linux-kernel - Re: [PATCH v3 2/6] firmware: ti

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Message-ID: <20241025174204.xwmsn2arcy4q63xu@reaction>
Date: Fri, 25 Oct 2024 12:42:04 -0500
From: Nishanth Menon <nm@...com>
To: Markus Schneider-Pargmann <msp@...libre.com>
CC: Tero Kristo <kristo@...nel.org>, Santosh Shilimkar <ssantosh@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, Anand Gadiyar <gadiyar@...com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Vishal Mahaveer
	<vishalm@...com>,
        Kevin Hilman <khilman@...libre.com>, Dhruva Gole
	<d-gole@...com>
Subject: Re: [PATCH v3 2/6] firmware: ti_sci: Partial-IO support

On 16:39-20241012, Markus Schneider-Pargmann wrote:
[...]
> 
> The possible wakeup devices are found by checking which devices are
> powered by the regulator supplying the "vddshv_canuart" line. These are
> considered possible wakeup sources. Only wakeup sources that are
> actually enabled by the user will be considered as a an active wakeup
> source. If none of the wakeup sources are enabled the system will do a
> normal poweroff. If at least one wakeup source is enabled it will
> instead send a TI_SCI_MSG_PREPARE_SLEEP message from the sys_off
> handler. Sending this message will result in an immediate shutdown of
> the system. No execution is expected after this point. The code will
> wait for 5s and do an emergency_restart afterwards if Partial-IO wasn't
> entered at that point.
> 
[...]

> +static bool tisci_canuart_wakeup_enabled(struct ti_sci_info *info)
> +{
> +	static const char canuart_name[] = "vddshv_canuart";
> +	struct device_node *wakeup_node = NULL;
> +
> +	for (wakeup_node = of_find_node_with_property(NULL, "vio-supply");
> +	     wakeup_node;
> +	     wakeup_node = of_find_node_with_property(wakeup_node, "vio-supply")) {
> +		struct device_node *supply_node;
> +		const char *supply_name;
> +		struct platform_device *pdev;
> +		int ret;
> +
> +		supply_node = of_parse_phandle(wakeup_node, "vio-supply", 0);
> +		if (!supply_node)
> +			continue;
> +
> +		ret = of_property_read_string(supply_node, "regulator-name", &supply_name);
> +		of_node_put(supply_node);
> +		if (ret) {
> +			dev_warn(info->dev, "Failed to parse vio-supply phandle at %pOF %d\n",
> +				 wakeup_node, ret);
> +			continue;
> +		}
> +
> +		if (strncmp(canuart_name, supply_name, strlen(canuart_name)))
> +			continue;
> +
> +		pdev = of_find_device_by_node(wakeup_node);
> +		if (!pdev)
> +			continue;
> +
> +		if (device_may_wakeup(&pdev->dev)) {
> +			dev_dbg(info->dev, "%pOF identified as wakeup source for Partial-IO\n",
> +				wakeup_node);
> +			put_device(&pdev->dev);
> +			of_node_put(wakeup_node);
> +			return true;
> +		}
> +		put_device(&pdev->dev);
> +	}
> +
> +	return false;
> +}
> +

What is the binding that supports this? I just do not think that
scanning the entire tree for vio-supply implies you will get thr right
property here.

Just giving an example to illustrate this point:
Documentation/devicetree/bindings/net/wireless/ti,wl1251.txt says it
needs vio-supply -> so i have a node with the wireless supply as
vio-supply -> Since we are scanning from NULL for vio-supply, we hit
that, that is a bad choice for enabling io-retention.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D