Re: [PATCH] drm/tegra: Remove of_dma_configure() from host1x_device_add()

[Jon Hunter <jonathanh@nvidia.com>]

On 30/01/2024 16:15, Jason Gunthorpe wrote:
> This was added in commit c95469aa5a18 ("gpu: host1x: Set DMA ops on device
> creation") with the note:
> 
>      Currently host1x-instanciated devices have their dma_ops left to NULL,
>      which makes any DMA operation (like buffer import) on ARM64 fallback
>      to the dummy_dma_ops and fail with an error.
> 
> Since commit 14891af3799e ("iommu: Move the iommu driver sysfs setup into
> iommu_init/deinit_device()") this call now fails because the struct device
> is not fully configured enough to setup the sysfs and we now catch that
> error.
> 
> This failure means the DMA ops are no longer set during this failing call.
> 
> It seems this is no longer a problem because
> commit 07397df29e57 ("dma-mapping: move dma configuration to bus
> infrastructure") added another call to of_dma_configure() inside the
> bus_type->dma_configure() callback.
> 
> So long as a driver is probed the to the device it will have DMA properly
> setup in the ordinary way.
> 
> Remove the unnecessary call which also removes the new long print:
> 
> [    1.200004] host1x drm: iommu configuration for device failed with -ENOENT
> 
> Reported-by: Diogo Ivo <diogo.ivo@tecnico.ulisboa.pt>
> Closes: https://lore.kernel.org/all/bbmhcoghrprmbdibnjum6lefix2eoquxrde7wyqeulm4xabmlm@b6jy32saugqh/
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Closes: https://lore.kernel.org/all/b0334c5e-3a6c-4b58-b525-e72bed8899b3@nvidia.com/
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>   drivers/gpu/host1x/bus.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
> index 84d042796d2e66..61214d35cadc34 100644
> --- a/drivers/gpu/host1x/bus.c
> +++ b/drivers/gpu/host1x/bus.c
> @@ -458,8 +458,6 @@ static int host1x_device_add(struct host1x *host1x,
>   	device->dev.bus = &host1x_bus_type;
>   	device->dev.parent = host1x->dev;
>   
> -	of_dma_configure(&device->dev, host1x->dev->of_node, true);
> -
>   	device->dev.dma_parms = &device->dma_parms;
>   	dma_set_max_seg_size(&device->dev, UINT_MAX);


In my case the warning is coming from the of_dma_configure_id() in 
drivers/gpu/host1x/context.c. So with the above change I am still seeing 
the warning.

BTW, the subject prefix should be 'gpu: host1x:' for this change.

Jon

-- 
nvpublic