Commit f068fe31 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

core, dma-direct: add a flag 32-bit dma limits 



Various PCI bridges (VIA PCI, Xilinx PCIe) limit DMA to only 32-bits
even if the device itself supports more.  Add a single bit flag to
struct device (to be moved into the dma extension once we get to it)
to flag such devices and reject larger DMA to them.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 884571f0

include/linux/device.h

+3 −0
Original line number Diff line number Diff line
@@ -904,6 +904,8 @@ struct dev_links_info { 
 * @offline:	Set after successful invocation of bus type's .offline().

 * @of_node_reused: Set if the device-tree node is shared with an ancestor

 *              device.

 * @dma_32bit_limit: bridge limited to 32bit DMA even if the device itself

 *		indicates support for a higher limit in the dma_mask field.

 *

 * At the lowest level, every device in a Linux system is represented by an

 * instance of struct device. The device structure contains the information
@@ -992,6 +994,7 @@ struct device { 
	bool			offline_disabled:1;

	bool			offline:1;

	bool			of_node_reused:1;

	bool			dma_32bit_limit:1;

};



static inline struct device *kobj_to_dev(struct kobject *kobj)

lib/dma-direct.c

+6 −0
Original line number Diff line number Diff line
@@ -172,6 +172,12 @@ int dma_direct_supported(struct device *dev, u64 mask) 
	if (mask < DMA_BIT_MASK(32))

		return 0;

#endif

	/*

	 * Various PCI/PCIe bridges have broken support for > 32bit DMA even

	 * if the device itself might support it.

	 */

	if (dev->dma_32bit_limit && mask > DMA_BIT_MASK(32))

		return 0;

	return 1;

}