[PATCH 1/2] drm/tegra: Set DMA ops
acourbot at nvidia.com
Wed Feb 24 08:30:54 UTC 2016
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.
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