On 02/24/2016 12:28 AM, Thierry Reding wrote: > * PGP Signed by an unknown key > > On Tue, Feb 23, 2016 at 03:25:53PM +0900, Alexandre Courbot wrote: >> The current settings leaves the DRM device's dma_ops field NULL, which >> makes it use the dummy DMA ops on arm64 and return an error whenever we >> try to import a buffer. Call of_dma_configure() with a NULL node (since >> the device is not spawn from the device tree) so that >> arch_setup_dma_ops() is called and sets the default ioswtlb DMA ops. >> >> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com> >> --- >> drivers/gpu/drm/tegra/drm.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c >> index d347188bf8f4..bc0555adecaf 100644 >> --- a/drivers/gpu/drm/tegra/drm.c >> +++ b/drivers/gpu/drm/tegra/drm.c >> @@ -9,6 +9,7 @@ >> >> #include <linux/host1x.h> >> #include <linux/iommu.h> >> +#include <linux/of_device.h> >> >> #include <drm/drm_atomic.h> >> #include <drm/drm_atomic_helper.h> >> @@ -990,6 +991,7 @@ static int host1x_drm_probe(struct host1x_device *dev) >> return -ENOMEM; >> >> dev_set_drvdata(&dev->dev, drm); >> + of_dma_configure(drm->dev, NULL); > > Looking at the various pieces, I think this really belongs in > host1x_device_add() (see drivers/gpu/host1x/bus.c) where it can replace > the open-coded setting of DMA and coherent DMA masks. Also why can't we > pass the correct device tree node here? The DRM device is a virtual > device that hangs off the host1x device, so I think it could use the > same device tree node as the host1x device. > > Something like the below (untested).
You're right, that looks like a much better place to do this. of_dma_configure() is called at the bus level (platform and PCI), so it makes sense to do it from host1x too.
