[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam@freescale.com>

According to e9fd66defd (ARM: mx6: define CONFIG_ARM_ERRATA_742230), the 
CONFIG_ARM_ERRATA_742230 option should only be applied to multi-core
variants, so restrict its usage for quad and dual-lite only.

Quoting Shawn Guo [2]:

"The sololite has the same core version as dual/quad - r2p10.  The
help text of erratum 742230 in kernel suggests that only version
r1p0..r2p2 are affected.  So it sounds like the erratum 742230 should be
irrelevant to i.MX6 SoCs.  However we were running into a reboot issue
on multi-core i.MX6 SoCs.  There was a quite long discussion [1] about
it.  Though we did not reach a conclusion in the thread, one ARM people
sent me a private message, suggesting this should be an ARM core issue
and workaround for erratum 742230 might help.  And it turns out what he
said is true.  And that's why I came up with the commit e9fd66defd (ARM:
mx6: define CONFIG_ARM_ERRATA_742230) to turn on the erratum for imx6
dual/quad.

Shawn

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/thread.html#113096"

[2] http://lists.denx.de/pipermail/u-boot/2014-January/170424.html

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
Changes since v1:
- Improve commit log

 include/configs/mx6_common.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/configs/mx6_common.h b/include/configs/mx6_common.h
index 514d634..0b8db85 100644
--- a/include/configs/mx6_common.h
+++ b/include/configs/mx6_common.h
@@ -17,7 +17,9 @@
 #ifndef __MX6_COMMON_H
 #define __MX6_COMMON_H
 
+#if defined(CONFIG_MX6Q) ||  defined(CONFIG_MX6DL)
 #define CONFIG_ARM_ERRATA_742230
+#endif
 #define CONFIG_ARM_ERRATA_743622
 #define CONFIG_ARM_ERRATA_751472
 #define CONFIG_BOARD_POSTCLK_INIT
-- 
1.8.1.2

[U-Boot] [PATCH v2 2/2] mx6slevk: Include "mx6_common.h"

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam@freescale.com>

Include "mx6_common.h" so that some ARM errata are applied and also the
vddsoc regulator can be changed.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
Changes since v1:
- None

 include/configs/mx6slevk.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/configs/mx6slevk.h b/include/configs/mx6slevk.h
index 7abad08..b29f78c 100644
--- a/include/configs/mx6slevk.h
+++ b/include/configs/mx6slevk.h
@@ -11,6 +11,7 @@
 
 #include <asm/arch/imx-regs.h>
 #include <asm/sizes.h>
+#include "mx6_common.h"
 
 #define CONFIG_MX6
 #define CONFIG_DISPLAY_CPUINFO
-- 
1.8.1.2

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Dirk Behme]

Hi Fabio,

On 08.01.2014 14:59, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
>
> According to e9fd66defd (ARM: mx6: define CONFIG_ARM_ERRATA_742230), the
> CONFIG_ARM_ERRATA_742230 option should only be applied to multi-core
> variants, so restrict its usage for quad and dual-lite only.

Just for my understanding: Is there a technical reason not to use this 
errata on single core (solo/sololite)? I.e. do you see any real issues 
using this errata on solo/sololite?

Or is this patch "just out of formal" aspects? I.e. there are no 
positive/negative issues seen on solo/sololite, but the documentation 
tells that it shouldn't be used on solo/sololite, so disable it?

Best regards

Dirk

> Quoting Shawn Guo [2]:
>
> "The sololite has the same core version as dual/quad - r2p10.  The
> help text of erratum 742230 in kernel suggests that only version
> r1p0..r2p2 are affected.  So it sounds like the erratum 742230 should be
> irrelevant to i.MX6 SoCs.  However we were running into a reboot issue
> on multi-core i.MX6 SoCs.  There was a quite long discussion [1] about
> it.  Though we did not reach a conclusion in the thread, one ARM people
> sent me a private message, suggesting this should be an ARM core issue
> and workaround for erratum 742230 might help.  And it turns out what he
> said is true.  And that's why I came up with the commit e9fd66defd (ARM:
> mx6: define CONFIG_ARM_ERRATA_742230) to turn on the erratum for imx6
> dual/quad.
>
> Shawn
>
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/thread.html#113096"
>
> [2] http://lists.denx.de/pipermail/u-boot/2014-January/170424.html
>
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
> ---
> Changes since v1:
> - Improve commit log
>
>   include/configs/mx6_common.h | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/include/configs/mx6_common.h b/include/configs/mx6_common.h
> index 514d634..0b8db85 100644
> --- a/include/configs/mx6_common.h
> +++ b/include/configs/mx6_common.h
> @@ -17,7 +17,9 @@
>   #ifndef __MX6_COMMON_H
>   #define __MX6_COMMON_H
>
> +#if defined(CONFIG_MX6Q) ||  defined(CONFIG_MX6DL)
>   #define CONFIG_ARM_ERRATA_742230
> +#endif
>   #define CONFIG_ARM_ERRATA_743622
>   #define CONFIG_ARM_ERRATA_751472
>   #define CONFIG_BOARD_POSTCLK_INIT

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Fabio Estevam]

Hi Dirk,

On Wed, Jan 8, 2014 at 12:07 PM, Dirk Behme <dirk.behme@de.bosch.com> wrote:

> Just for my understanding: Is there a technical reason not to use this
> errata on single core (solo/sololite)? I.e. do you see any real issues using
> this errata on solo/sololite?

No real issue. It is unneeded for single core mx6 as explained by Shawn.

My real goal on this series was to enable the other ARM errata
available at mx6_common.h for sololite.

While reviewing the errata list, I learned that
CONFIG_ARM_ERRATA_742230 is not needed for solo/solo-lite, so that's
why I came up with this 1/2 patch.

Regards,

Fabio Estevam

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Hui.Liu at freescale.com]

> -----Original Message-----
> From: Fabio Estevam [mailto:festevam at gmail.com]
> Sent: Wednesday, January 08, 2014 10:00 PM
> To: sbabic at denx.de
> Cc: shawn.guo at linaro.org; Liu Hui-R64343; u-boot at lists.denx.de; Estevam
> Fabio-R49496
> Subject: [PATCH v2 1/2] configs: mx6_common: Restrict
> CONFIG_ARM_ERRATA_742230 for multi-core
> 
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> According to e9fd66defd (ARM: mx6: define CONFIG_ARM_ERRATA_742230), the
> CONFIG_ARM_ERRATA_742230 option should only be applied to multi-core
> variants, so restrict its usage for quad and dual-lite only.
> 
> Quoting Shawn Guo [2]:
> 
> "The sololite has the same core version as dual/quad - r2p10.  The help
> text of erratum 742230 in kernel suggests that only version
> r1p0..r2p2 are affected.  So it sounds like the erratum 742230 should be
> irrelevant to i.MX6 SoCs.  However we were running into a reboot issue on
> multi-core i.MX6 SoCs.  There was a quite long discussion [1] about it.
> Though we did not reach a conclusion in the thread, one ARM people sent
> me a private message, suggesting this should be an ARM core issue and
> workaround for erratum 742230 might help.  And it turns out what he said
> is true.  And that's why I came up with the commit e9fd66defd (ARM:
> mx6: define CONFIG_ARM_ERRATA_742230) to turn on the erratum for imx6
> dual/quad.
> 
> Shawn
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-
> August/thread.html#113096"
> 
> [2] http://lists.denx.de/pipermail/u-boot/2014-January/170424.html


The commit log really get me confused, why we need enable one ERRATA which should not be applied?
This will make customer confused at all. We need find the real root-cause for it other than hack it
Otherwise, you will get more and more problems sooner or later...

If you looking at the link in [1], it said, this issue only affected with v6+v7 one zImage kernel,
And not exist with v7 only kernel, which means something should be wrong with v6+v7 one zImage kernel.


Jason Liu

> 
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
> ---
> Changes since v1:
> - Improve commit log
> 
>  include/configs/mx6_common.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/configs/mx6_common.h b/include/configs/mx6_common.h
> index 514d634..0b8db85 100644
> --- a/include/configs/mx6_common.h
> +++ b/include/configs/mx6_common.h
> @@ -17,7 +17,9 @@
>  #ifndef __MX6_COMMON_H
>  #define __MX6_COMMON_H
> 
> +#if defined(CONFIG_MX6Q) ||  defined(CONFIG_MX6DL)
>  #define CONFIG_ARM_ERRATA_742230
> +#endif
>  #define CONFIG_ARM_ERRATA_743622
>  #define CONFIG_ARM_ERRATA_751472
>  #define CONFIG_BOARD_POSTCLK_INIT
> --
> 1.8.1.2
> 
> 

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Shawn Guo]

On Thu, Jan 09, 2014 at 03:50:06AM +0000, Hui.Liu at freescale.com wrote:
> The commit log really get me confused, why we need enable one ERRATA which should not be applied?

It's been enabled as a workaround for the reboot issue we were seeing
before.  But I get reminded that the workaround may not be needed
anymore, because of the recent kernel commit 87a84b69 (ARM: imx: replace
imx6q_restart() with mxc_restart()).  The real change is that we do not
call of_iomap() in restart hook now.

Fabio,

Can you give it a test to see if reboot works fine with v3.13-rc kernel
with dropping the ERRATA from u-boot?  If reboot works and nothing else
breaks, we may want to just remove the ERRATA selection from u-boot.

> This will make customer confused at all. We need find the real root-cause for it other than hack it
> Otherwise, you will get more and more problems sooner or later...

If you go through the thread [1], you will see that the root-cause had
pretty much been identified, - issuing dmb instructions in a tight loop
causes the problem.  But people did not reach a conclusion how it should
be fixed.

> 
> If you looking at the link in [1], it said, this issue only affected with v6+v7 one zImage kernel,
> And not exist with v7 only kernel, which means something should be wrong with v6+v7 one zImage kernel.

Again, if you go though the discussion, you will find the issue could be
easily made up on v7 only kernel.

Shawn

[1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/180876

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Fabio Estevam]

On Thu, Jan 9, 2014 at 4:28 AM, Shawn Guo <shawn.guo@linaro.org> wrote:

> Fabio,
>
> Can you give it a test to see if reboot works fine with v3.13-rc kernel
> with dropping the ERRATA from u-boot?  If reboot works and nothing else
> breaks, we may want to just remove the ERRATA selection from u-boot.

Tested on mx6sl and mx6q and I could run 'reboot' from Linux without
CONFIG_ARM_ERRATA_742230.

To be in the safe side I will send a v3 targeted for the upcoming
2014.01 release that only adds the 3 errata to mx6sl.

Regards,

Fabio Estevam

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Stefano Babic]

Hi Shawn,

On 09/01/2014 07:28, Shawn Guo wrote:
> On Thu, Jan 09, 2014 at 03:50:06AM +0000, Hui.Liu at freescale.com wrote:
>> The commit log really get me confused, why we need enable one ERRATA which should not be applied?
> 
> It's been enabled as a workaround for the reboot issue we were seeing
> before.  But I get reminded that the workaround may not be needed
> anymore, because of the recent kernel commit 87a84b69 (ARM: imx: replace
> imx6q_restart() with mxc_restart()).  The real change is that we do not
> call of_iomap() in restart hook now.
> 
> Fabio,
> 
> Can you give it a test to see if reboot works fine with v3.13-rc kernel
> with dropping the ERRATA from u-boot?  If reboot works and nothing else
> breaks, we may want to just remove the ERRATA selection from u-boot.
> 

+1

If the workaround must be set for dual/quad, it is not clear to me if
there are some disadvantages to let it enabled for solo.


>> This will make customer confused at all. We need find the real root-cause for it other than hack it
>> Otherwise, you will get more and more problems sooner or later...
> 
> If you go through the thread [1], you will see that the root-cause had
> pretty much been identified, - issuing dmb instructions in a tight loop
> causes the problem.  But people did not reach a conclusion how it should
> be fixed.

Exactly, and more frightening IMHO is what can happen is user space if
gcc uses dmb.

Regards,
Stefano

-- 
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================

[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Stefano Babic]

Hi Fabio,

On 09/01/2014 11:55, Fabio Estevam wrote:
> On Thu, Jan 9, 2014 at 4:28 AM, Shawn Guo <shawn.guo@linaro.org> wrote:
> 
>> Fabio,
>>
>> Can you give it a test to see if reboot works fine with v3.13-rc kernel
>> with dropping the ERRATA from u-boot?  If reboot works and nothing else
>> breaks, we may want to just remove the ERRATA selection from u-boot.
> 
> Tested on mx6sl and mx6q and I could run 'reboot' from Linux without
> CONFIG_ARM_ERRATA_742230.
> 
> To be in the safe side I will send a v3 targeted for the upcoming
> 2014.01 release that only adds the 3 errata to mx6sl.

Full agree.

Regards,
Stefano Babic



-- 
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================