| Message ID | 1312823424-9654-3-git-send-email-will.deacon@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 08/08/2011 12:10 PM, Will Deacon wrote: > The various reset routines in mach-realview rely on an FPGA to > power-cycle the board after writing some magic runes to memory-mapped > registers. > > This patch adds a dsb() following the writes, so that they become > visible before we mdelay(1000) in the arch_reset code. Without this > patch, the timeout would expire sporadically, causing the reset to fail. > > Signed-off-by: Will Deacon <will.deacon@arm.com> > --- > arch/arm/mach-realview/include/mach/system.h | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h > index a30f2e3..6657ff2 100644 > --- a/arch/arm/mach-realview/include/mach/system.h > +++ b/arch/arm/mach-realview/include/mach/system.h > @@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd) > */ > if (realview_reset) > realview_reset(mode); > + dsb(); Wouldn't it be better to do this globally. Rob
Hi Rob, On Mon, Aug 08, 2011 at 10:16:17PM +0100, Rob Herring wrote: > On 08/08/2011 12:10 PM, Will Deacon wrote: > > The various reset routines in mach-realview rely on an FPGA to > > power-cycle the board after writing some magic runes to memory-mapped > > registers. > > > > This patch adds a dsb() following the writes, so that they become > > visible before we mdelay(1000) in the arch_reset code. Without this > > patch, the timeout would expire sporadically, causing the reset to fail. > > > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > arch/arm/mach-realview/include/mach/system.h | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h > > index a30f2e3..6657ff2 100644 > > --- a/arch/arm/mach-realview/include/mach/system.h > > +++ b/arch/arm/mach-realview/include/mach/system.h > > @@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd) > > */ > > if (realview_reset) > > realview_reset(mode); > > + dsb(); > > Wouldn't it be better to do this globally. I'd rather leave it in the arch-specific code since otherwise it feels like we're leaking the actual reset implementation into the caller. Plus it's not entirely clear that there's a one-size-fits-all solution here. Cheers, Will
diff --git a/arch/arm/mach-realview/include/mach/system.h b/arch/arm/mach-realview/include/mach/system.h index a30f2e3..6657ff2 100644 --- a/arch/arm/mach-realview/include/mach/system.h +++ b/arch/arm/mach-realview/include/mach/system.h @@ -44,6 +44,7 @@ static inline void arch_reset(char mode, const char *cmd) */ if (realview_reset) realview_reset(mode); + dsb(); } #endif
The various reset routines in mach-realview rely on an FPGA to power-cycle the board after writing some magic runes to memory-mapped registers. This patch adds a dsb() following the writes, so that they become visible before we mdelay(1000) in the arch_reset code. Without this patch, the timeout would expire sporadically, causing the reset to fail. Signed-off-by: Will Deacon <will.deacon@arm.com> --- arch/arm/mach-realview/include/mach/system.h | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)