The last parameter of `__get_free_pages()` is log2 (the 'order') of the
number of pages to be allocated. This driver seems to think it is the
linear number of pages, so `apci3120_auto_attach()` first tries to allocate
16 pages, but only uses 4 of them, setting the buffer size to PAGE_SIZE
multiplied by the 'order'. If the allocation fails, it tries
progressively smaller orders, down to 0. If the allocation at order 0
succeeds, the buffer size is set to 0, which is likely to cause
problems.
Set the buffer size to `PAGE_SIZE` shifted left by the allocation order.
Since the maximum buffer size previously used was 4, start with an
allocation order of 2 instead of 4. Rename the `ui_DmaBufferPages` member of
`struct addi_private` to `ui_DmaBufferPageOrder` and rename the `pages`
local variable to `order` to make it clearer what it is.
Note: `struct addi_private` is used by some other ADDI-DATA drivers as
well, but this is the only one using the affected members.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/addi-data/addi_common.h | 2 +-
drivers/staging/comedi/drivers/addi_apci_3120.c | 14 +++++++-------
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/staging/comedi/drivers/addi-data/addi_common.h b/drivers/staging/comedi/drivers/addi-data/addi_common.h
index a7400a2..88295e4 100644
--- a/drivers/staging/comedi/drivers/addi-data/addi_common.h
+++ b/drivers/staging/comedi/drivers/addi-data/addi_common.h
@@ -110,7 +110,7 @@ struct addi_private {
unsigned int ul_DmaBufferHw[2]; /* hw address of DMA buff */
unsigned int ui_DmaBufferSize[2]; /* size of dma buffer in bytes */
unsigned int ui_DmaBufferUsesize[2]; /* which size we may now used for transfer */
- unsigned int ui_DmaBufferPages[2]; /* number of pages in buffer */
+ unsigned int ui_DmaBufferPageOrder[2]; /* log2 of pages in buffer */
unsigned char b_DigitalOutputRegister; /* Digital Output Register */
unsigned char b_OutputMemoryStatus;
unsigned char b_TimerSelectMode; /* Contain data written at iobase + 0C */
diff --git a/drivers/staging/comedi/drivers/addi_apci_3120.c b/drivers/staging/comedi/drivers/addi_apci_3120.c
index 2ac95ba..57c36ed 100644
--- a/drivers/staging/comedi/drivers/addi_apci_3120.c
+++ b/drivers/staging/comedi/drivers/addi_apci_3120.c
@@ -57,7 +57,7 @@ static int apci3120_auto_attach(struct comedi_device *dev,
const struct addi_board *this_board = NULL;
struct addi_private *devpriv;
struct comedi_subdevice *s;
- int ret, pages, i;
+ int ret, order, i;
if (context < ARRAY_SIZE(apci3120_boardtypes))
this_board = &apci3120_boardtypes[context];
@@ -93,17 +93,17 @@ static int apci3120_auto_attach(struct comedi_device *dev,
/* Allocate DMA buffers */
devpriv->b_DmaDoubleBuffer = 0;
for (i = 0; i < 2; i++) {
- for (pages = 4; pages >= 0; pages--) {
+ for (order = 2; order >= 0; order--) {
devpriv->ul_DmaBufferVirtual[i] =
- (void *) __get_free_pages(GFP_KERNEL, pages);
+ (void *)__get_free_pages(GFP_KERNEL, order);
if (devpriv->ul_DmaBufferVirtual[i])
break;
}
if (!devpriv->ul_DmaBufferVirtual[i])
break;
- devpriv->ui_DmaBufferPages[i] = pages;
- devpriv->ui_DmaBufferSize[i] = PAGE_SIZE * pages;
+ devpriv->ui_DmaBufferPageOrder[i] = order;
+ devpriv->ui_DmaBufferSize[i] = PAGE_SIZE << order;
devpriv->ul_DmaBufferHw[i] =
virt_to_bus(devpriv->ul_DmaBufferVirtual[i]);
}
@@ -201,12 +201,12 @@ static void apci3120_detach(struct comedi_device *dev)
if (devpriv->ul_DmaBufferVirtual[0]) {
free_pages((unsigned long)devpriv->
ul_DmaBufferVirtual[0],
- devpriv->ui_DmaBufferPages[0]);
+ devpriv->ui_DmaBufferPageOrder[0]);
}
if (devpriv->ul_DmaBufferVirtual[1]) {
free_pages((unsigned long)devpriv->
ul_DmaBufferVirtual[1],
- devpriv->ui_DmaBufferPages[1]);
+ devpriv->ui_DmaBufferPageOrder[1]);
}
}
}
--
2.1.0
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
