linux-kernel - Re: [PATCH] ARM: imx6ull: Make suspend/resume work like on 6ul

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Message-ID: <1496828647.28352.58.camel@nxp.com>
Date:   Wed, 7 Jun 2017 12:44:07 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Anson Huang <anson.huang@....com>, Shawn Guo <shawnguo@...nel.org>
CC:     Peter Chen <peter.chen@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Lucas Stach <l.stach@...gutronix.de>
Subject: Re: [PATCH] ARM: imx6ull: Make suspend/resume work like on 6ul

On Wed, 2017-06-07 at 03:38 +0000, Anson Huang wrote:
> > -----Original Message-----
> > From: Shawn Guo [mailto:shawnguo@...nel.org]
> > Sent: 2017-06-07 11:21 AM
> > To: Anson Huang <anson.huang@....com>
> > Cc: Leonard Crestez <leonard.crestez@....com>; Peter Chen
> > <peter.chen@....com>; linux-kernel@...r.kernel.org; Fabio Estevam
> > <fabio.estevam@....com>; linux-arm-kernel@...ts.infradead.org; Lucas Stach
> > <l.stach@...gutronix.de>
> > Subject: Re: [PATCH] ARM: imx6ull: Make suspend/resume work like on 6ul
> > 
> > On Tue, Jun 06, 2017 at 01:51:53PM +0300, Leonard Crestez wrote:
> > > 
> > > On Mon, 2017-06-05 at 13:37 +0800, Shawn Guo wrote:
> > > > 
> > > > On Tue, May 30, 2017 at 07:11:19PM +0300, Leonard Crestez wrote:
> > > > > 
> > > > > 
> > > > > Suspend and resume on imx6ull is currenty not working because of
> > > > > some missed checks where behavior should match imx6ul.
> > > > > 
> > > > > Signed-off-by: Leonard Crestez <leonard.crestez@....com>
> > > > > ---
> > > > >  arch/arm/mach-imx/mxc.h     | 6 ++++++
> > > > >  arch/arm/mach-imx/pm-imx6.c | 6 ++++--
> > > > >  2 files changed, 10 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/arch/arm/mach-imx/mxc.h b/arch/arm/mach-imx/mxc.h
> > > > > index 34f2ff6..e00d626 100644
> > > > > --- a/arch/arm/mach-imx/mxc.h
> > > > > +++ b/arch/arm/mach-imx/mxc.h
> > > > > @@ -39,6 +39,7 @@
> > > > >  #define MXC_CPU_IMX6SX		0x62
> > > > >  #define MXC_CPU_IMX6Q		0x63
> > > > >  #define MXC_CPU_IMX6UL		0x64
> > > > > +#define MXC_CPU_IMX6ULL		0x65
> > > > Since you are adding a new CPU type, you should probably patch
> > > > imx_soc_device_init() for it as well.
> > > Ok, I will resend as a 2-patch series.
> > > 
> > > BTW, it actually seems to me that setting
> > BM_CLPCR_BYP_MMDC_CH0_LPM_HS
> > > 
> > > on imx6sl/sx/ul/ull is not actually needed. That bit (19) is
> > > documented as "reserved" in the Reference Manual and likely ignored by
> > hardware.
> > > 
> > > 
> > > As far as I understand the MMDC on imx6qdl has two channels and unless
> > > 2-channel mode is enabled (not currently supported) the handshake with
> > > CH1 needs to be disabled. Other reduced chips only have one MMDC
> > > channel and that is CH1 (CH0 was removed) and nothing needs to be done
> > > from them. The only important thing is to avoid setting
> > > BM_CLPCR_BYP_MMDC_CH1_LPM_HS.
> > > 
> > > However perhaps what I am saying is wrong for some early chip versions?
> > > Because this behavior of setting BM_CLPCR_BYP_MMDC_CH0_LPM_HS has
> > been
> > > 
> > > in the kernel for a long time.
> As far as I know, since i.MX6SX, we only use MMDC_CH1, but MMDC_CH0 is still
> there and we need to bypass its handshake when entering low power mode.
> 
> The bit 19 in DOC is incorrect, I remembered I ever tried it and discuss with design
> time, they request DOC team to update DOC,
> but I think doc team forgot to do it. You can try removing this bit 19 setting
> and see if standby/mem suspend can still work? And try to modify this bit 19 value
> to see if it can be modified.

After some testing it seems that setting MMDC_CH0 is indeed required.
So nevermind

I remember testing this earlier and getting the opposite result but I
probably confused the STOP_POWER_ON and STOP_POWER_OFF paths.

--
Regards,
Leonard