From 34bd2f7b381e23c27c39d6d4ebe0069c360f119e Mon Sep 17 00:00:00 2001 From: Frank Mori Hess Date: Mon, 25 Jun 2001 22:36:16 +0000 Subject: [PATCH] I recently stumbled across an explanation of why you clear the dma flip-flop... --- comedi/drivers/das1800.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/comedi/drivers/das1800.c b/comedi/drivers/das1800.c index 3da830d3..99313bd2 100644 --- a/comedi/drivers/das1800.c +++ b/comedi/drivers/das1800.c @@ -657,12 +657,10 @@ static int das1800_attach(comedi_device *dev, comedi_devconfig *it) return -ENOMEM; flags = claim_dma_lock(); disable_dma(devpriv->dma0); - clear_dma_ff(devpriv->dma0); set_dma_mode(devpriv->dma0, DMA_MODE_READ); if(dma1) { disable_dma(devpriv->dma1); - clear_dma_ff(devpriv->dma1); set_dma_mode(devpriv->dma1, DMA_MODE_READ); } release_dma_lock(flags); @@ -930,6 +928,9 @@ static void das1800_handle_dma(comedi_device *dev, comedi_subdevice *s) flags = claim_dma_lock(); disable_dma(devpriv->dma_current); + /* clear flip-flop to make sure 2-byte registers for + * count and address get set correctly */ + clear_dma_ff(devpriv->dma_current); // figure out how many points to read maxPoints = devpriv->dma_buf_size / sizeof(short); @@ -1397,6 +1398,9 @@ void setup_dma(comedi_device *dev, comedi_cmd cmd) lock_flags = claim_dma_lock(); disable_dma(devpriv->dma0); + /* clear flip-flop to make sure 2-byte registers for + * count and address get set correctly */ + clear_dma_ff(devpriv->dma0); set_dma_addr(devpriv->dma0, (unsigned int) devpriv->dma_buf0); // set appropriate size of transfer if(devpriv->count * sizeof(short) >= devpriv->dma_buf_size || devpriv->forever) @@ -1407,6 +1411,9 @@ void setup_dma(comedi_device *dev, comedi_cmd cmd) if(dual_dma && (devpriv->count * sizeof(short) > devpriv->dma_buf_size || devpriv->forever)) { disable_dma(devpriv->dma1); + /* clear flip-flop to make sure 2-byte registers for + * count and address get set correctly */ + clear_dma_ff(devpriv->dma1); set_dma_addr(devpriv->dma1, (unsigned int) devpriv->dma_buf1); // set appropriate size of transfer if(devpriv->count * sizeof(short) >= 2 * devpriv->dma_buf_size || devpriv->forever) @@ -1452,7 +1459,8 @@ static int das1800_ai_do_cmd(comedi_device *dev, comedi_subdevice *s) { int ret; int control_a, control_c; - comedi_cmd cmd = s->async->cmd; + comedi_async *async = s->async; + comedi_cmd cmd = async->cmd; if(!dev->irq) { @@ -1508,6 +1516,7 @@ static int das1800_ai_do_cmd(comedi_device *dev, comedi_subdevice *s) return ret; } setup_dma(dev, cmd); + async->events = 0; outb(control_c, dev->iobase + DAS1800_CONTROL_C); // set conversion rate and length for burst mode if(control_c & BMDE) -- 2.26.2