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SubjectRe: [PATCH 2/2] drivers: iio: accel adxl312 and adxl314 support
On Tue, 16 Aug 2022 14:16:13 +0300
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:

> On 16/08/2022 13:28, George Mois wrote:
> > ADXL312 and ADXL314 are small, thin, low power, 3-axis accelerometers
> > with high resolution (13-bit) measurement up to +/-12 g and +/- 200 g
> > respectively.
> >
>
> Thank you for your patch. There is something to discuss/improve.
>
> >
> > static const struct spi_device_id adxl313_spi_id[] = {
> > - { "adxl313" },
> > + { "adxl312", ADXL312 },
> > + { "adxl313", ADXL313 },
> > + { "adxl314", ADXL314 },
> > { }
> > };
> >
> > MODULE_DEVICE_TABLE(spi, adxl313_spi_id);
> >
> > static const struct of_device_id adxl313_of_match[] = {
> > + { .compatible = "adi,adxl312" },
> > { .compatible = "adi,adxl313" },
> > + { .compatible = "adi,adxl314" },
>
> You miss here driver data. I don't remember which driver matching takes
> precedence (especially in various cases like DT platforms with device
> instantiated by MFD), but for consistency I think both device id tables
> should have same driver data.

You can set it up to try device_get_match_data() first then fallback
to the adxl313_spi_id[] table but there isn't a nice 'standard' way to
do it.

If that isn't done, then IIRC the match is against the compatible with
the vendor ID dropped and the table used is the spi_device_id one.
Which is just annoyingly complex and relies on the strings matching.

In the ideal world the spi_device_id table would go away but there are
still a few users (greybus - I think + remaining board files).
So for now something like

a = device_get_match_data(dev);
if (!a)
a = &adxl31x_spi_regmap_config[id->data];

Provides a good way of ensuring the id tables don't need to remain
in sync.

Jonathan


>
>
> Best regards,
> Krzysztof

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