USB: shutdown USB before booting
PATCH 1/1 USB: shutdown USB before booting
This patch fixes a potentially serious issue related to USB which was discouvered by Martin Krause <[email protected]> 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.
--- common/cmd_bootm.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-)
common/cmd_bootm.c +18 -0
@@ -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
Signature · 11 lines
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
PATCH 1/1 USB: shutdown USB before booting
Hi Markus,
Quoted 11 lines · Markus Klotzb?cher
This patch fixes a potentially serious issue related to USB which was discouvered by Martin Krause <[email protected]> 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.
Quoted 2 lines
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.
common/cmd_bootm.c
Quoted 6 lines
Signed-off-by Markus Klotzbuecher <[email protected]>--- common/cmd_bootm.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-)common/cmd_bootm.c +0
-0
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
=====================================================================
PATCH 1/1 USB: shutdown USB before booting
Quoted 3 lines · In message <[email protected]> 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.
Quoted 3 lines
By implementing this
usb_stop()indo_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.
Quoted 5 lines
Can't this be solved in a different way. By calling
usb_stopeach 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
Signature · 6 lines
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.
PATCH 1/1 USB: shutdown USB before booting
In reply to Markus KlotzbücherQuoted 12 lines · In message <[email protected]> you wrote:
This patch fixes a potentially serious issue related to USB which was discouvered by Martin Krause <[email protected]> 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.
Quoted 7 lines
This is a slightly modified version of the patch in order to shutdown USB when booting on all architectures.
Signed-off-by Markus Klotzbuecher <[email protected]>--- 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
Signature · 4 lines
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.