linux-kernel - Re: [PATCH 1/3] remoteproc: imx_rproc: skip clock enable when M-core is managed by the SCU

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Message-ID: <20250506123619.egobussm6b74imso@hiago-nb>
Date: Tue, 6 May 2025 09:36:19 -0300
From: Hiago De Franco <hiagofranco@...il.com>
To: Peng Fan <peng.fan@....nxp.com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>,
	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,
	daniel.baluta@....com, iuliana.prodan@....nxp.com,
	Fabio Estevam <festevam@...il.com>,
	Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH 1/3] remoteproc: imx_rproc: skip clock enable when M-core
 is managed by the SCU

Hi Peng,

On Tue, May 06, 2025 at 12:38:35PM +0800, Peng Fan wrote:
> On Mon, May 05, 2025 at 12:48:47PM -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
> >before Linux starts (e.g., by the bootloader) and it is being managed by
> >the SCU, the SCFW will not allow the kernel to enable the clock again.
> >This currently causes an SCU fault reset when the M-core is up and
> >running and the kernel boots, resetting the system.
> >
> >Therefore, add a check in the clock enable function to not execute it if
> >the M-core is being managed by the SCU.
> >
> >This change affects only the i.MX8X and i.MX8 family SoCs, as this is
> >under the IMX_RPROC_SCU_API method.
> 
> I would rewrite as below: "
> 
> 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.
> 
> But when M-core is started, the SCFW will automatically enable the clock
> and configure the rate, and any users that wanna to enable the clock
> will get error 'LOCKED' from SCFW. So current imx_rproc.c probe function
> gets failure because clk_prepare_enable returns failure. Then
> the power domain of M-core is powered off when M-core is still running,
> SCU(System Controller Unit) will get a fault reset, and system restarts.
> 
> To address the issue, ignore handling the clk for i.MX8X and i.MX8 M-core,
> because SCFW automatically enables and configures the clock.
> "
> 
> You may update if you wanna.
> 
> >
> >Signed-off-by: Hiago De Franco <hiago.franco@...adex.com>
> >Suggested-by: Peng Fan <peng.fan@....nxp.com>
> 
> -> peng.fan@....com

Thanks for the review, I will update the suggestions on a v2. Meanwhile,
I will wait a little bit for other feedbacks.

> 
> Thanks,
> Peng
> 
> >---
> > 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
> >

Cheers,
Hiago.