Re: [spi-devel-general] [PATCH 2/3] [SPI] Add new mode: SPI_LOOP
From: David Brownell <hidden>
Date: 2007-07-27 03:15:03
Also in:
linux-spi
On Thursday 26 July 2007, Anton Vorontsov wrote:
Loopback mode is supported by various controllers, this mode is useful for testing, especially in conjunction with spidev driver.
ISTR that Stephen Street provided a loopback mode for debug in his pxa2xx_spi code. And I know you're fight that this mode shows up in a lot of hardware. Comments, anyone? This seems like a fair way to expose this mechanism. And I tend to agree that it'd mostly be useful in conjunction with "spidev". Anton -- assuming this goes in, it'd be nice if you could contribute a simple test program using this, which we could keep in Documentation/spi somewhere. (Maybe with other testing notes, if anyone comes up with such.) - Dave
quoted hunk ↗ jump to hunk
...--- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h@@ -77,6 +77,7 @@ struct spi_device { #define SPI_CS_HIGH 0x04 /* chipselect active high? */ #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ #define SPI_3WIRE 0x10 /* SI/SO signals shared */ +#define SPI_LOOP 0x20 /* loopback mode */ u8 bits_per_word; int irq; void *controller_state;