From 5fc336c6101ec9cca37a062253c01c0429c44a16 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Mon, 1 Mar 2021 16:57:54 +0000 Subject: [PATCH] staging: comedi: dt2814: Call dt2814_ai_clear() during initialization The Comedi "attach" handler `dt2814_attach()` writes to the Control register to turn off the timer enable 'ENB' bit, which triggers a conversion. It then sleeps awhile and checks the Status register, returning an error if the ERR bit is set. However, the ERR bit could have been set due to the conversion being triggered while the A/D converter was busy (unlikely) or due to the conversion being triggered before some previous sample had been read from the A/D Data register. Replace the existing code with a call to `dt2814_ai_clear()` which waits for any conversion to finish and then clears any unread data or error condition. A non-zero return value from `dt2814_ai_clear()` indicates a time-out while waiting for the A/D converter to become non-busy. Return an error in that case. Signed-off-by: Ian Abbott Link: https://lore.kernel.org/r/20210301165757.243065-4-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/dt2814.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/staging/comedi/drivers/dt2814.c b/drivers/staging/comedi/drivers/dt2814.c index 8a70b7b..da4dc4d 100644 --- a/drivers/staging/comedi/drivers/dt2814.c +++ b/drivers/staging/comedi/drivers/dt2814.c @@ -262,13 +262,10 @@ static int dt2814_attach(struct comedi_device *dev, struct comedi_devconfig *it) return ret; outb(0, dev->iobase + DT2814_CSR); - usleep_range(100, 200); - if (inb(dev->iobase + DT2814_CSR) & DT2814_ERR) { + if (dt2814_ai_clear(dev)) { dev_err(dev->class_dev, "reset error (fatal)\n"); return -EIO; } - inb(dev->iobase + DT2814_DATA); - inb(dev->iobase + DT2814_DATA); if (it->options[1]) { ret = request_irq(it->options[1], dt2814_interrupt, 0, -- 2.7.4