Hi Lucas,
On Fri, 2018-09-14 at 11:24 +0200, Lucas Stach wrote:
> The etnaviv device is a virtual device backing the DRM device, which may
> drive multiple hardware GPU core devies. As most of the dma-mapping handling
> is done through the virtual device, we need to make sure that a proper DMA
> setup is in place. The easiest way to get a reasonable configuration is
> to let the virtual device share the DMA configuration with one of the GPU
> devices, so call of_dma_configure() with the right parameters manually.
>
> This assumes that all etnaviv driven GPU devices in the system share the
> same DMA configuration. If we ever encounter a SoC where the GPUs are on
> busses with different offsets or behind different IOMMUs that will require
> much deeper changes to the driver, as we would need to implement etnaviv
> specific versions of most of the DRM helper functions.
>
> For now we should be fine with this solution.
This works fine on HSDK, thanks!
Tested-By: Eugeniy Paltsev <Eugeniy.Paltsev at synopsys.com>
>
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> ---
> drivers/gpu/drm/etnaviv/etnaviv_drv.c | 27 +++++++++++++++++++++------
> 1 file changed, 21 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> index 9b2720b41571..83c1f46670bf 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> @@ -592,8 +592,6 @@ static int etnaviv_pdev_probe(struct platform_device *pdev)
> struct device *dev = &pdev->dev;
> struct component_match *match = NULL;
>
> - dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
> -
> if (!dev->platform_data) {
> struct device_node *core_node;
>
> @@ -655,13 +653,30 @@ static int __init etnaviv_init(void)
> for_each_compatible_node(np, NULL, "vivante,gc") {
> if (!of_device_is_available(np))
> continue;
> - pdev = platform_device_register_simple("etnaviv", -1,
> - NULL, 0);
> - if (IS_ERR(pdev)) {
> - ret = PTR_ERR(pdev);
> +
> + pdev = platform_device_alloc("etnaviv", -1);
> + if (!pdev) {
> + ret = -ENOMEM;
> + of_node_put(np);
> + goto unregister_platform_driver;
> + }
> + pdev->dev.coherent_dma_mask = DMA_BIT_MASK(40);
> + pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
> +
> + /*
> + * Apply the same DMA configuration to the virtual etnaviv
> + * device as the GPU we found. This assumes that all Vivante
> + * GPUs in the system share the same DMA constraints.
> + */
> + of_dma_configure(&pdev->dev, np, true);
> +
> + ret = platform_device_add(pdev);
> + if (ret) {
> + platform_device_put(pdev);
> of_node_put(np);
> goto unregister_platform_driver;
> }
> +
> etnaviv_drm = pdev;
> of_node_put(np);
> break;
--
Eugeniy Paltsev
