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The ir-spi driver has 2 issues which prevents it from working with
lirc:
1. The ir-spi driver uses 16 bits of SPI data to create one cycle of
the waveform. As such our SPI clock needs to be 16x faster than the
carrier frequency.
The driver is inconsistent in how it currently handles this. It
initializes it to the carrier frequency:
But the commit message has some example code which initialises it
to 16x the carrier frequency:
val = 608000;
ret = ioctl(fd, LIRC_SET_SEND_CARRIER, &val);
To maintain compatibility with lirc, always do the frequency adjustment
in the driver.
2. lirc presents pulses in microseconds, but the ir-spi driver treats
them as cycles of the carrier. Similar to other lirc drivers, do the
conversion with DIV_ROUND_CLOSEST().
Fixes: fe052da49201 ("[media] rc: add support for IR LEDs driven through SPI")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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The ir-spi is a simple device driver which supports the
connection between an IR LED and the MOSI line of an SPI device.
The driver, indeed, uses the SPI framework to stream the raw data
provided by userspace through an rc character device. The chardev
is handled by the LIRC framework and its functionality basically
provides:
- write: the driver gets a pulse/space signal and translates it
to a binary signal that will be streamed to the IR led through
the SPI framework.
- set frequency: sets the frequency whith which the data should
be sent. This is handle with ioctl with the
LIRC_SET_SEND_CARRIER flag (as per lirc documentation)
- set duty cycle: this is also handled with ioctl with the
LIRC_SET_SEND_DUTY_CYCLE flag. The driver handles duty cycles
of 50%, 60%, 70%, 75%, 80% and 90%, calculated on 16bit data.
The character device is created under /dev/lircX name, where X is
and ID assigned by the LIRC framework.
Example of usage:
fd = open("/dev/lirc0", O_RDWR);
if (fd < 0)
return -1;
val = 608000;
ret = ioctl(fd, LIRC_SET_SEND_CARRIER, &val);
if (ret < 0)
return -1;
val = 60;
ret = ioctl(fd, LIRC_SET_SEND_DUTY_CYCLE, &val);
if (ret < 0)
return -1;
n = write(fd, buffer, BUF_LEN);
if (n < 0 || n != BUF_LEN)
ret = -1;
close(fd);
Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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