linux-kernel - Re: [PATCH v5 2/3] remoteproc: imx_rproc: skip clock enable when M-core is managed by the SCU

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Message-ID: <20250624161500.odnopjv5jqvyyus2@hiagonb>
Date: Tue, 24 Jun 2025 13:15:00 -0300
From: Hiago De Franco <hiagofranco@...il.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, linux-pm@...r.kernel.org,
	linux-remoteproc@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Bjorn Andersson <andersson@...nel.org>,
	Hiago De Franco <hiago.franco@...adex.com>, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Peng Fan <peng.fan@....nxp.com>, daniel.baluta@....com,
	iuliana.prodan@....nxp.com,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Peng Fan <peng.fan@....com>
Subject: Re: [PATCH v5 2/3] remoteproc: imx_rproc: skip clock enable when
 M-core is managed by the SCU

Hi Mathieu,

On Mon, Jun 23, 2025 at 09:15:52AM -0600, Mathieu Poirier wrote:
> Hi Hiago,
> 
> On Tue, Jun 17, 2025 at 04:34:49PM -0300, Hiago De Franco wrote:
> > From: Hiago De Franco <hiago.franco@...adex.com>
> > 
> > For the i.MX8X and i.MX8 family SoCs, when the M-core is powered up
> > by the bootloader, M-core and Linux are in same SCFW (System Controller
> > Firmware) partition, so linux has permission to control M-core.
> 
> Ok
> 
> > 
> > But when M-core is started, the SCFW will automatically enable the clock
> 
> I find the "But when M-core is started" part confusing.  Started by who?  And
> are you making a distinction between "powered up" and "started"?  It is not
> possible for someone that doesn't have HW documentation to understand what is
> going on.

Ok, understood, I will improve this in the next revision. Just to make
clear, I am talking about Cortex-A bootloader starting Cortex-M (U-Boot
bootaux command in this case). This means powered up, started and
running.

> 
> > and configure the rate, and any users that want to enable the clock will
> > get error 'LOCKED' from SCFW. So current imx_rproc.c probe function
> > fails because clk_prepare_enable also fails. With that, the M-core power
> > domain is powered off when it is still running, causing a SCU (System
> > Controller Unit) fault reset, and the system restarts.
> > 
> > To address the issue, ignore handling the clk for i.MX8X and i.MX8 M-core,
> > because SCFW will automatically enable and configure the clock.
> > 
> > Suggested-by: Peng Fan <peng.fan@....com>
> > Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
> > Signed-off-by: Hiago De Franco <hiago.franco@...adex.com>
> > ---
> > v4 -> v5:
> >  - Unchanged.
> > v3 -> v4:
> >  - Unchanged.
> > v2 -> v3:
> >  - Unchanged.
> > v1 -> v2:
> >  - Commit description updated, as suggested. Fixed Peng Fan email.
> > ---
> >  drivers/remoteproc/imx_rproc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> > index 74299af1d7f1..627e57a88db2 100644
> > --- a/drivers/remoteproc/imx_rproc.c
> > +++ b/drivers/remoteproc/imx_rproc.c
> > @@ -1029,8 +1029,8 @@ static int imx_rproc_clk_enable(struct imx_rproc *priv)
> >  	struct device *dev = priv->dev;
> >  	int ret;
> >  
> > -	/* Remote core is not under control of Linux */
> > -	if (dcfg->method == IMX_RPROC_NONE)
> > +	/* Remote core is not under control of Linux or it is managed by SCU API */
> > +	if (dcfg->method == IMX_RPROC_NONE || dcfg->method == IMX_RPROC_SCU_API)
> >  		return 0;
> >  
> >  	priv->clk = devm_clk_get(dev, NULL);
> > -- 
> > 2.39.5
> >