Re: [PATCH/RFC 01/09] iommu/ipmmu-vmsa: Disable IPMMU when address expansion is not needed

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Magnus,

On Wed, Feb 20, 2019 at 3:55 PM Magnus Damm <magnus.damm@gmail.com> wrote:
> From: Magnus Damm <damm+renesas@opensource.se>
>
> Add a memory bank location check to the whitelist handling.
>
> Signed-off-by: Magnus Damm <damm+renesas@opensource.se>

Thanks for your patch!

> --- 0001/drivers/iommu/ipmmu-vmsa.c
> +++ work/drivers/iommu/ipmmu-vmsa.c     2019-02-20 22:59:28.589893396 +0900

> @@ -797,6 +798,12 @@ static bool ipmmu_slave_whitelist(struct
>         if (!soc_device_match(soc_rcar_gen3_whitelist))
>                 return false;
>
> +       /* In case all system memory fits within 32 bits of physical space
> +        * then assume the IPMMU will not be needed for address expansion.
> +        */
> +       if (memblock_end_of_DRAM() <= SZ_4G)

Can this give a compiler warning on arm32 when CONFIG_ARM_LPAE=n?

> +               return false;
> +
>         /* Check whether this slave device can work with the IPMMU */
>         for (i = 0; i < ARRAY_SIZE(rcar_gen3_slave_whitelist); i++) {
>                 if (!strcmp(dev_name(dev), rcar_gen3_slave_whitelist[i]))

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds