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Date: Wed, 13 Jan 2021 12:27:13 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
LKML <linux-kernel@...r.kernel.org>,
"Rafael J . Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] soc: samsung: pm_domains: Convert to regular platform driver
On Wed, Jan 13, 2021 at 3:03 AM Marek Szyprowski
<m.szyprowski@...sung.com> wrote:
>
> When Exynos power domain driver was introduced, the only way to ensure
> that power domains will be instantiated before the devices which belongs
> to them was to initialize them early enough, before the devices are
> instantiated in the system. This in turn required not to use any platform
> device infrastructure at all, as there have been no way to ensure proper
> probe order between devices.
>
> This has been finally changed and patch e590474768f1 ("driver core: Set
> fw_devlink=on by default") ensures that each device will be probbed only
> when its resource providers are ready. This allows to convert Exynos
> power domain driver to regular platform driver.
>
> This is also required by the mentioned commit to enable probing any
> device which belongs to the Exynos power domains, as otherwise the core
> won't notice that the power domains are in fact available.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
> Some more comments are in the following thread:
> https://lore.kernel.org/lkml/2556a69b-5da5-bf80-e051-df2d02fbc40f@samsung.com/
> ---
> drivers/soc/samsung/pm_domains.c | 97 ++++++++++++++++----------------
> 1 file changed, 48 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/soc/samsung/pm_domains.c b/drivers/soc/samsung/pm_domains.c
> index ab8582971bfc..5ec0c13f0aaf 100644
> --- a/drivers/soc/samsung/pm_domains.c
> +++ b/drivers/soc/samsung/pm_domains.c
> @@ -16,7 +16,7 @@
> #include <linux/delay.h>
> #include <linux/of_address.h>
> #include <linux/of_platform.h>
> -#include <linux/sched.h>
> +#include <linux/pm_runtime.h>
>
> struct exynos_pm_domain_config {
> /* Value for LOCAL_PWR_CFG and STATUS fields for each domain */
> @@ -73,15 +73,15 @@ static int exynos_pd_power_off(struct generic_pm_domain *domain)
> return exynos_pd_power(domain, false);
> }
>
> -static const struct exynos_pm_domain_config exynos4210_cfg __initconst = {
> +static const struct exynos_pm_domain_config exynos4210_cfg = {
> .local_pwr_cfg = 0x7,
> };
>
> -static const struct exynos_pm_domain_config exynos5433_cfg __initconst = {
> +static const struct exynos_pm_domain_config exynos5433_cfg = {
> .local_pwr_cfg = 0xf,
> };
>
> -static const struct of_device_id exynos_pm_domain_of_match[] __initconst = {
> +static const struct of_device_id exynos_pm_domain_of_match[] = {
> {
> .compatible = "samsung,exynos4210-pd",
> .data = &exynos4210_cfg,
> @@ -92,7 +92,7 @@ static const struct of_device_id exynos_pm_domain_of_match[] __initconst = {
> { },
> };
>
> -static __init const char *exynos_get_domain_name(struct device_node *node)
> +static const char *exynos_get_domain_name(struct device_node *node)
> {
> const char *name;
>
> @@ -101,60 +101,44 @@ static __init const char *exynos_get_domain_name(struct device_node *node)
> return kstrdup_const(name, GFP_KERNEL);
> }
>
> -static __init int exynos4_pm_init_power_domain(void)
> +static int exynos_pd_probe(struct platform_device *pdev)
> {
> - struct device_node *np;
> - const struct of_device_id *match;
> -
> - for_each_matching_node_and_match(np, exynos_pm_domain_of_match, &match) {
> - const struct exynos_pm_domain_config *pm_domain_cfg;
> - struct exynos_pm_domain *pd;
> - int on;
> + const struct exynos_pm_domain_config *pm_domain_cfg;
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct of_phandle_args child, parent;
> + struct exynos_pm_domain *pd;
> + int on, ret;
>
> - pm_domain_cfg = match->data;
> + pm_domain_cfg = of_device_get_match_data(dev);
> + pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
> + if (!pd)
> + return -ENOMEM;
>
> - pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> - if (!pd) {
> - of_node_put(np);
> - return -ENOMEM;
> - }
> - pd->pd.name = exynos_get_domain_name(np);
> - if (!pd->pd.name) {
> - kfree(pd);
> - of_node_put(np);
> - return -ENOMEM;
> - }
> + pd->pd.name = exynos_get_domain_name(np);
> + if (!pd->pd.name)
> + return -ENOMEM;
>
> - pd->base = of_iomap(np, 0);
> - if (!pd->base) {
> - pr_warn("%s: failed to map memory\n", __func__);
> - kfree_const(pd->pd.name);
> - kfree(pd);
> - continue;
> - }
> -
> - pd->pd.power_off = exynos_pd_power_off;
> - pd->pd.power_on = exynos_pd_power_on;
> - pd->local_pwr_cfg = pm_domain_cfg->local_pwr_cfg;
> + pd->base = of_iomap(np, 0);
> + if (!pd->base) {
> + kfree_const(pd->pd.name);
> + return -ENODEV;
> + }
>
> - on = readl_relaxed(pd->base + 0x4) & pd->local_pwr_cfg;
> + pd->pd.power_off = exynos_pd_power_off;
> + pd->pd.power_on = exynos_pd_power_on;
> + pd->local_pwr_cfg = pm_domain_cfg->local_pwr_cfg;
>
> - pm_genpd_init(&pd->pd, NULL, !on);
> - of_genpd_add_provider_simple(np, &pd->pd);
> - }
> + on = readl_relaxed(pd->base + 0x4) & pd->local_pwr_cfg;
>
> - /* Assign the child power domains to their parents */
> - for_each_matching_node(np, exynos_pm_domain_of_match) {
> - struct of_phandle_args child, parent;
> + pm_genpd_init(&pd->pd, NULL, !on);
> + ret = of_genpd_add_provider_simple(np, &pd->pd);
>
> + if (ret == 0 && of_parse_phandle_with_args(np, "power-domains",
> + "#power-domain-cells", 0, &parent) == 0) {
> child.np = np;
> child.args_count = 0;
>
> - if (of_parse_phandle_with_args(np, "power-domains",
> - "#power-domain-cells", 0,
> - &parent) != 0)
> - continue;
> -
> if (of_genpd_add_subdomain(&parent, &child))
> pr_warn("%pOF failed to add subdomain: %pOF\n",
> parent.np, child.np);
> @@ -163,6 +147,21 @@ static __init int exynos4_pm_init_power_domain(void)
> parent.np, child.np);
> }
>
> - return 0;
> + pm_runtime_enable(dev);
> + return ret;
> +}
> +
> +static struct platform_driver exynos_pd_driver = {
> + .probe = exynos_pd_probe,
> + .driver = {
> + .name = "exynos-pd",
> + .of_match_table = exynos_pm_domain_of_match,
> + .suppress_bind_attrs = true,
> + }
> +};
> +
> +static __init int exynos4_pm_init_power_domain(void)
> +{
> + return platform_driver_register(&exynos_pd_driver);
> }
> core_initcall(exynos4_pm_init_power_domain);
> --
> 2.17.1
>
Skimmed through this patch and at a high level, it looks good for what
it's trying to do. Thanks for doing this!
Btw, I assume that this won't work with fw_devlink=off/permissive
(default since 5.10 or earlier)? My concern is that we might
temporarily set fw_devlink=permissive by default if the other
breakages aren't fixed in time for 5.12? How do you want to handle that?
-Saravana
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