++++++++++++++++++++++++---- 1 file changed, 70 insertions(+), 8 deletions(-) diff --git a/drivers/regulator/twl-regulator.c b/drivers/regulator/twl-regulator.c index 955a6fb..aad748b0 100644 --- a/drivers/regulator/twl-regulator.c +++ b/drivers/regulator/twl-regulator.c @@ -21,7 +21,7 @@ #include <linux/regulator/machine.h> #include <linux/regulator/of_regulator.h> #include <linux/i2c/twl.h> - +#include <linux/delay.h> /* * The TWL4030/TW5030/TPS659x0/TWL6030 family chips include power management, a @@ -188,6 +188,74 @@ static int twl6030reg_is_enabled(struct regulator_dev *rdev) return grp && (val == TWL6030_CFG_STATE_ON); } +#define PB_I2C_BUSY BIT(0) +#define PB_I2C_BWEN BIT(1) + +/* Wait until buffer empty/ready to send a word on power bus. */ +static int twl4030_wait_pb_ready(void) +{ + + int ret; + int timeout = 10; + u8 val; +Can we do this plain while (timeout--) { }...
Now looking at the code, yes, while(timeout--) looks prettier, but as the $subject patch is in the linux-next for a couple of weeks already, that change will need another patch. I'll put that in my TODO, right after the RFC for the N900 cameras :) .
? Also... if the bit is not immediately available, it will wait for 1msec. Would it make sense to have timeout = 1000 but wait only 10usec each time or something?
Well, anyway these look like a kind of arbitrary values, I guess it will work both ways. But, I borrowed the code in the patch from stock Nokia kernel, it has been field tested on tens of thousands of devices, so, unless you have hard values giving a reason to do it the other way, I prefer to keep it as it is.
Regards, Ivo
+ do { + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val, + TWL4030_PM_MASTER_PB_CFG); + if (ret < 0) + return ret; + + if (!(val & PB_I2C_BUSY)) + return 0; + + mdelay(1); + timeout--; + } while (timeout); + + return -ETIMEDOUT; +}
