On Sat, Nov 19, 2016 at 6:04 PM, Simon Glass <s...@chromium.org> wrote:
>> EPROTONOSUPPORT means: /* Protocol not supported */, which does not
>> seem to be very appropriate here.
>
> This is a protocol as far as I can see - you can either use one pin or
> four pins.
Actually they are SPI modes: one, two or four pins.
>> Why not return -EINVAL instead?
>
> The value is valid but is not supported. If we just return -EINVAL for
> anything we don't like, it makes it harder to root-cause the error. In
> particular we use -EINVAL when decoding the device tree. But
> EPROTONOSUPPORT is not widely used.
I think the current behaviour of not returning an error code on an
invalid mode is correct and it matches what the kernel does in
drivers/spi/spi.c.
If an invalid mode is passed we just ignore it and operate in single
mode instead.
Maybe we can make this clearer by printing a message like this:
--- a/drivers/spi/spi-uclass.c
+++ b/drivers/spi/spi-uclass.c
@@ -408,7 +408,7 @@ int spi_slave_ofdata_to_platdata(const void *blob, int node,
mode |= SPI_TX_QUAD;
break;
default:
- error("spi-tx-bus-width %d not supported\n", value);
+ printf("spi-tx-bus-width %d not supported, operating
in single mode\n", value);
break;
}
@@ -423,7 +423,7 @@ int spi_slave_ofdata_to_platdata(const void *blob, int node,
mode |= SPI_RX_QUAD;
break;
default:
- error("spi-rx-bus-width %d not supported\n", value);
+ printf("spi-rx-bus-width %d not supported, operating
in single mode\n", value);
break;
}
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