On 09/23/2015 01:57 PM, Peter Rosin wrote:
[...]
Looks pretty good.
One thing I'm concerned about is that this array
> +static const struct mcp4531_cfg mcp4531_cfg[] = {
> + { /* MCP4531-502 */ .wipers = 1, .max_pos = 128, .kohms = 5, },
> + { /* MCP4531-103 */ .wipers = 1, .max_pos = 128, .kohms = 10, },
> + { /* MCP4531-503 */ .wipers = 1, .max_pos = 128, .kohms = 50, },
> + { /* MCP4531-104 */ .wipers = 1, .max_pos = 128, .kohms = 100, },
[...]
> +};
> +
And the indices into the array defined here need to stay in sync. It is
really easy to mess this up by accident when a new entry is added. And it
will probably take a while to notice when this happens.
> +static const struct i2c_device_id mcp4531_id[] = {
> + { "mcp4531-502", 0 },
> + { "mcp4531-103", 1 },
> + { "mcp4531-503", 2 },
> + { "mcp4531-104", 3 },
[...]
> + {}
> +};
I see two options to solve this. Either define a enum with all the different
devices and use a symbolic name for the indices.
E.g.
enum mcp4531_type {
MCP4531_502,
MCP4531_103,
...
};
static const struct mcp5431_cfg mcp5431_cfg[] = {
[MCP4531_502] = {.wipers = 1, .max_pos = 128, .kohms = 5, },
[MCP4531_103] = {.wipers = 1, .max_pos = 128, .kohms = 10, },
...
};
static const struct i2c_device_id mcp4531_id[] = {
{ "mcp4531-502", MCP4531_502 },
{ "mcp4531-103", MCP4531_103 },
...
};
Or the second option is to directly assign the cfg struct as the driver data
in the device ID table.
E.g.
#define MCP4531_CFG(_wipers, _max_pos, _kohms) \
(kernel_ulong_t)&(struct mcp4531_cfg) { \
.wipers = _wipers, .max_pos = _max_pos, .kohms = _kohms }
static const struct i2c_device_id mcp4531_id[] = {
{ "mcp4531-502", MCP4531_CFG(1, 128, 5) },
{ "mcp4531-103", MCP4531_CFG(1, 128, 10) },
...
};
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