diff options
| author | Christoph Hellwig <hch@lst.de> | 2020-09-10 18:03:49 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2020-09-17 18:43:25 +0200 |
| commit | 6eb0233ec2d0df288fe8515d5b0b2b15562e05bb (patch) | |
| tree | c1783ef708221981298dc653bbaa7db2c851e1cb /drivers/usb/core/message.c | |
| parent | cf141ae989e2ff119cd320326da5923b480d1641 (diff) | |
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/usb/core/message.c')
| -rw-r--r-- | drivers/usb/core/message.c | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 6197938dcc2d..9e45732dc1d1 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1954,12 +1954,6 @@ free_interfaces: intf->dev.bus = &usb_bus_type; intf->dev.type = &usb_if_device_type; intf->dev.groups = usb_interface_groups; - /* - * Please refer to usb_alloc_dev() to see why we set - * dma_mask and dma_pfn_offset. - */ - intf->dev.dma_mask = dev->dev.dma_mask; - intf->dev.dma_pfn_offset = dev->dev.dma_pfn_offset; INIT_WORK(&intf->reset_ws, __usb_queue_reset_device); intf->minor = -1; device_initialize(&intf->dev); |