Re: [PATCH v2 2/7] iommu: mtk_iommu: Lookup phandle to retrieve syscon to infracfg

Yong Wu
2022-05-26T08:22:28Z

On Wed, 2022-05-18 at 12:04 +0200, AngeloGioacchino Del Regno wrote:
> This driver will get support for more SoCs and the list of infracfg
> compatibles is expected to grow: in order to prevent getting this
> situation out of control and see a long list of compatible strings,
> add support to retrieve a handle to infracfg's regmap through a
> new "mediatek,infracfg" phandle.
>
> In order to keep retrocompatibility with older devicetrees, the old
> way is kept in place, but also a dev_warn() was added to advertise
> this change in hope that the user will see it and eventually update
> the devicetree if this is possible.
>
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
> drivers/iommu/mtk_iommu.c | 40 +++++++++++++++++++++++++----------
> ----
> 1 file changed, 26 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 71b2ace74cd6..d16b95e71ded 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -1134,22 +1134,34 @@ static int mtk_iommu_probe(struct
> platform_device *pdev)
> data->protect_base = ALIGN(virt_to_phys(protect),
> MTK_PROTECT_PA_ALIGN);
>
> if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_4GB_MODE)) {
> - switch (data->plat_data->m4u_plat) {
> - case M4U_MT2712:
> - p = "mediatek,mt2712-infracfg";
> - break;
> - case M4U_MT8173:
> - p = "mediatek,mt8173-infracfg";
> - break;
> - default:
> - p = NULL;
> + infracfg = syscon_regmap_lookup_by_phandle(dev-
> >of_node, "mediatek,infracfg");
> + if (IS_ERR(infracfg)) {
> + dev_info(dev, "Cannot find phandle to
> mediatek,infracfg:"
> + " Please update your
> devicetree.\n");

Remove the log from Robin?

> + /*
> + * Legacy devicetrees will not specify a
> phandle to
> + * mediatek,infracfg: in that case, we use the
> older
> + * way to retrieve a syscon to infra.
> + *
> + * This is for retrocompatibility purposes
> only, hence
> + * no more compatibles shall be added to this.
> + */
> + switch (data->plat_data->m4u_plat) {
> + case M4U_MT2712:
> + p = "mediatek,mt2712-infracfg";
> + break;
> + case M4U_MT8173:
> + p = "mediatek,mt8173-infracfg";
> + break;
> + default:
> + p = NULL;
> + }

We already use "mediatek,infracfg" property for commonizing. For the
previous SoC, I also prefer to put the string into the platform data.

After this, "->m4u_plat" could be removed. Of course, this is not the
main purpose of this patchset. it also is ok currently.

> +
> + infracfg =
> syscon_regmap_lookup_by_compatible(p);
> + if (IS_ERR(infracfg))
> + return PTR_ERR(infracfg);
> }
>
> - infracfg = syscon_regmap_lookup_by_compatible(p);
> -
> - if (IS_ERR(infracfg))
> - return PTR_ERR(infracfg);
> -
> ret = regmap_read(infracfg, REG_INFRA_MISC, &val);
> if (ret)
> return ret;