Hi Wolfgang, Now that we keep the old speed on aligned access, I'm ok with the change and only see one typo in the comment.
> The MPC5200 has a nasty problem that will cause silent data corruption > when performing unaligned 16 or 32 byte accesses when reading from the > local bus - typically this affects reading from flash. The problem can > be easily shown: > > => md fc0c0000 10 > fc0c0000: 323e4337 01626f6f 74636d64 3d72756e 2>C7.bootcmd=run > fc0c0010: 206e6574 5f6e6673 00626f6f 7464656c net_nfs.bootdel > fc0c0020: 61793d35 00626175 64726174 653d3131 ay=5.baudrate=11 > fc0c0030: 35323030 00707265 626f6f74 3d656368 5200.preboot=ech > => md fc0c0001 10 > fc0c0001: 65636801 00000074 0000003d 00000020 ech....t...=... > fc0c0011: 0000005f 00000000 00000074 00000061 ..._.......t...a > fc0c0021: 00000000 00000064 00000065 00000035 .......d...e...5 > fc0c0031: 00000000 00000062 0000003d 0000006f .......b...=...o > => md.w fc0c0001 10 > fc0c0001: 0000 3701 0000 6f74 0000 643d 0000 6e20 ..7...ot..d=..n > fc0c0011: 0000 745f 0000 7300 0000 6f74 0000 6c61 ..t_..s...ot..la > > This commit implements a workaround at least for the most blatant > problem: using memcpy() from NOR flash. We rename the assembler > routine into __memcpy() and provide a wrapper, which will use a > byte-wise copy loop for unaligned source or target addresses when > reading from NOR flash, and branch to the optimized __memcpy() > in all other cases, thus minimizing the performance impact. > > Tested on lite5200b and TQM5200S. > > Signed-off-by: Wolfgang Denk <[email protected]> > Cc: Detlev Zundel <[email protected]> Acked-by: Detlev Zundel <[email protected]> [...] > diff --git a/arch/powerpc/cpu/mpc5xxx/memcpy_mpc5200.c > b/arch/powerpc/cpu/mpc5xxx/memcpy_mpc5200.c > new file mode 100644 > index 0000000..0950354 > --- /dev/null > +++ b/arch/powerpc/cpu/mpc5xxx/memcpy_mpc5200.c > @@ -0,0 +1,71 @@ > +/* > + * (C) Copyright 2010 > + * Wolfgang Denk, DENX Software Engineering, [email protected]. > + * > + * See file CREDITS for list of people who contributed to this > + * project. > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License as > + * published by the Free Software Foundation; either version 2 of > + * the License, or (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, write to the Free Software > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, > + * MA 02111-1307 USA > + */ > + > +/* > + * This is a workaround for issues on the MPC5200, where unaligned > + * 32-bit-accesses to the local bus will deliver corrupted data. This > + * happens for example when trying to use memcpy() from an odd NOR > + * flash address; the behaviour can be also seen when using "md" on an > + * odd NOR flash address (but there it is not a bug in U-Boot, which > + * only shows the behaviour of this processor). > + * > + * For memcpy(), we test if either the source or the target address > + * are not 32 bit aligned, and - if so - if the source address is in > + * NOR flash: in this case we perform a byte-wise (slow) then; for ^ +- copy > + * aligned operations of non-flash areas we use the optimized (fast) > + * real __memcpy(). This way we minimize the performance impact of > + * this workaround. > + * > + */ [...] Cheers Detlev -- WARNING: The external boundaries of India as depicted in map(s) are neither correct nor authentic. Other external boundaries as depicted in the map(s) may neither be correct nor authentic. -- Garmin MapSource manual -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: [email protected] _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
