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Commit a4965d98 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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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: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 575d927c

drivers/staging/comedi/drivers/comedi_isadma.c

+15 −2
Original line number Diff line number Diff line
@@ -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);

		}

drivers/staging/comedi/drivers/comedi_isadma.h

+3 −0
Original line number Diff line number Diff line
@@ -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;