diff options
| author | Christoph Hellwig <hch@lst.de> | 2019-08-16 09:24:32 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-21 20:03:35 +0300 |
| commit | 7b81cb6bddd2c4f2489506771070924bd0ae9902 (patch) | |
| tree | e93409bd98a306bc26cc19c1c6a29f70029d42a0 /include/linux | |
| parent | 0709831a50d31b3caf2237e8d7fe89e15b0d919d (diff) | |
| download | linux-7b81cb6bddd2c4f2489506771070924bd0ae9902.tar.xz | |
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')
| -rw-r--r-- | include/linux/usb.h | 1 | ||||
| -rw-r--r-- | include/linux/usb/hcd.h | 7 |
2 files changed, 5 insertions, 3 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? diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h index a20e7815d814..8d3869c7de85 100644 --- a/include/linux/usb/hcd.h +++ b/include/linux/usb/hcd.h @@ -256,6 +256,7 @@ struct hc_driver { int flags; #define HCD_MEMORY 0x0001 /* HC regs use memory (else I/O) */ +#define HCD_DMA 0x0002 /* HC uses DMA */ #define HCD_SHARED 0x0004 /* Two (or more) usb_hcds share HW */ #define HCD_USB11 0x0010 /* USB 1.1 */ #define HCD_USB2 0x0020 /* USB 2.0 */ @@ -422,8 +423,10 @@ static inline bool hcd_periodic_completion_in_progress(struct usb_hcd *hcd, return hcd->high_prio_bh.completing_ep == ep; } -#define hcd_uses_dma(hcd) \ - (IS_ENABLED(CONFIG_HAS_DMA) && (hcd)->self.uses_dma) +static inline bool hcd_uses_dma(struct usb_hcd *hcd) +{ + return IS_ENABLED(CONFIG_HAS_DMA) && (hcd->driver->flags & HCD_DMA); +} extern int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd, struct urb *urb); extern int usb_hcd_check_unlink_urb(struct usb_hcd *hcd, struct urb *urb, |