Best posts made by bazsi77

I don't get it, when issuing this command:

# perf_4.18 trace  --no-syscalls -e regmap:* cat /sys/devices/platform/unipi_plc/io_group2/di_2_16/di_value
0
     0.000 regmap:regmap_hw_read_start:spi0.2 reg=0 count=1
     0.215 regmap:regmap_hw_read_done:spi0.2 reg=0 count=1
     0.227 regmap:regmap_reg_read:spi0.2 reg=0 val=8000

I can see that regmap_reg_read() returned 0x8000, e.g. the MSB of the 16 bit register set, at least when the input is on. When turning off the voltage, the same says:

# perf_4.18 trace  --no-syscalls -e regmap:* cat /sys/devices/platform/unipi_plc/io_group2/di_2_16/di_value
0
     0.000 regmap:regmap_hw_read_start:spi0.2 reg=0 count=1
     0.215 regmap:regmap_hw_read_done:spi0.2 reg=0 count=1
     0.226 regmap:regmap_reg_read:spi0.2 reg=0 val=0

which means that the input was properly reported by the underlying hardware. The code that seemingly triggers this regmap_reg_read() is as follows:

static ssize_t neuronspi_spi_gpio_di_show_value(struct device *dev, struct device_attribute *attr, char *buf)
{
        # ... setup code deleted ...
            
        int val;

        # ... setup code deleted ...
        if (n_spi && n_spi->combination_id != 0xFF && n_spi->features && n_spi->features->di_count > n_di->io_index) {
                regmap_read(n_spi->reg_map, n_spi->regstart_table->di_val_reg + (n_di->io_index / 16), &val);
                val &= 0x1 << (n_di->io_index % 15);
                val = val >> (n_di->io_index % 15);
                ret = scnprintf(buf, 255, "%d\n", val);
        }
        return ret;
}

I originally wanted to write that I can't see the issue, but I just realized:

The remainder function is using modulo 15 instead of 16. The io_index is of course 15 for di_2_16, which will result in "0" to be used, thus di_2_16 would yield the input value of the first input, that is di_2_01. Let me check.

Bingo, results with di_2_01 set:

root@L203-sn190:/usr/src/unipi-1.32/unipi/src# perf_4.18 trace  --no-syscalls -e regmap:* cat /sys/devices/platform/unipi_plc/io_group2/di_2_16/di_value 
1
     0.000 regmap:regmap_hw_read_start:spi0.2 reg=0 count=1
     0.199 regmap:regmap_hw_read_done:spi0.2 reg=0 count=1
     0.208 regmap:regmap_reg_read:spi0.2 reg=0 val=1