Nyaaori/rockbox
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

FAT: align writes when bounce buffering is enabled

Browse source 
Motivation: turns out the DMA in the M3K's MSC controller is buggy,
and can't handle unaligned addresses properly despite the HW docs
claiming otherwise.

Extending the FAT driver bounce buffering code is the easiest way
to work around the problem (but probably not the most efficient).

Change-Id: I1b59b0eb4bbc881d317ff10c64ecadb1f9041236
This commit is contained in:
Aidan MacDonald 2021-05-13 15:29:02 +01:00
parent ff28d238b8
commit eb0336eded
1 changed files with 28 additions and 29 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

57
firmware/drivers/fat.c
View file

@ -2384,44 +2384,43 @@ static long transfer(struct bpb *fat_bpb, unsigned long start, long count,
panicf("Write %ld after data\n",
start + count - fat_bpb->totalsectors);
}
else
{
rc = storage_write_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, buf);
}
}
else
{
void* xferbuf = buf;
#ifdef STORAGE_NEEDS_BOUNCE_BUFFER
int remain = count;
int xferred = 0;
int aligned = 1;
if(STORAGE_OVERLAP((uintptr_t)buf)) {
xferbuf = FAT_BOUNCE_BUFFER(fat_bpb);
aligned = 0;
count = MIN(remain, FAT_BOUNCE_SECTORS);
}
while(remain > 0) {
#endif
rc = storage_read_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, xferbuf);
#ifdef STORAGE_NEEDS_BOUNCE_BUFFER
if(UNLIKELY(STORAGE_OVERLAP((uintptr_t)buf))) {
void* xfer_buf = FAT_BOUNCE_BUFFER(fat_bpb);
while(count > 0) {
int xfer_count = MIN(count, FAT_BOUNCE_SECTORS);
if(write) {
memcpy(xfer_buf, buf, xfer_count * SECTOR_SIZE);
rc = storage_write_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, xfer_count, xfer_buf);
} else {
rc = storage_read_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, xfer_count, xfer_buf);
memcpy(buf, xfer_buf, xfer_count * SECTOR_SIZE);
}
if(rc < 0)
break;
if(LIKELY(aligned))
break;
memcpy(buf, xferbuf, count * SECTOR_SIZE);
buf += count * SECTOR_SIZE;
xferred += count;
start += count;
remain -= count;
count = MIN(remain, FAT_BOUNCE_SECTORS);
buf += xfer_count * SECTOR_SIZE;
start += xfer_count;
count -= xfer_count;
}
} else {
#endif
if(write) {
rc = storage_write_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, buf);
} else {
rc = storage_read_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, buf);
}
#ifdef STORAGE_NEEDS_BOUNCE_BUFFER
}
#endif
if (rc < 0)
{