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Message-ID: <CAC=S1njT6ygGuZDPU5KDW94Nu-TbM21DM-6HdR7Pio=WTD_eQA@mail.gmail.com>
Date: Fri, 27 Jun 2025 20:12:39 +0800
From: Fei Shao <fshao@...omium.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: linux-mediatek@...ts.infradead.org, robh@...nel.org, krzk+dt@...nel.org,
conor+dt@...nel.org, matthias.bgg@...il.com, ulf.hansson@...aro.org,
y.oudjana@...tonmail.com, wenst@...omium.org, lihongbo22@...wei.com,
mandyjh.liu@...iatek.com, mbrugger@...e.com, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-pm@...r.kernel.org, kernel@...labora.com
Subject: Re: [PATCH v1 02/13] pmdomain: mediatek: Refactor bus protection
regmaps retrieval
On Mon, Jun 23, 2025 at 8:02 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> In preparation to add support for new generation SoCs like MT8196,
> MT6991 and other variants, which require to set bus protection on
> different busses than the ones found on legacy chips, and to also
> simplify and reduce memory footprint of this driver, refactor the
> mechanism to retrieve and use the bus protection regmaps.
>
> This is done by removing the three pointers to struct regmap from
> struct scpsys_domain (allocated for each power domain) and moving
> them to the main struct scpsys (allocated per driver instance) as
> an array of pointers to regmap named **bus_prot.
>
> That deprecates the old devicetree properties to grab phandles to
> the three predefined busses (infracfg, infracfg-nao and smi) and
> replaces it with a new property "mediatek,bus-protection" that is
> meant to be an array of phandles holding the same busses where
> required (for now - for legacy SoCs).
>
> The new bus protection phandles are indexed by the bus_prot_index
> member of struct scpsys, used to map "bus type" (ex.: infra, smi,
> etc) to the specific *bus_prot[x] element.
>
> While the old per-power-domain regmap pointers were removed, the
> support for old devicetree was retained by still checking if the
> new property (in DT) and new-style declaration (in SoC specific
> platform data) are both present at probe time.
>
> If those are not present, a lookup for the old properties will be
> done in all of the children of the power controller, and pointers
> to regmaps will be retrieved with the old properties, but then
> will be internally remapped to follow the new style regmap anyway
> as to let this driver benefit of the memory footprint reduction.
>
> Finally, it was necessary to change macros in mtk-pm-domains.h and
> in mt8365-pm-domains.h to make use of the new style bus protection
> declaration, as the actual HW block is now recognized not by flags
> but by its own scpsys_bus_prot_block enumeration.
>
> The BUS_PROT_(STA)_COMPONENT_{INFRA,INFRA_NAO,SMI} flags were also
> removed since they are now unused, and because that enumeration was
> initially meant to vary the logic of bus protection and not the bus
> where work is performed, anyway!
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
<snip>
>
> +static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *scpsys)
> +{
> + const u8 bp_blocks[3] = {
> + BUS_PROT_BLOCK_INFRA, BUS_PROT_BLOCK_SMI, BUS_PROT_BLOCK_INFRA_NAO
> + };
> + struct device_node *np = dev->of_node;
> + struct device_node *node, *smi_np;
> + int num_regmaps = 0, i, j;
> + struct regmap *regmap[3];
> +
> + /*
> + * Legacy code retrieves a maximum of three bus protection handles:
> + * some may be optional, or may not be, so the array of bp blocks
> + * that is normally passed in as platform data must be dynamically
> + * built in this case.
> + *
> + * Here, try to retrieve all of the regmaps that the legacy code
> + * supported and then count the number of the ones that are present,
> + * this makes it then possible to allocate the array of bus_prot
> + * regmaps and convert all to the new style handling.
> + */
> + node = of_find_node_with_property(np, "mediatek,infracfg");
> + if (node) {
> + regmap[0] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg");
> + of_node_put(node);
> + num_regmaps++;
> + if (IS_ERR(regmap[0]))
> + return dev_err_probe(dev, PTR_ERR(regmap[0]),
> + "%pOF: failed to get infracfg regmap\n",
> + node);
> + } else {
> + regmap[0] = NULL;
> + }
> +
> + node = of_find_node_with_property(np, "mediatek,smi");
> + if (node) {
> + smi_np = of_parse_phandle(node, "mediatek,smi", 0);
> + of_node_put(node);
> + if (!smi_np)
> + return -ENODEV;
> +
> + regmap[1] = device_node_to_regmap(smi_np);
> + num_regmaps++;
> + of_node_put(smi_np);
> + if (IS_ERR(regmap[1]))
> + return dev_err_probe(dev, PTR_ERR(regmap[1]),
> + "%pOF: failed to get SMI regmap\n",
> + node);
> + } else {
> + regmap[1] = NULL;
> + }
> +
> + node = of_find_node_with_property(np, "mediatek,infracfg-nao");
> + if (node) {
> + regmap[2] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg-nao");
> + num_regmaps++;
> + of_node_put(node);
> + if (IS_ERR(regmap[2]))
> + return dev_err_probe(dev, PTR_ERR(regmap[2]),
> + "%pOF: failed to get infracfg regmap\n",
> + node);
> + } else {
> + regmap[2] = NULL;
> + }
> +
> + scpsys->bus_prot = devm_kmalloc_array(dev, num_regmaps,
> + sizeof(*scpsys->bus_prot), GFP_KERNEL);
> + if (!scpsys->bus_prot)
> + return -ENOMEM;
> +
> + for (i = 0, j = 0; i < num_regmaps; i++) {
Did you mean BUS_PROT_BLOCK_COUNT?
Consider a case where only regmap[2] is configured.
Regards,
Fei
> + enum scpsys_bus_prot_block bp_type;
> +
> + if (!regmap[i])
> + continue;
> +
> + bp_type = bp_blocks[i];
> + scpsys->bus_prot_index[bp_type] = j;
> + scpsys->bus_prot[j] = regmap[i];
> +
> + j++;
> + }
> +
> + return 0;
> +}
> +
<snip>
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