On 07/30/13 20:55, Lo wrote: > Hello, > > using the iio driver framework I wrote a driver for an eight channel ADC, connected via SPI and a interrupt line. > In polling mode (reading /sys/bus/iio/..../in_voltageX_raw) everything works fine, but this access is obviously not way > I'd want to use to read lots of data. > Looking at other drivers (in staging/ kernel v3.2) I think the most appropriate way is to use the provided sw ring > buffer ring_sw.c > I'm not sure if my ring setup is correct, can someone please comment on this? > > My _probe function does the basic setup, inits a waitqueue and requests the irq line (a gpio): > iio->buffer = iio_sw_rb_allocate(iio); > iio->buffer->access = &ring_sw_access_funcs; > iio->pollfunc = iio_alloc_pollfunc(&iio_pollfunc_store_time, > &my_poll_handler, > IRQF_ONESHOT, //<-not sure about this flag > iio, > "my_consumer%d",//<-where is this for? Naming for the interrupt. Basically this is a variable number of arguements function so you can roll in creating the naming string with this call (in this case the iio->id is the only additional arguement afte the formatting. > iio->id); > iio->buffer->setup_ops = &my_ring_setup_ops; > iio->modes |= INDIO_BUFFER_TRIGGERED;//<-correct mode? yes > > Where my access funcs are: > .preenable = &my_buffer_preenable, > .postenable = &iio_triggered_buffer_postenable, > .predisable = &iio_triggered_buffer_predisable, > .postdisable = &my_buffer_postdisable > where: > preenable just sets iio->buffer->access->set_bytes_per_datum(iio->buffer, 19); The kfifo always contains aligned data. Hence it will be padded to the largest sized element. The only way it would correctly be 19 would be to have 19 8 bit or lower channels. Seems unlikely. Also why doesn't the generic function work for your case? > and enables the irq > postenable disables the irq > > My irq handler does basically this: > disable_irq_nosync(irq); Don't think you should need this if using the ONESHOT flag as it should be masked until handled. It's late here though so I might be completly wrong :) > iio_trigger_poll(adc->trig, iio_get_time_ns()); > return IRQ_HANDLED; > > My poll handler does this: > ring->access->store_to(ring, (u8 *)data, pf->timestamp); > iio_trigger_notify_done(iio->trig); > enable_irq(adc->spi->irq); > return IRQ_HANDLED; Looks fine. > > Is the approach of using the sw ring and the interrupt & poll_func more or less correct? > I've read ring.txt but still I get most of my kernel panics somewhere in ring of buffer management, so I must be doing > something wrong there. > Is any (simple) driver recommended as reference? I see different approaches in different drivers and I can't test them. Take a look at the dummy driver (still in drivers/staging/iio) as that can be tested without any hardware. (iio_simple_dummy > > --Lo > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
