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SubjectRe: [BUG] pnpbios breaks floppy support
Date
On Sunday 01 February 2009 11:43:31 pm Adam M Belay wrote:
> >>>>> $ cat 00:03/resources
> >>>>> state = active
> >>>>> io 0x3f4-0x3f5
> >>>>> io 0x3f2-0x3f2

> >> $ cat 00:07/id 00:07/resources
> >> PNP0c02
> >> state = active
> >> io 0x80-0x80
> >> io 0x10-0x1f
> >> io 0x22-0x3f
> >> io 0x44-0x5f
> >> io 0x90-0x9f
> >> io 0xa2-0xbf
> >> io 0x3f0-0x3f1
> >> io 0x3f3-0x3f3

> Ok, so it appears that we have a genuine resource conflict with the
> system device (00:07). This is because the floppy driver is requesting
> four consecutive I/O ports rather than the two ports reported by the
> PnPBIOS.

As far as I can tell, floppy.c uses only these registers:
0x3f2 (FD_DOR)
0x3f4 (FD_STATUS)
0x3f5 (FD_DATA)
0x3f7 (FD_DCR/FD_DIR)

But it requests 0x3f2-0x3f5 and 0x3f7. That includes the unused
register at 0x3f3, hence the conflict with 00:07.

I think we should just change floppy.c to request only ports
2, 4-5, and 7, with something like the patch below. Philippe,
can you give it a try?

> Bjorn, I think it might make sense to eventually have the PnP layer
> register resources with request_region() instead of handling it in
> device drivers. What do you think? In the short term we could either
> skip the floppy driver's call to request_region() when using PnP detection
> or have it use the length reported in the resource descriptor. Still, I'm
> curious which I/O ports the driver is actually using.

In PCI, we do both: the core requests resources based on the BAR values,
and the drivers request the actual resources they need. I think that's
important because we account for the resources used by devices without
drivers.

I would really like the PNP core to do something similar eventually.
We actually tried it a year or so ago in the -mm tree, but there are
some subtleties that I didn't fully comprehend, so we had to back it
out. Here are some of the threads from that attempt:

http://lkml.org/lkml/2007/10/29/412 (RFC)
http://lkml.org/lkml/2007/11/1/214 (repost)
http://lkml.org/lkml/2007/11/29/451 (suspend/resume problem)
http://lkml.org/lkml/2007/12/5/227 (more suspend/resume fiddling)
http://lkml.org/lkml/2007/12/11/200 (causes critical temp shutdown)

Bjorn


diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index cf29cc4..44f711b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4399,15 +4399,20 @@ static int floppy_grab_irq_and_dma(void)

for (fdc = 0; fdc < N_FDC; fdc++) {
if (FDCS->address != -1) {
- if (!request_region(FDCS->address + 2, 4, "floppy")) {
+ if (!request_region(FDCS->address + 2, 1, "floppy")) {
DPRINT("Floppy io-port 0x%04lx in use\n",
FDCS->address + 2);
goto cleanup1;
}
+ if (!request_region(FDCS->address + 4, 2, "floppy")) {
+ DPRINT("Floppy io-port 0x%04lx in use\n",
+ FDCS->address + 4);
+ goto cleanup2;
+ }
if (!request_region(FDCS->address + 7, 1, "floppy DIR")) {
DPRINT("Floppy io-port 0x%04lx in use\n",
FDCS->address + 7);
- goto cleanup2;
+ goto cleanup3;
}
/* address + 6 is reserved, and may be taken by IDE.
* Unfortunately, Adaptec doesn't know this :-(, */
@@ -4432,13 +4437,16 @@ static int floppy_grab_irq_and_dma(void)
fdc = 0;
irqdma_allocated = 1;
return 0;
+cleanup3:
+ release_region(FDCS->address + 4, 2);
cleanup2:
- release_region(FDCS->address + 2, 4);
+ release_region(FDCS->address + 2, 1);
cleanup1:
fd_free_irq();
fd_free_dma();
while (--fdc >= 0) {
- release_region(FDCS->address + 2, 4);
+ release_region(FDCS->address + 2, 1);
+ release_region(FDCS->address + 4, 2);
release_region(FDCS->address + 7, 1);
}
spin_lock_irqsave(&floppy_usage_lock, flags);

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