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staging: comedi: comedi_isadma: Use a non-NULL device for DMA API 

The "comedi_isadma" module calls `dma_alloc_coherent()` and
`dma_free_coherent()` with a NULL device pointer which is no longer
allowed.  If the `hw_dev` member of the `struct comedi_device` has been
set to a valid device, that can be used instead.  Unfortunately, all the
current users of the "comedi_isadma" module leave the `hw_dev` member
set to NULL.  In that case, fall back to using the comedi "class" device
pointed to by the `class_dev` member if that is non-NULL.  In that case,
make it "DMA-capable" with a coherent DMA mask set to the ISA bus limit
of 16MB (24 bits).

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2019-04-26 14:54:13 +01:00 committed by Greg Kroah-Hartman
parent 575d927c42
commit a4965d98b4
2 changed files with 18 additions and 2 deletions
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17
drivers/staging/comedi/drivers/comedi_isadma.c
View File

@ -172,6 +172,19 @@ struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
goto no_dma;
dma->desc = desc;
dma->n_desc = n_desc;
if (dev->hw_dev) {
dma->dev = dev->hw_dev;
} else {
/* Fall back to using the "class" device. */
if (!dev->class_dev)
goto no_dma;
/* Need 24-bit mask for ISA DMA. */
if (dma_coerce_mask_and_coherent(dev->class_dev,
DMA_BIT_MASK(24))) {
goto no_dma;
}
dma->dev = dev->class_dev;
}
dma_chans[0] = dma_chan1;
if (dma_chan2 == 0 || dma_chan2 == dma_chan1)
@ -192,7 +205,7 @@ struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
desc = &dma->desc[i];
desc->chan = dma_chans[i];
desc->maxsize = maxsize;
desc->virt_addr = dma_alloc_coherent(NULL, desc->maxsize,
desc->virt_addr = dma_alloc_coherent(dma->dev, desc->maxsize,
&desc->hw_addr,
GFP_KERNEL);
if (!desc->virt_addr)
@ -224,7 +237,7 @@ void comedi_isadma_free(struct comedi_isadma *dma)
for (i = 0; i < dma->n_desc; i++) {
desc = &dma->desc[i];
if (desc->virt_addr)
dma_free_coherent(NULL, desc->maxsize,
dma_free_coherent(dma->dev, desc->maxsize,
desc->virt_addr,
desc->hw_addr);
}

3
drivers/staging/comedi/drivers/comedi_isadma.h
View File

@ -10,6 +10,7 @@
#include <linux/types.h>
struct comedi_device;
struct device;
/*
* These are used to avoid issues when <asm/dma.h> and the DMA_MODE_
@ -38,6 +39,7 @@ struct comedi_isadma_desc {
/**
* struct comedi_isadma - ISA DMA data
* @dev: device to allocate non-coherent memory for
* @desc: cookie for each DMA buffer
* @n_desc: the number of cookies
* @cur_dma: the current cookie in use
@ -45,6 +47,7 @@ struct comedi_isadma_desc {
* @chan2: the second DMA channel requested
*/
struct comedi_isadma {
struct device *dev;
struct comedi_isadma_desc *desc;
int n_desc;
int cur_dma;