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authorChristoph Hellwig <hch@lst.de>2019-08-16 08:24:32 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-08-21 10:03:35 -0700
commit7b81cb6bddd2c4f2489506771070924bd0ae9902 (patch)
treee93409bd98a306bc26cc19c1c6a29f70029d42a0 /include/linux/usb.h
parent0709831a50d31b3caf2237e8d7fe89e15b0d919d (diff)
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.h1
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?