Date: Mon, 20 Apr 1998 21:36:41 +0800 From: Peter Wemm <peter@netplex.com.au> To: gibbs@FreeBSD.ORG Cc: scsi@FreeBSD.ORG Subject: New CAM w/ buslogic doesn't do bounce buffers correctly.. Message-ID: <199804201336.VAA04663@spinner.netplex.com.au>
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It seems that when bt_ccb's are allocated, the dmamap pointer isn't
initialized, so it stays null. This causes a few things to hit a fatal
trap at first call since map == NULL isn't checked in a few critical
places (bus_dmamap_load for starters). add_bounce_page() doesn;'t work if
the map = NULL -> map = &nobounce_dmamap conversion happens since the
bpages SLIST isn't initialized there either.
dev/buslogic/bt.c:
segs = sg_map->sg_vaddr;
physaddr = sg_map->sg_physaddr;
newcount = (PAGE_SIZE / (BT_NSEG * sizeof(bt_sg_t)));
for (i = 0; bt->num_ccbs < bt->max_ccbs && i < newcount; i++) {
next_ccb->sg_list = segs;
next_ccb->sg_list_phys = physaddr;
next_ccb->flags = BCCB_FREE;
>> what about next_ccb->dmamap??
SLIST_INSERT_HEAD(&bt->free_bt_ccbs, next_ccb, links);
segs += BT_NSEG;
physaddr += (BT_NSEG * sizeof(bt_sg_t));
next_ccb++;
bt->num_ccbs++;
}
At a guess, it should be set pointing to the instance of the
containing page's sg->sg_dmamap. so, perhaps
+ new_ccb->dmamap = sg->sg_dmamap?
And then there's this:
int
bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
bus_size_t buflen, bus_dmamap_callback_t *callback,
void *callback_arg, int flags)
{
[..]
if (dmat->lowaddr < ptoa(Maxmem) && map->pagesneeded == 0) {
[..]
}
if (map == NULL)
map = &nobounce_dmamap;
[later]
do {
[..]
if (map->pagesneeded != 0 && run_filter(dmat, paddr)) {
paddr = add_bounce_page(dmat, map, vaddr, size);
}
[..]
And add_bounce_page() does:
[..]
bpage->datavaddr = vaddr;
bpage->datacount = size;
STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
return (bpage->busaddr);
}
In the instance where map = &nobounce_dmamap, the STAILQ_INSERT_TAIL()
faults since the bpages list is never intialised.
If the map = NULL stuff isn't really needed (or I'm sure the
bus_dmamap_load stuff would have been noticed by now :-), then perhaps
it's just some bit-rot that needs to be trimmed.
Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au> Netplex Consulting
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