linux-kernel - Re: [PATCH v1] arm64: dts: imx8mm: fix missing pgc_vpu

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Date: Tue, 09 Apr 2024 17:44:37 +0100
From: Vitor Soares <ivitro@...il.com>
To: Lucas Stach <l.stach@...gutronix.de>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
 <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,  Sascha Hauer
 <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>
Cc: Vitor Soares <vitor.soares@...adex.com>, devicetree@...r.kernel.org, 
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v1] arm64: dts: imx8mm: fix missing pgc_vpu_* power
 domain parent

On Tue, 2024-04-09 at 16:36 +0200, Lucas Stach wrote:
> Am Dienstag, dem 09.04.2024 um 14:22 +0100 schrieb Vitor Soares:
> > Hi Lucas,
> > 
> > Thanks for your feedback.
> > 
> > On Tue, 2024-04-09 at 11:13 +0200, Lucas Stach wrote:
> > > Hi Vitor,
> > > 
> > > Am Dienstag, dem 09.04.2024 um 09:58 +0100 schrieb Vitor Soares:
> > > > From: Vitor Soares <vitor.soares@...adex.com>
> > > > 
> > > > The pgc_vpu_* nodes miss the reference to the power domain
> > > > parent,
> > > > leading the system to hang during the resume.
> > > > 
> > > This change is not correct. The vpumix domain is controlled
> > > through
> > > the
> > > imx8mm-vpu-blk-ctrl and must not be directly triggered by the
> > > child
> > > domains in order to guarantee proper power sequencing.
> > > 
> > > If the sequencing is incorrect for resume, it needs to be fixed
> > > in
> > > the
> > > blk-ctrl driver. I'll happily assist if you have any questions
> > > about
> > > this intricate mix between GPC and blk-ctrl hardware/drivers.
> >  
> > I'm new into the topic, so I tried to follow same approach as in
> > imx8mp
> > DT.
> > 
> That's a good hint, the 8MP VPU GPC node additions missed my radar.
> The
> direct dependency there between the GPC domains is equally wrong.
> 
> > I also checked the imx8mq DT and it only have one domain for the
> > VPU in the GPC. It seem blk-ctrl also dependes on pgc_vpu_* to work
> > properly.
> > 
> > The blk-ctrl driver hangs on imx8m_blk_ctrl_power_on() when access
> > the
> > ip registers for the soft reset. I tried to power-up the before the
> > soft reset, but it didn't work.
> > 
> The runtime_pm_get_sync() at the start of that function should ensure
> that bus GPC domain aka vpumix is powered up. Can you check if that
> is
> happening?

I checked bc->bus_power_dev->power.runtime_status and it is RPM_ACTIVE.

Am I looking to on the right thing? It is RPM_ACTIVE event before
runtime_pm_get_sync().


> 
> Regards,
> Lucas
> 
> > Do you have an idea how we can address this within blk-ctrl?
> > 
> > Best regards,
> > Vitor