On 11/28/22 23:08, Billy Tsai wrote:
On 2022/11/23, 11:45 PM, "Guenter Roeck" <groeck7@xxxxxxxxx on behalf of linux@xxxxxxxxxxxx> wrote:
On 11/22/22 22:16, Billy Tsai wrote:
> > +The driver provides the following sensor accesses in sysfs:
> > +=============== ======= =====================================================
> > +fanX_input ro provide current fan rotation value in RPM as reported
> > + by the fan to the device.
> > +fanX_div rw Fan divisor: Supported value are power of 4 (1, 4, 16
> > + 64, ... 4194304)
> The code doesn't support 1.
The code can support 1.
Sorry, leftover from when I misread the code and thought it didn't.
> The existence of a status register makes me wonder what is in there.
> Does the controller report any errors ? If so, it might be worthwile
> adding attribute(s) for it.
> > + if (ret)
> > + return ret;
> > +
> > + if (!(val & TACH_ASPEED_FULL_MEASUREMENT))
> > + return 0;
> > + rpm = aspeed_tach_val_to_rpm(priv, fan_tach_ch,
> > + val & TACH_ASPEED_VALUE_MASK);
> > +
> > + return rpm;
The status register is the TACH_ASPEED_FULL_MEASUREMENT which is used to indicate that
the controller doesn't detect the change in tach pin for a long time.
> > +static void aspeed_create_fan_tach_channel(struct aspeed_tach_data *priv,
> > + u32 tach_ch)
> > +{
> > + priv->tach_present[tach_ch] = true;
> > + priv->tach_channel[tach_ch].limited_inverse = 0;
> > + regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
> > + TACH_ASPEED_INVERS_LIMIT,
> > + priv->tach_channel[tach_ch].limited_inverse ?
> > + TACH_ASPEED_INVERS_LIMIT :
> > + 0);
> > +
> What is the purpose of the above code ? limited_inverse is always 0.
> > + priv->tach_channel[tach_ch].tach_debounce = DEBOUNCE_3_CLK;
> > + regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
> > + TACH_ASPEED_DEBOUNCE_MASK,
> > + priv->tach_channel[tach_ch].tach_debounce
> > + << TACH_ASPEED_DEBOUNCE_BIT);
> > +
> > + priv->tach_channel[tach_ch].tach_edge = F2F_EDGES;
> > + regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
> > + TACH_ASPEED_IO_EDGE_MASK,
> > + priv->tach_channel[tach_ch].tach_edge
> > + << TACH_ASPEED_IO_EDGE_BIT);
> > +
> limited_inverse, tach_debounce, and tach_edge are constants.
> There is no need to keep constants as per-channel variables.
> > + priv->tach_channel[tach_ch].divisor = DEFAULT_TACH_DIV;
> > + regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
> > + TACH_ASPEED_CLK_DIV_T_MASK,
> > + DIV_TO_REG(priv->tach_channel[tach_ch].divisor)
> > + << TACH_ASPEED_CLK_DIV_BIT);
> > +
> > + priv->tach_channel[tach_ch].threshold = 0;
> > + regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
> > + TACH_ASPEED_THRESHOLD_MASK,
> > + priv->tach_channel[tach_ch].threshold);
> > +
> The above applies to threshold as well.
The above code is used to retain the adjustable feature of the controller.
I will remove them until I add the dts property to support them.
> > + }
> > +
> > + hwmon = devm_hwmon_device_register_with_info(dev, "aspeed_tach", priv,
> > + &aspeed_tach_chip_info, NULL);
> > + ret = PTR_ERR_OR_ZERO(hwmon);
> > + if (ret)
> > + return dev_err_probe(dev, ret,
> > + "Failed to register hwmon device\n");
> > + return 0;
> Why not return the error ? Either it is an error or it isn't. If it is
> not an error, dev_err_probe() is not appropriate. If it is, the error
> should be returned. Either case, if this is on purpose, it needs an
> explanation.
I have return the return value of the dev_err_probe. Did I miss someting?
No, me not having enough coffee when reviewing the code. Sorry for the noise.
Thanks,
Guenter
