Re: [PATCH v2 1/5] iio: adc: mcp320x: use callbacks for RX conversion

From: Andy Shevchenko
Date: Wed Aug 31 2022 - 08:41:45 EST


On Wed, Aug 31, 2022 at 1:05 PM Vincent Whitchurch
<vincent.whitchurch@xxxxxxxx> wrote:
>
> Replace the device_index switch with callbacks from the chip_info
> structure, so that the latter has all the information needed to handle
> the variants.

Below are for the further patches, as I see the original code has the
same disadvantages.

...

> struct mcp320x_chip_info {
> const struct iio_chan_spec *channels;
> unsigned int num_channels;
> unsigned int resolution;

> unsigned int conv_time; /* usec */

Instead of a comment, I would rename it to conv_time_us.

> + int (*convert_rx)(struct mcp320x *adc);
> };

...

> + return adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3;

> + return adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6;

> + return adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1;

> + return adc->rx_buf[0] << 4 | adc->rx_buf[1] >> 4;

> + return sign_extend32((adc->rx_buf[0] & 0x1f) << 8 | adc->rx_buf[1], 12);

All above should really use

u16 buf = be16_to_cpu(&adc->rx_buf[0]);

return buf >> 3 /* 6, 1, 4 (respectively) */;

...

> + if (raw & BIT(22) && raw & BIT(23))

> + return -EIO; /* cannot have overrange AND underrange */
> + else if (raw & BIT(22))

Redundant 'else'.

> + raw &= ~BIT(22); /* overrange */
> + else if (raw & BIT(23) || raw & BIT(21))

if (raw & (BIT(23) | BIT(21))) ?

> + raw |= GENMASK(31, 22); /* underrange or negative */

...

> [mcp3201] = {
> .channels = mcp3201_channels,
> .num_channels = ARRAY_SIZE(mcp3201_channels),
> + .convert_rx = mcp3201_convert_rx,

> .resolution = 12

+ Comma in such lines.

> },

--
With Best Regards,
Andy Shevchenko