NothingOSS/android_kernel_msm-6.1_nothing_sm7635
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

staging: comedi: pcl816: fix short DMA transactions

Browse source 
When the cmd->stop_src == TRIG_COUNT the last DMA transfer might be smaller
than the buffer size. This results in invalid data being added to the async
buffer.

Add a 'size' member to the DMA descriptor and initialize it with the
actual size of the DMA transfer. Use that in interrupt and ai subdevice
(*poll) function to return the proper number of samples. Use the
comedi_bytes_to_samples() helper to convert the byte size to comedi
samples in the interrupt handler.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2015-01-12 10:56:04 -07:00 • committed by Greg Kroah-Hartman
parent a2c3966d18
commit ceb41be712
1 changed files with 18 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

34
drivers/staging/comedi/drivers/pcl816.c
View file

@ -116,6 +116,7 @@ static const struct pcl816_board boardtypes[] = {
struct pcl816_dma_desc {
void *virt_addr; /* virtual address of DMA buffer */
dma_addr_t hw_addr; /* hardware (bus) address of DMA buffer */
unsigned int size; /* transfer size (in bytes) */
};
struct pcl816_private {
@ -158,30 +159,30 @@ static void pcl816_ai_setup_dma(struct comedi_device *dev,
struct pcl816_dma_desc *dma = &devpriv->dma_desc[0];
struct comedi_cmd *cmd = &s->async->cmd;
unsigned int dma_flags;
unsigned int bytes;
bytes = devpriv->hwdmasize;
if (cmd->stop_src == TRIG_COUNT) {
/* how many */
bytes = cmd->stop_arg * comedi_bytes_per_scan(s);
dma->size = cmd->stop_arg * comedi_bytes_per_scan(s);
/* how many DMA pages we must fill */
devpriv->dma_runs_to_end = bytes / devpriv->hwdmasize;
devpriv->dma_runs_to_end = dma->size / devpriv->hwdmasize;
/* on last dma transfer must be moved */
devpriv->last_dma_run = bytes % devpriv->hwdmasize;
devpriv->last_dma_run = dma->size % devpriv->hwdmasize;
devpriv->dma_runs_to_end--;
if (devpriv->dma_runs_to_end >= 0)
bytes = devpriv->hwdmasize;
} else
dma->size = devpriv->hwdmasize;
} else {
dma->size = devpriv->hwdmasize;
devpriv->dma_runs_to_end = -1;
}
devpriv->cur_dma = 0;
set_dma_mode(devpriv->dma, DMA_MODE_READ);
dma_flags = claim_dma_lock();
clear_dma_ff(devpriv->dma);
set_dma_addr(devpriv->dma, dma->hw_addr);
set_dma_count(devpriv->dma, bytes);
set_dma_count(devpriv->dma, dma->size);
release_dma_lock(dma_flags);
enable_dma(devpriv->dma);
}
@ -199,13 +200,14 @@ static void pcl816_ai_setup_next_dma(struct comedi_device *dev,
/* switch dma bufs */
devpriv->cur_dma = 1 - devpriv->cur_dma;
dma = &devpriv->dma_desc[devpriv->cur_dma];
if (devpriv->dma_runs_to_end)
dma->size = devpriv->hwdmasize;
else
dma->size = devpriv->last_dma_run;
set_dma_mode(devpriv->dma, DMA_MODE_READ);
dma_flags = claim_dma_lock();
set_dma_addr(devpriv->dma, dma->hw_addr);
if (devpriv->dma_runs_to_end)
set_dma_count(devpriv->dma, devpriv->hwdmasize);
else
set_dma_count(devpriv->dma, devpriv->last_dma_run);
set_dma_count(devpriv->dma, dma->size);
release_dma_lock(dma_flags);
enable_dma(devpriv->dma);
}
@ -324,8 +326,8 @@ static irqreturn_t pcl816_interrupt(int irq, void *d)
struct comedi_subdevice *s = dev->read_subdev;
struct pcl816_private *devpriv = dev->private;
struct pcl816_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
unsigned int nsamples;
unsigned int bufptr;
unsigned int len;
if (!dev->attached || !devpriv->ai_cmd_running) {
pcl816_ai_clear_eoc(dev);
@ -340,11 +342,11 @@ static irqreturn_t pcl816_interrupt(int irq, void *d)
pcl816_ai_setup_next_dma(dev, s);
len = (devpriv->hwdmasize >> 1) - devpriv->ai_poll_ptr;
nsamples = comedi_bytes_to_samples(s, dma->size) - devpriv->ai_poll_ptr;
bufptr = devpriv->ai_poll_ptr;
devpriv->ai_poll_ptr = 0;
transfer_from_dma_buf(dev, s, dma->virt_addr, bufptr, len);
transfer_from_dma_buf(dev, s, dma->virt_addr, bufptr, nsamples);
pcl816_ai_clear_eoc(dev);
@ -542,7 +544,7 @@ static int pcl816_ai_poll(struct comedi_device *dev, struct comedi_subdevice *s)
}
/* where is now DMA in buffer */
top1 = devpriv->hwdmasize - top1;
top1 = dma->size - top1;
top1 >>= 1; /* sample position */
top2 = top1 - devpriv->ai_poll_ptr;
if (top2 < 1) { /* no new samples */