| Message ID | 1320224323.294130.1342735357081.JavaMail.root@advansee.com |
|---|---|
| State | Superseded |
| Headers | show |
On Thursday 19 July 2012 18:02:37 Benoît Thébaudeau wrote: > + if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) { > ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size); > > + debug("FAT: Misaligned buffer address (%p)\n", buffer); i'd suggest making this a printf. bounce buffers are not cheap. -mike
On Friday 20 July 2012 00:48:26 Mike Frysinger wrote: > On Thursday 19 July 2012 18:02:37 Benoît Thébaudeau wrote: > > + if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) { > > ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size); > > > > + debug("FAT: Misaligned buffer address (%p)\n", buffer); > > i'd suggest making this a printf. OK. I chose debug to do like mmc.c. I'll switch to printf if you prefer. However, debug is better here IMHO to avoid visual pollution on stdout because this bouncing can still occur in normal conditions with perfectly aligned buffers, in the case data is read from an unaligned position relative to the file to an aligned offset relative to the buffer. This can be avoided by improving the file format by aligning its data structures, but one can not always change a file format. debug would allow to detect misaligned buffers or to optimize file formats while not being bothering for the compelled file formats containing misaligned data structures. > bounce buffers are not cheap. Indeed. Anything else before I post a v2 of the series? Regards, Benoît
diff --git u-boot-66714b1.orig/fs/fat/fat.c u-boot-66714b1/fs/fat/fat.c index 943cdb6..4c80820 100644 --- u-boot-66714b1.orig/fs/fat/fat.c +++ u-boot-66714b1/fs/fat/fat.c @@ -274,7 +274,6 @@ get_cluster (fsdata *mydata, __u32 clustnum, __u8 *buffer, { __u32 idx = 0; __u32 startsect; - __u32 nr_sect; int ret; if (clustnum > 0) { @@ -286,25 +285,44 @@ get_cluster (fsdata *mydata, __u32 clustnum, __u8 *buffer, debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect); - nr_sect = size / mydata->sect_size; - ret = disk_read(startsect, nr_sect, buffer); - if (ret != nr_sect) { - debug("Error reading data (got %d)\n", ret); - return -1; - } - if (size % mydata->sect_size) { + if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) { ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size); + debug("FAT: Misaligned buffer address (%p)\n", buffer); + + while (size >= mydata->sect_size) { + ret = disk_read(startsect++, 1, tmpbuf); + if (ret != 1) { + debug("Error reading data (got %d)\n", ret); + return -1; + } + + memcpy(buffer, tmpbuf, mydata->sect_size); + buffer += mydata->sect_size; + size -= mydata->sect_size; + } + } else { idx = size / mydata->sect_size; - ret = disk_read(startsect + idx, 1, tmpbuf); + ret = disk_read(startsect, idx, buffer); + if (ret != idx) { + debug("Error reading data (got %d)\n", ret); + return -1; + } + startsect += idx; + idx *= mydata->sect_size; + buffer += idx; + size -= idx; + } + if (size) { + ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size); + + ret = disk_read(startsect, 1, tmpbuf); if (ret != 1) { debug("Error reading data (got %d)\n", ret); return -1; } - buffer += idx * mydata->sect_size; - memcpy(buffer, tmpbuf, size % mydata->sect_size); - return 0; + memcpy(buffer, tmpbuf, size); } return 0;
Add a buffer bouncing mechanism to get_cluster. This can be useful for misaligned applicative buffers passed through get_contents. This is required for the following patches in the case of data aligned differently relatively to buffers and clusters. Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com> Cc: Wolfgang Denk <wd@denx.de> --- .../fs/fat/fat.c | 42 ++++++++++++++------ 1 file changed, 30 insertions(+), 12 deletions(-)