From: Max Krummenacher <max.oss.09@gmail.com>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Max Krummenacher <max.krummenacher@toradex.com>,
Lucas Stach <l.stach@pengutronix.de>,
linux-arm-kernel@lists.infradead.org,
Fabio Estevam <festevam@gmail.com>,
Rouven Czerwinski <r.czerwinski@pengutronix.de>,
linux-kernel@vger.kernel.org,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Sascha Hauer <s.hauer@pengutronix.de>,
Russell King <linux@armlinux.org.uk>,
Shawn Guo <shawnguo@kernel.org>,
NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [PATCH 1/1] ARM: imx: build suspend-imx6.S with arm instruction set
Date: Mon, 11 Jan 2021 19:30:51 +0100 [thread overview]
Message-ID: <147692b37063057ce4128894db112caf9320b65b.camel@gmail.com> (raw)
In-Reply-To: <ecc65820-6b94-bb11-f475-aa0296fce5b8@pengutronix.de>
Resent due to gmail adding HTML, sorry for the noise.
Am Montag, den 11.01.2021, 18:49 +0100 schrieb
Ahmad Fatoum:
>
> On 11.01.21 16:17, Max Krummenacher wrote:
> > When the kernel is configured to use the Thumb-2 instruction set
> > "suspend-to-memory" fails to resume. Observed on a Colibri iMX6ULL
> > (i.MX 6ULL) and Apalis iMX6 (i.MX 6Q).
> >
> > It looks like the CPU resumes unconditionally in ARM instruction mode
> > and then chokes on the presented Thumb-2 code it should execute.
> >
> > Fix this by using the arm instruction set for all code in
> > suspend-imx6.S.
> >
> > Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
> >
> > ---
> >
> > arch/arm/mach-imx/suspend-imx6.S | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-imx/suspend-imx6.S b/arch/arm/mach-imx/suspend-imx6.S
> > index 1eabf2d2834be..e06f946b75b96 100644
> > --- a/arch/arm/mach-imx/suspend-imx6.S
> > +++ b/arch/arm/mach-imx/suspend-imx6.S
> > @@ -67,6 +67,7 @@
> > #define MX6Q_CCM_CCR 0x0
> >
> > .align 3
> > + .arm
>
> You had a return to thumb at the end of this subroutine in the cover letter,
> yet here it's omitted. Why?
Now the whole subroutine is compiled for ARM and the return address has bit
0 set so that on jumping back to the caller the CPU will switch back to
Thumb-2.
Probably the return to Thumb-2 isn't needed in the cover letter solution
and it would also work to finish the subroutine in ARM instruction set.
However it looks strange to me if a function which begins with the ARM
instruction set would come to the return in Thumb-2.
>
> >
> > .macro sync_l2_cache
> >
> >
WARNING: multiple messages have this Message-ID (diff)
From: Max Krummenacher <max.oss.09@gmail.com>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Rouven Czerwinski <r.czerwinski@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
NXP Linux Team <linux-imx@nxp.com>,
Max Krummenacher <max.krummenacher@toradex.com>,
Fabio Estevam <festevam@gmail.com>,
linux-arm-kernel@lists.infradead.org,
Lucas Stach <l.stach@pengutronix.de>
Subject: Re: [PATCH 1/1] ARM: imx: build suspend-imx6.S with arm instruction set
Date: Mon, 11 Jan 2021 19:30:51 +0100 [thread overview]
Message-ID: <147692b37063057ce4128894db112caf9320b65b.camel@gmail.com> (raw)
In-Reply-To: <ecc65820-6b94-bb11-f475-aa0296fce5b8@pengutronix.de>
Resent due to gmail adding HTML, sorry for the noise.
Am Montag, den 11.01.2021, 18:49 +0100 schrieb
Ahmad Fatoum:
>
> On 11.01.21 16:17, Max Krummenacher wrote:
> > When the kernel is configured to use the Thumb-2 instruction set
> > "suspend-to-memory" fails to resume. Observed on a Colibri iMX6ULL
> > (i.MX 6ULL) and Apalis iMX6 (i.MX 6Q).
> >
> > It looks like the CPU resumes unconditionally in ARM instruction mode
> > and then chokes on the presented Thumb-2 code it should execute.
> >
> > Fix this by using the arm instruction set for all code in
> > suspend-imx6.S.
> >
> > Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
> >
> > ---
> >
> > arch/arm/mach-imx/suspend-imx6.S | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm/mach-imx/suspend-imx6.S b/arch/arm/mach-imx/suspend-imx6.S
> > index 1eabf2d2834be..e06f946b75b96 100644
> > --- a/arch/arm/mach-imx/suspend-imx6.S
> > +++ b/arch/arm/mach-imx/suspend-imx6.S
> > @@ -67,6 +67,7 @@
> > #define MX6Q_CCM_CCR 0x0
> >
> > .align 3
> > + .arm
>
> You had a return to thumb at the end of this subroutine in the cover letter,
> yet here it's omitted. Why?
Now the whole subroutine is compiled for ARM and the return address has bit
0 set so that on jumping back to the caller the CPU will switch back to
Thumb-2.
Probably the return to Thumb-2 isn't needed in the cover letter solution
and it would also work to finish the subroutine in ARM instruction set.
However it looks strange to me if a function which begins with the ARM
instruction set would come to the return in Thumb-2.
>
> >
> > .macro sync_l2_cache
> >
> >
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-01-11 18:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 15:17 [PATCH 0/1] ARM: imx: build suspend-imx6.S with arm instruction set Max Krummenacher
2021-01-11 15:17 ` Max Krummenacher
2021-01-11 15:17 ` [PATCH 1/1] " Max Krummenacher
2021-01-11 15:17 ` Max Krummenacher
2021-01-11 17:38 ` Oleksandr Suvorov
2021-01-11 17:38 ` Oleksandr Suvorov
2021-01-11 17:49 ` Ahmad Fatoum
2021-01-11 17:49 ` Ahmad Fatoum
2021-01-11 18:30 ` Max Krummenacher [this message]
2021-01-11 18:30 ` Max Krummenacher
2021-01-18 6:45 ` Shawn Guo
2021-01-18 6:45 ` Shawn Guo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=147692b37063057ce4128894db112caf9320b65b.camel@gmail.com \
--to=max.oss.09@gmail.com \
--cc=a.fatoum@pengutronix.de \
--cc=festevam@gmail.com \
--cc=kernel@pengutronix.de \
--cc=l.stach@pengutronix.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-imx@nxp.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=max.krummenacher@toradex.com \
--cc=r.czerwinski@pengutronix.de \
--cc=s.hauer@pengutronix.de \
--cc=shawnguo@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.