Re: [PATCH 1/4] Introduce regmap infrastructure over Maxim/Dalas OneWire (W1) bus

From: Alex A. Mihaylov
Date: Fri May 26 2017 - 11:50:39 EST



This looks mostly fine, a couple of small things and like I said in
reply to Greg please use subject lines matching the style for the
subsystem - this makes it a lot easier for people to identify relevant
patches.

+ int ret = -ENODEV;
+
+
+ if (reg > 255)
+ return -EINVAL;
+
+ mutex_lock(&sl->master->bus_mutex);
+ if (!w1_reset_select_slave(sl)) {
+ w1_write_8(sl->master, W1_CMD_READ_DATA);
+ w1_write_8(sl->master, reg);
+ *val = w1_read_8(sl->master);
+ ret = 0;
+ }
+ mutex_unlock(&sl->master->bus_mutex);
This is a bit confusing with how -ENODEV is generated - move the
assignment into the if statement so it doesn't look like we're silently
ignoring errors unless you look back to the top of the function.
Ok. I set default return value to -ENODEV. W1 (OneWire) Bus periodically scan for connected devices. Typical time between scans about 60 sec. This period W1 slave device can present in kernel device list, but will physically disconnected.

Only w1_reset_select_slave(sl) can say me about device still physically accessible. Only on success w1_reset_select_slave return zero. I think code, like

if (!w1_reset_select_slave(sl)) {
[...]
ret =0;
} else
ret = -ENODEV;

not good.

+static struct regmap_bus regmap_w1_bus_a8_v16 = {
+ .reg_read = w1_reg_a8_v16_read,
+ .reg_write = w1_reg_a8_v16_write,
+};
It'd be clearer to just have all all these structs at the end of the set
of functions rather than scattered about randomly.
Ok. I move this structs down in next version of patches.

I hope that the next edition will not contain such a large number of registration errors. Sorry for all.