[U-Boot-Users] [PATCH] USB: shutdown USB before booting

[U-Boot-Users] [PATCH] USB: shutdown USB before booting

[Markus Klotzbücher]

This patch fixes a potentially serious issue related to USB which was
discouvered by Martin Krause <martin.krause@tqs.de> and fixed for
ARM920T. Martin wrote:

  Turn off USB to prevent the host controller from writing to the
  SDRAM while Linux is booting. This could happen, because the HCCA
  (Host Controller Communication Area) lies within the SDRAM and the
  host controller writes continously to this area (as busmaster!), for
  example to increase the HccaFrameNumber variable, which happens
  every 1 ms.

This is a slightly modified version of the patch in order to shutdown
USB when booting on all architectures.

Signed-off-by: Markus Klotzbuecher <mk@denx.de>
---
 common/cmd_bootm.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
index 959689e..f914815 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -36,6 +36,10 @@
 #include <lmb.h>
 #include <asm/byteorder.h>
 
+#if (CONFIG_COMMANDS & CFG_CMD_USB)
+#include <usb.h>
+#endif
+
 #ifdef CFG_HUSH_PARSER
 #include <hush.h>
 #endif
@@ -213,6 +217,20 @@ int do_bootm (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 	 */
 	iflag = disable_interrupts();
 
+#if (CONFIG_COMMANDS & CFG_CMD_USB)
+       /*
+        * turn off USB to prevent the host controller from writing to the
+        * SDRAM while Linux is booting. This could happen (at least for OHCI
+        * controller), because the HCCA (Host Controller Communication Area)
+        * lies within the SDRAM and the host controller writes continously to
+        * this area (as busmaster!). The HccaFrameNumber is for example
+        * updated every 1 ms within the HCCA structure in SDRAM! For more
+        * details see the OpenHCI specification.
+        */
+	usb_stop();
+#endif
+
+
 #ifdef CONFIG_AMIGAONEG3SE
 	/*
 	 * We've possible left the caches enabled during
-- 
1.5.5.1


Best regards

Markus Klotzbuecher

--
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de

[U-Boot-Users] [PATCH] USB: shutdown USB before booting

[Stefan Roese]

Hi Markus,

On Thursday 10 July 2008, Markus Klotzb?cher wrote:
> This patch fixes a potentially serious issue related to USB which was
> discouvered by Martin Krause <martin.krause@tqs.de> and fixed for
> ARM920T. Martin wrote:
>
>   Turn off USB to prevent the host controller from writing to the
>   SDRAM while Linux is booting. This could happen, because the HCCA
>   (Host Controller Communication Area) lies within the SDRAM and the
>   host controller writes continously to this area (as busmaster!), for
>   example to increase the HccaFrameNumber variable, which happens
>   every 1 ms.
>
> This is a slightly modified version of the patch in order to shutdown
> USB when booting on all architectures.

Yes, I remember hearing of this problem. I thought it was already fixed. Seems 
not to be the case. Please find a comment below.

> Signed-off-by: Markus Klotzbuecher <mk@denx.de>
> ---
>  common/cmd_bootm.c |   18 ++++++++++++++++++
>  1 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c

By implementing this usb_stop() in do_bootm() you prevent this problem in many 
cases (e.g. Linux booting). But unfortunately not in all cases. For 
example "bootelf" or "bootvx" are not fixed.

Can't this be solved in a different way. By calling usb_stop each time after 
an USB command completes. IIRC, this is how it is done in the U-Boot network 
implementation too.

What do you think?

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80  Email: office at denx.de
=====================================================================

[U-Boot-Users] [PATCH] USB: shutdown USB before booting

[Wolfgang Denk]

In message <200807101502.14543.sr@denx.de> you wrote:
> 
> Yes, I remember hearing of this problem. I thought it was already fixed. Seems 
> not to be the case. Please find a comment below.

I thought so, too. But Martin Krause's patch somehow got stuck in the
gearbox.

> By implementing this usb_stop() in do_bootm() you prevent this problem in many 
> cases (e.g. Linux booting). But unfortunately not in all cases. For 
> example "bootelf" or "bootvx" are not fixed.

You are right.

> Can't this be solved in a different way. By calling usb_stop each time after 
> an USB command completes. IIRC, this is how it is done in the U-Boot network 
> implementation too.
> 
> What do you think?

I pulled in the current patch so we reduce  the  problem  as  far  as
possible; any better implementation is welcome.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
In the beginning there was nothing.
And the Lord said "Let There Be Light!"
And still there was nothing, but at least now you could see it.

[U-Boot-Users] [PATCH] USB: shutdown USB before booting

[Wolfgang Denk]

In message <87iqvdzz1u.fsf@denx.de> you wrote:
> 
> This patch fixes a potentially serious issue related to USB which was
> discouvered by Martin Krause <martin.krause@tqs.de> and fixed for
> ARM920T. Martin wrote:
> 
>   Turn off USB to prevent the host controller from writing to the
>   SDRAM while Linux is booting. This could happen, because the HCCA
>   (Host Controller Communication Area) lies within the SDRAM and the
>   host controller writes continously to this area (as busmaster!), for
>   example to increase the HccaFrameNumber variable, which happens
>   every 1 ms.
> 
> This is a slightly modified version of the patch in order to shutdown
> USB when booting on all architectures.
> 
> Signed-off-by: Markus Klotzbuecher <mk@denx.de>
> ---
>  common/cmd_bootm.c |   18 ++++++++++++++++++
>  1 files changed, 18 insertions(+), 0 deletions(-)

Thanks, Markus. This is so urgent that I pull this directly.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
How does a project get to be a year late?      ... One day at a time.