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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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christoph Hellwig 2018-04-27 09:02:55 +02:00
parent 884571f0de
commit f068fe3170
2 changed files with 9 additions and 0 deletions
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3
include/linux/device.h
View File

@ -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)

6
lib/dma-direct.c
View File

@ -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;
}