Re: [PATCH v4 08/11] iommu/mediatek: Add a gap for the iova regions

[AngeloGioacchino Del Regno]

Il 15/02/23 07:25, Yong Wu ha scritto:
> As the removed property in the vcodec dt-binding, the property is:
> dma-ranges = <0x1 0x0 0x0 0x40000000 0x0 0xfff00000>;
>
> The length is 0xfff0_0000 rather than 0x1_0000_0000, this means it
> requires 1M as a gap. This is because the end address for some vcodec
> HW is (address + size). If the size is 4G, the end address may be
> 0x2_0000_0000, and the width for vcodec register only is 32, then the
> HW may get the ZERO address.
>
> Currently the consumer's dma-ranges property doesn't work, IOMMU
> has to consider this case. Add a bigger gap(8M) for all the regions
> to avoid it.
>
> Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
> Hi AngeloGioacchino,
> I define a new macro for this, I think it is a small change, thus keep
> you R-b.
> Thanks.

Hello!
You added a nice comment to the new definition describing that there's a 8M gap,
so it's completely fine; you can keep my R-b on this one just fine!

Regards,
Angelo