linux-kernel - Re: [PATCH v4 06/18] pmdomain: thead: Add power-domain driver for TH1520

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Message-ID: <CAPDyKFrcs5Hc-X6qExEA992MoQcakCuKRjw7cek3KpYZihsLFw@mail.gmail.com>
Date: Fri, 14 Feb 2025 12:15:58 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Michal Wilczynski <m.wilczynski@...sung.com>
Cc: mturquette@...libre.com, sboyd@...nel.org, robh@...nel.org, 
	krzk+dt@...nel.org, conor+dt@...nel.org, drew@...7.com, guoren@...nel.org, 
	wefu@...hat.com, jassisinghbrar@...il.com, paul.walmsley@...ive.com, 
	palmer@...belt.com, aou@...s.berkeley.edu, frank.binns@...tec.com, 
	matt.coster@...tec.com, maarten.lankhorst@...ux.intel.com, mripard@...nel.org, 
	tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, jszhang@...nel.org, 
	p.zabel@...gutronix.de, m.szyprowski@...sung.com, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, dri-devel@...ts.freedesktop.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v4 06/18] pmdomain: thead: Add power-domain driver for TH1520

On Tue, 28 Jan 2025 at 20:48, Michal Wilczynski
<m.wilczynski@...sung.com> wrote:
>
> The T-Head TH1520 SoC contains multiple power islands that can be
> programmatically turned on and off using the AON (Always-On) protocol
> and a hardware mailbox [1]. The relevant mailbox driver has already been
> merged into the mainline kernel in commit 5d4d263e1c6b ("mailbox:
> Introduce support for T-head TH1520 Mailbox driver");
>
> Introduce a power-domain driver for the TH1520 SoC, which is using AON
> firmware protocol to communicate with E902 core through the hardware
> mailbox. This way it can send power on/off commands to the E902 core.
>
> The interaction with AUDIO power island e.g trying to turn it OFF proved
> to crash the firmware running on the E902 core. Introduce the workaround
> to disable interacting with the power island.
>
> Link: https://openbeagle.org/beaglev-ahead/beaglev-ahead/-/blob/main/docs/TH1520%20System%20User%20Manual.pdf [1]
>
> Signed-off-by: Michal Wilczynski <m.wilczynski@...sung.com>
> ---

[...]

> +
> +static int th1520_pd_probe(struct platform_device *pdev)
> +{
> +       struct generic_pm_domain **domains;
> +       struct genpd_onecell_data *pd_data;
> +       struct th1520_aon_chan *aon_chan;
> +       struct device *dev = &pdev->dev;
> +       int i;
> +
> +       aon_chan = dev_get_drvdata(dev->parent);
> +       if (!aon_chan) {
> +               dev_err(dev, "Failed to get AON channel from parent\n");
> +               return -EINVAL;
> +       }

As pointed out on patch4. Rather than receiving the aon_chang from the
parent device like this, it seems better to receive it from a call to
a library function provided by the FW library.

> +
> +       domains = devm_kcalloc(dev, ARRAY_SIZE(th1520_pd_ranges),
> +                              sizeof(*domains), GFP_KERNEL);
> +       if (!domains)
> +               return -ENOMEM;
> +
> +       pd_data = devm_kzalloc(dev, sizeof(*pd_data), GFP_KERNEL);
> +       if (!pd_data)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < ARRAY_SIZE(th1520_pd_ranges); i++) {
> +               struct th1520_power_domain *pd;
> +
> +               if (th1520_pd_ranges[i].disabled)
> +                       continue;
> +
> +               pd = th1520_add_pm_domain(dev, &th1520_pd_ranges[i]);
> +               if (IS_ERR(pd))
> +                       return PTR_ERR(pd);
> +
> +               pd->aon_chan = aon_chan;
> +               domains[i] = &pd->genpd;
> +               dev_dbg(dev, "added power domain %s\n", pd->genpd.name);
> +       }
> +
> +       pd_data->domains = domains;
> +       pd_data->num_domains = ARRAY_SIZE(th1520_pd_ranges);
> +       pd_data->xlate = th1520_pd_xlate;
> +
> +       /*
> +        * Initialize all power domains to off to ensure they start in a
> +        * low-power state. This allows device drivers to manage power
> +        * domains by turning them on or off as needed.
> +        */
> +       th1520_pd_init_all_off(domains, dev);
> +
> +       return of_genpd_add_provider_onecell(dev->parent->of_node, pd_data);
> +}
> +
> +static struct platform_driver th1520_pd_driver = {
> +       .driver = {
> +               .name = "th1520-pd",
> +       },
> +       .probe = th1520_pd_probe,
> +};
> +module_platform_driver(th1520_pd_driver);

There is no ->remove() callback.

Either add one or make this a builtin_platform_driver() with
"suppress_bind_attrs = true".

> +
> +MODULE_AUTHOR("Michal Wilczynski <m.wilczynski@...sung.com>");
> +MODULE_DESCRIPTION("T-HEAD TH1520 SoC power domain controller");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>

Besides the minor thing above, this looks good to me!

Kind regards
Uffe