On Thu, Jul 8, 2010 at 8:38 AM, Steve Deiters <stevedeit...@basler.com> wrote: >> -----Original Message----- >> From: glik...@secretlab.ca [mailto:glik...@secretlab.ca] On >> Behalf Of Grant Likely >> Sent: Thursday, July 08, 2010 12:38 AM >> To: Benjamin Herrenschmidt >> Cc: Steve Deiters; linuxppc-dev@lists.ozlabs.org >> Subject: Re: [PATCH] arch/powerpc/lib/copy_32.S: Use >> alternate memcpy for MPC512x and MPC52xx >> >> On Wed, Jul 7, 2010 at 11:10 PM, Benjamin Herrenschmidt >> <b...@kernel.crashing.org> wrote: >> > On Tue, 2010-06-29 at 11:04 -0500, Steve Deiters wrote: >> >> These processors will corrupt data if accessing the local bus with >> >> unaligned addresses. This version fixes the typical case >> of copying >> >> from Flash on the local bus by keeping the source address always >> >> aligned. >> > >> > Shouldn't this be solved by using memcpy_to/fromio ? >> >> Maybe. plain memcpy() access to anything localbus-attached >> on the mpc5xxx is the wrong thing to do. memcpy_to/fromio >> might do the right thing; but the caller must understand the >> limitations of the localplus bus. The byte-wise alignment >> that memcpy_to/fromio() does may not work (depending on >> configuration). >> >> Steve, what code is doing a memcpy from flash? >> >> g. > > This was done in the JFFS2 code, in fs/jffs2/scan.c. At least in one > function, in jffs2_scan_dirent_node it was using memcpy on a localbus > mapped structure. I was getting JFFS2 filesystem corruption because of > this. In fact I first tried changing this to memcpy_fromio and it fixed > that particular problem. I was concerned though that other places I was > not aware of might be using memcpy from the localbus in a similar manner > so I decided to just tweak the memcpy routine.
[cc'ing David Woodhouse] Sounds to me like the right thing to do is to fix the jffs2 code. > Just out of curiousity, what configuration might cause a byte-wise > alignment not to work? Can't remember the register configuration, but I worked on one project where this was the case. In hindsight, it was probably a mis-configuration of the localbus CS for the particular device. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
