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| author | Christoph Hellwig <hch@lst.de> | 2019-08-16 08:24:32 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-21 10:03:35 -0700 |
| commit | 7b81cb6bddd2c4f2489506771070924bd0ae9902 (patch) | |
| tree | e93409bd98a306bc26cc19c1c6a29f70029d42a0 /include/linux/usb.h | |
| parent | 0709831a50d31b3caf2237e8d7fe89e15b0d919d (diff) | |
| download | linux-7b81cb6bddd2c4f2489506771070924bd0ae9902.tar.gz linux-7b81cb6bddd2c4f2489506771070924bd0ae9902.tar.bz2 linux-7b81cb6bddd2c4f2489506771070924bd0ae9902.zip | |
usb: add a HCD_DMA flag instead of guestimating DMA capabilities
The usb core is the only major place in the kernel that checks for
a non-NULL device dma_mask to see if a device is DMA capable. This
is generally a bad idea, as all major busses always set up a DMA mask,
even if the device is not DMA capable - in fact bus layers like PCI
can't even know if a device is DMA capable at enumeration time. This
leads to lots of workaround in HCD drivers, and also prevented us from
setting up a DMA mask for platform devices by default last time we
tried.
Replace this guess with an explicit HCD_DMA that is set by drivers that
appear to have DMA support.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20190816062435.881-4-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/usb.h')
| -rw-r--r-- | include/linux/usb.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h index b548c530f988..e656e7b4b1e4 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -426,7 +426,6 @@ struct usb_bus { struct device *sysdev; /* as seen from firmware or bus */ int busnum; /* Bus number (in order of reg) */ const char *bus_name; /* stable id (PCI slot_name etc) */ - u8 uses_dma; /* Does the host controller use DMA? */ u8 uses_pio_for_control; /* * Does the host controller use PIO * for control transfers? |