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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 /drivers/usb/renesas_usbhs
parent0709831a50d31b3caf2237e8d7fe89e15b0d919d (diff)
downloadlinux-7b81cb6bddd2c4f2489506771070924bd0ae9902.tar.gz
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/renesas_usbhs')
-rw-r--r--drivers/usb/renesas_usbhs/mod_host.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/renesas_usbhs/mod_host.c b/drivers/usb/renesas_usbhs/mod_host.c
index ddd3be48f948..ae54221011c3 100644
--- a/drivers/usb/renesas_usbhs/mod_host.c
+++ b/drivers/usb/renesas_usbhs/mod_host.c
@@ -1283,7 +1283,7 @@ static const struct hc_driver usbhsh_driver = {
 	/*
 	 * generic hardware linkage
 	 */
-	.flags =		HCD_USB2,
+	.flags =		HCD_DMA | HCD_USB2,
 
 	.start =		usbhsh_host_start,
 	.stop =			usbhsh_host_stop,