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>
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 111787a..81afe55 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -5062,13 +5062,13 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
dwc2_hc_driver.reset_device = dwc2_reset_device;
}
+ if (hsotg->params.host_dma)
+ dwc2_hc_driver.flags |= HCD_DMA;
+
hcd = usb_create_hcd(&dwc2_hc_driver, hsotg->dev, dev_name(hsotg->dev));
if (!hcd)
goto error1;
- if (!hsotg->params.host_dma)
- hcd->self.uses_dma = 0;
-
hcd->has_tt = 1;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
