Hi Guenter,
On 7/5/24 4:28 PM, Guenter Roeck wrote:
On 7/5/24 03:59, Quentin Schulz wrote:
Hi Guenter,
On 7/4/24 7:52 PM, Guenter Roeck wrote:
[...]
+ err = regmap_read(regmap,
+ channel ? AMC6821_REG_RTEMP_FAN_CTRL :
AMC6821_REG_LTEMP_FAN_CTRL,
+ ®val);
+ if (err)
+ return err;
+ temps[1] = (regval & 0xF8) >> 1;
I think we want to use AMC6821_TEMP_LIMIT_MASK here instead of 0xF8?
I guess we could also use FIELD_GET?
Yes. The value in the register is in °C * 4, so that is going to be
temps[1] = FIELD_GET(regval, AMC6821_TEMP_LIMIT_MASK) * 4;
which improves readability and should also clarify the units a bit
better.
Note hat
(regval & 0xF8) >> 1;
resulted in the temperature in °C (shift right 1 instead of 3).
Yes, it actually took me a while to figure out why this 1b shift was
necessary as it didn't match what I got from the datasheet, but the
formula was actually (>>3) * 4. Former because the register starts at
bit 3, so we need to right-shift by three bits to have the actual value.
Then multiply by 4 because a bit in the register means 4°C.
So yes, much more readable with this instead :)
[...]
+ /*
+ * Passive cooling temperature. Range limit against low limit
+ * of both channels.
+ */
+ val = DIV_ROUND_CLOSEST(clamp_val(val, 0, 63000), 1000);
This was already in the original code, but I think 64°C should be
doable as well? The datasheet says:
"""
The PSV ranges from 0°C to +64°C.
"""
Yes, but I am sure the datasheet is wrong here. The register has 6
active bits,
which means the highest possible value is 0x3f or 63.
And there's a PSV8 bit we can write, meaning we can do (1 << 8) with a
step of 4°C which gives us 64°C? In a separate commit though, to not
mix too many fixes into one, making it easier for people to identify
and possibly revert them if necessary.
Not sure I understand. Can you clarify ?
Temperature bit assignments in the datasheet are confusing. PSV3
means full degrees C, PSV8 means 32 degrees C. That is all in one register.
On the other side, L-TEMP0 reflects _4_ degrees C.
Am I missing something ?
No, my brain came up with its own math. Register value TEMPERATURE
MONITORING section all seems to be 1°C increments (except
Temp-DATA-LByte since it represents 0.125°C increments for a few select
registers.
Thanks for taking the time to explain!
Quentin
