linux-kernel - Re: [PATCH] firmware: ti_sci: set IO Isolation only if the firmware is capable

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Message-ID: <20251031041013.kfyveddq7rkmtvfv@wince>
Date: Thu, 30 Oct 2025 23:10:13 -0500
From: Nishanth Menon <nm@...com>
To: "Thomas Richard (TI.com)" <thomas.richard@...tlin.com>
CC: Tero Kristo <kristo@...nel.org>, Santosh Shilimkar <ssantosh@...nel.org>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Gregory CLEMENT
	<gregory.clement@...tlin.com>, Richard Genoud <richard.genoud@...tlin.com>,
	Udit Kumar <u-kumar1@...com>, Prasanth Mantena <p-mantena@...com>, "Abhash
 Kumar" <a-kumar2@...com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] firmware: ti_sci: set IO Isolation only if the firmware
 is capable

On 10:31-20251014, Thomas Richard (TI.com) wrote:
> Add the IO_ISOLATION firmware capability, and set IO Isolation during
> suspend only if the firmware is capable.

How about:
Prevent calling ti_sci_cmd_set_io_isolation() on
firmware that does not support the IO_ISOLATION capability. Add
the MSG_FLAG_CAPS_IO_ISOLATION capability flag and check it before
attempting to set IO isolation during suspend/resume operations.

Without this check, systems with older firmware may experience
undefined behavior or errors when entering/exiting suspend states.

> 
> Fixes: ec24643bdd62 ("firmware: ti_sci: Add system suspend and resume call")
> Signed-off-by: Thomas Richard (TI.com) <thomas.richard@...tlin.com>
> ---
>  drivers/firmware/ti_sci.c | 21 +++++++++++++--------
>  drivers/firmware/ti_sci.h |  2 ++
>  2 files changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
> index 49fd2ae01055d0f425062147422471f0fd49e4bd..8d96a3c12b36a908097805b44dc3343172fbbfec 100644
> --- a/drivers/firmware/ti_sci.c
> +++ b/drivers/firmware/ti_sci.c
> @@ -3751,9 +3751,11 @@ static int __maybe_unused ti_sci_suspend_noirq(struct device *dev)
>  	struct ti_sci_info *info = dev_get_drvdata(dev);
>  	int ret = 0;
>  
> -	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_ENABLE);
> -	if (ret)
> -		return ret;
> +	if (info->fw_caps & MSG_FLAG_CAPS_IO_ISOLATION) {
> +		ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_ENABLE);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	return 0;
>  }
> @@ -3767,9 +3769,11 @@ static int __maybe_unused ti_sci_resume_noirq(struct device *dev)
>  	u8 pin;
>  	u8 mode;
>  
> -	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_DISABLE);
> -	if (ret)
> -		return ret;
> +	if (info->fw_caps & MSG_FLAG_CAPS_IO_ISOLATION) {
> +		ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_DISABLE);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	ret = ti_sci_msg_cmd_lpm_wake_reason(&info->handle, &source, &time, &pin, &mode);
>  	/* Do not fail to resume on error as the wake reason is not critical */
> @@ -3928,11 +3932,12 @@ static int ti_sci_probe(struct platform_device *pdev)
>  	}
>  
>  	ti_sci_msg_cmd_query_fw_caps(&info->handle, &info->fw_caps);
> -	dev_dbg(dev, "Detected firmware capabilities: %s%s%s%s\n",
> +	dev_dbg(dev, "Detected firmware capabilities: %s%s%s%s%s\n",
>  		info->fw_caps & MSG_FLAG_CAPS_GENERIC ? "Generic" : "",
>  		info->fw_caps & MSG_FLAG_CAPS_LPM_PARTIAL_IO ? " Partial-IO" : "",
>  		info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED ? " DM-Managed" : "",
> -		info->fw_caps & MSG_FLAG_CAPS_LPM_ABORT ? " LPM-Abort" : ""
> +		info->fw_caps & MSG_FLAG_CAPS_LPM_ABORT ? " LPM-Abort" : "",
> +		info->fw_caps & MSG_FLAG_CAPS_IO_ISOLATION ? " IO-Isolation" : ""
>  	);
>  
>  	ti_sci_setup_ops(info);
> diff --git a/drivers/firmware/ti_sci.h b/drivers/firmware/ti_sci.h
> index 701c416b2e78f8ef20ce6741a88ffa6fd4853b2d..7559cde17b6ccfeeb1bc357fce5c5767c3f75c54 100644
> --- a/drivers/firmware/ti_sci.h
> +++ b/drivers/firmware/ti_sci.h
> @@ -149,6 +149,7 @@ struct ti_sci_msg_req_reboot {
>   *		MSG_FLAG_CAPS_LPM_PARTIAL_IO: Partial IO in LPM
>   *		MSG_FLAG_CAPS_LPM_DM_MANAGED: LPM can be managed by DM
>   *		MSG_FLAG_CAPS_LPM_ABORT: Abort entry to LPM
> + *		MSG_FLAG_CAPS_IO_ISOLATION: IO Isolation support
>   *
>   * Response to a generic message with message type TI_SCI_MSG_QUERY_FW_CAPS
>   * providing currently available SOC/firmware capabilities. SoC that don't
> @@ -160,6 +161,7 @@ struct ti_sci_msg_resp_query_fw_caps {
>  #define MSG_FLAG_CAPS_LPM_PARTIAL_IO	TI_SCI_MSG_FLAG(4)
>  #define MSG_FLAG_CAPS_LPM_DM_MANAGED	TI_SCI_MSG_FLAG(5)
>  #define MSG_FLAG_CAPS_LPM_ABORT		TI_SCI_MSG_FLAG(9)
> +#define MSG_FLAG_CAPS_IO_ISOLATION	TI_SCI_MSG_FLAG(7)
>  #define MSG_MASK_CAPS_LPM		GENMASK_ULL(4, 1)
>  	u64 fw_caps;
>  } __packed;
> 
> ---
> base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> change-id: 20251013-ti-sci-io-isolation-63a8bcd9d4e9
> 
> Best regards,
> -- 
> Thomas Richard (TI.com) <thomas.richard@...tlin.com>
> 

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