linux-kernel - Re: [PATCH v3 4/4] firmware: ti_sci: restore clock context during resume in BOARDCFG

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Message-ID: <e8c4d832-3146-4fad-a0f6-0e2df77e83c0@bootlin.com>
Date: Thu, 18 Dec 2025 11:19:39 +0100
From: Thomas Richard <thomas.richard@...tlin.com>
To: Dhruva Gole <d-gole@...com>
Cc: Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
 Santosh Shilimkar <ssantosh@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Gregory CLEMENT <gregory.clement@...tlin.com>,
 richard.genoud@...tlin.com, Udit Kumar <u-kumar1@...com>,
 Prasanth Mantena <p-mantena@...com>, Abhash Kumar <a-kumar2@...com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-clk@...r.kernel.org
Subject: Re: [PATCH v3 4/4] firmware: ti_sci: restore clock context during
 resume in BOARDCFG_MANAGED mode

On 12/17/25 7:07 AM, Dhruva Gole wrote:
> On Dec 05, 2025 at 15:28:26 +0100, Thomas Richard (TI.com) wrote:
>> In BOARDCFG_MANAGED mode, the firmware cannot restore the clock rates and
>> the clock parents. This responsibility is therefore delegated to the ti_sci
>> driver, which uses clk_restore_context() to trigger the context_restore()
>> operation for all registered clocks, including those managed by the sci-clk
>> driver. The sci-clk driver implements the context_restore() operation to
>> ensure rates and clock parents are correctly restored.
>>
>> Signed-off-by: Thomas Richard (TI.com) <thomas.richard@...tlin.com>
>> ---
>>  drivers/firmware/ti_sci.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
>> index 8d94745376e2a..6ef687e481c49 100644
>> --- a/drivers/firmware/ti_sci.c
>> +++ b/drivers/firmware/ti_sci.c
>> @@ -9,6 +9,7 @@
>>  #define pr_fmt(fmt) "%s: " fmt, __func__
>>  
>>  #include <linux/bitmap.h>
>> +#include <linux/clk.h>
>>  #include <linux/cpu.h>
>>  #include <linux/debugfs.h>
>>  #include <linux/export.h>
>> @@ -3980,6 +3981,8 @@ static int ti_sci_resume_noirq(struct device *dev)
>>  				if (ret)
>>  					return ret;
>>  			}
>> +
>> +			clk_restore_context();
> 
> Here as well, make it conditional to only BOARDCFG_MANAGED. Other
> platforms/ firmwares have lived without this for a while now, and it's
> evident that we don't always need this.

It is already conditionally done to only BOARDCFG_MANAGED.

> 
> Thinking more about this, I think we're over using this BOARDCFG_MANAGED
> mode a bit much. We should really just come up with new FW caps for
> this, one for clk_restore , other for the previous IRQ restore patch.
> 
> That's the only way I can see this scaling. In future if we ever need
> more devices that may actually be BOARDCFG_MANAGED, but don't need the
> IRQ or clock restoration then the current approach won't work.
> 
> MODE should only be passed in the prepare_sleep, where it makes sense.
> Using it for anything else just does not feel clean to me.

Fair point. Restoring clocks and IRQs is more related to the fact that
DM-Firmware on Jacinto platforms does not have suspend-resume support
than the BOARDCFG_MANAGED mode. I guess we could imagine in the future
having suspend-resume support in Jacinto DM-Firmware, so no need to
restore clocks and IRQs anymore, but the mode remains BOARDCFG_MANAGED.

Best Regards,
Thomas