On 27/07/2024 00:59, Roman Kisel wrote:
> @@ -2338,6 +2372,21 @@ static int vmbus_device_add(struct platform_device *pdev)
> cur_res = &res->sibling;
> }
>
> + /*
> + * Hyper-V always assumes DMA cache coherency, and the DMA subsystem
> + * might default to 'not coherent' on some architectures.
> + * Avoid high-cost cache coherency maintenance done by the CPU.
> + */
> +#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
> + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
> + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
> +
> + if (!of_property_read_bool(np, "dma-coherent"))
> + pr_warn("Assuming cache coherent DMA transactions, no 'dma-coherent' node supplied\n");
Why do you need this property at all, if it is allways dma-coherent? Are
you supporting dma-noncoherent somewhere?
Best regards,
Krzysztof
