Re: [PATCH] accel/ivpu: Limit DMA address width to 42 bits on 40XX and later

[Dawid Osuchowski <dawid.osuchowski@linux.intel.com>]

On 2026-10-06 11:37 AM, Karol Wachowski wrote:
> On 40XX and later the NPU does not treat address bits 42 and above as
> part of the memory address, as the hardware uses them internally, but
> ivpu sets a 48-bit DMA mask for these generations.
> 
> In practice the IOMMU capabilities already limit the DMA addresses to
> 42 bits, so this does not fix an observed problem. Set the DMA mask to
> 42 bits anyway, so the driver does not depend on the IOMMU
> configuration to stay within the range the NPU can address. 37XX keeps
> its 38-bit mask.
> 

Reviewed-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>

> Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
> ---
>   drivers/accel/ivpu/ivpu_drv.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/accel/ivpu/ivpu_drv.c b/drivers/accel/ivpu/ivpu_drv.c
> index ab1a9448c2cc..6b71edf566e7 100644
> --- a/drivers/accel/ivpu/ivpu_drv.c
> +++ b/drivers/accel/ivpu/ivpu_drv.c
> @@ -709,7 +709,7 @@ static int ivpu_pci_init(struct ivpu_device *vdev)
>   	}
>   
>   	if (ivpu_hw_ip_gen(vdev) >= IVPU_HW_IP_40XX)
> -		dma_bits = 48;
> +		dma_bits = 42;
>   	else
>   		dma_bits = 38;
>