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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 /drivers/usb/host/ehci-ppc-of.c | |
| parent | 0709831a50d31b3caf2237e8d7fe89e15b0d919d (diff) | |
| download | lwn-7b81cb6bddd2c4f2489506771070924bd0ae9902.tar.gz lwn-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 'drivers/usb/host/ehci-ppc-of.c')
| -rw-r--r-- | drivers/usb/host/ehci-ppc-of.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/ehci-ppc-of.c b/drivers/usb/host/ehci-ppc-of.c index 576f7d79ad4e..6bbaee74f7e7 100644 --- a/drivers/usb/host/ehci-ppc-of.c +++ b/drivers/usb/host/ehci-ppc-of.c @@ -31,7 +31,7 @@ static const struct hc_driver ehci_ppc_of_hc_driver = { * generic hardware linkage */ .irq = ehci_irq, - .flags = HCD_MEMORY | HCD_USB2 | HCD_BH, + .flags = HCD_MEMORY | HCD_DMA | HCD_USB2 | HCD_BH, /* * basic lifecycle operations |