Hi Vineet, On Thu, 2017-08-31 at 09:31 -0700, Vineet Gupta wrote: > On 08/31/2017 07:22 AM, Alexey Brodkin wrote: > > > > This is useful to make sure no stale data exists in caches after bootloaders. > > The worst thing could be some lines of cache were locked in a bootloader > > for example during DDR recalibration and never unlocked. This may lead > > to really unpredictable issues later down the line. > > > > Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com> > > --- > > ? arch/arc/kernel/head.S | 16 ++++++++++++++++ > > ? 1 file changed, 16 insertions(+) > > > > diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S > > index 8b90d25a15cc..04e28b664183 100644 > > --- a/arch/arc/kernel/head.S > > +++ b/arch/arc/kernel/head.S > > @@ -34,6 +34,10 @@ > > ? #endif > > ?? sr r5, [ARC_REG_IC_CTRL] > > ?? > > + ; Invalidate entire I$ > > + mov r5, 1 > > + sr r5, [ARC_REG_IC_IVIC] > > + > > ? 1: > > ?? lr r5, [ARC_REG_DC_BCR] > > ?? breq????r5, 0, 1f ; D$ doesn't exist > > @@ -46,6 +50,18 @@ > > ? #endif > > ?? sr r5, [ARC_REG_DC_CTRL] > > ?? > > + ; Flush entire D$ > > + mov r5, 1 > > + sr r5, [ARC_REG_DC_FLSH] > > + ; Wait for flush operation to complete > > +1: > > + lr r5, [ARC_REG_DC_CTRL] > > + bbit1 r5, DC_CTRL_FLUSH_STATUS, 1b > > + > > + ; Invalidate entire D$ > > + mov r5, 1 > > + sr r5, [ARC_REG_DC_IVDC] > > + > > AFAIK uboot already flushes the caches before handing control over to kernel - so? > why do we need it here. > If uboot is locking lines, it needs to fix that and not penalize the general case? > with or w/o uboot ! U-Boot indeed flushes caches.. but doesn't invalidate them! And only invalidation unlocks locked lines. That indeed should be added in U-Boot but I'd say above stuff doesn't influence a lot code size or execution time while makes system more fool-proof. -Alexey
