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authorChristoph Hellwig <hch@lst.de>2020-09-10 18:03:49 +0200
committerChristoph Hellwig <hch@lst.de>2020-09-17 18:43:25 +0200
commit6eb0233ec2d0df288fe8515d5b0b2b15562e05bb (patch)
treec1783ef708221981298dc653bbaa7db2c851e1cb /drivers/of/unittest.c
parentARM/keystone: move the DMA offset handling under ifdef CONFIG_ARM_LPAE (diff)
downloadlinux-6eb0233ec2d0df288fe8515d5b0b2b15562e05bb.tar.xz
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usb: don't inherity DMA properties for USB devices
As the comment in usb_alloc_dev correctly states, drivers can't use the DMA API on usb device, and at least calling dma_set_mask on them is highly dangerous. Unlike what the comment states upper level drivers also can't really use the presence of a dma mask to check for DMA support, as the dma_mask is set by default for most busses. Setting the dma_mask comes from "[PATCH] usbcore dma updates (and doc)" in BitKeeper times, as it seems like it was primarily for setting the NETIF_F_HIGHDMA flag in USB drivers, something that has long been fixed up since. Setting the dma_pfn_offset comes from commit b44bbc46a8bb ("usb: core: setup dma_pfn_offset for USB devices and, interfaces"), which worked around the fact that the scsi_calculate_bounce_limits functions wasn't going through the proper driver interface to query DMA information, but that function was removed in commit 21e07dba9fb1 ("scsi: reduce use of block bounce buffers") years ago. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/of/unittest.c')
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