From 7b81cb6bddd2c4f2489506771070924bd0ae9902 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 16 Aug 2019 08:24:32 +0200 Subject: 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 Link: https://lore.kernel.org/r/20190816062435.881-4-hch@lst.de Signed-off-by: Greg Kroah-Hartman --- include/linux/usb/hcd.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'include/linux/usb') 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, -- cgit v1.2.3-59-g8ed1b