Hello.
Bartlomiej Zolnierkiewicz wrote:
We need to keep our kernel working on both legacy and modern hardware.
As it turned out, some boards don't have proper IDE DMA support for
CompactFlash (CF) adaptors, because pin connectors which relate to DMA are left
unsoldered (*).
To verify this we even bought external IDE CF adaptor which showed the same
symthoms, and then manually soldered pins that were left dangling, and voila,
DMA started to work!
Again, as they say, lots of manufacturers of not-so-new hardware did CF
soldering by the wrong way with respect to DMA, so we need a workaround.
For this __ide_dma_bad_drive function is enhance to check not only drives
blacklist but motherboards blacklist too.
Please apply before 2.6.29
(*) On IEI PCISA-C3/EDEN the kernel boots _very_ slowly, becuase we have lots
of DMA timer expiry:
<~30s pause>
hdc: dma_timer_epiry: dma_status == 0x21
hdc: DMA timeout error
...
hdc: DMA disabled
ide1: dma reset
<and the whole story repeats:>
<~30s pause>
hdc: dma_timer_epiry: dma_status == 0x21
...
Are you aware of ide_core.nodma= option which allows disabling DMA per
interface/drive? Read Documentation/ide/ide.txt please. I should note that
nodma option has been there for ages in one or other form.
While it can be workarounded manually using "ide_core.nodma" we should really
be aiming at ease of use for the end users and always let the code handle such
issues automatically if possible.
I'd agree. The patch didn't seem to provide an accpetable form of
such workaround though... although looks like I wasn't looking
attentively enough.
diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index fffd117..adb5d9d 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -33,6 +33,21 @@
#include <linux/ide.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
+#include <linux/dmi.h>
+
+/* Internal structure for blacklisted boards */
+struct board_blacklist_entry {
+ const char *board_vendor;
+ const char *board_name;
+ const char *drive_name;
+};
+
+/* Blacklisted boards which have problems with DMA */
+static const struct board_blacklist_entry board_blacklist[] = {
+ /* on IEI PCISA-C3 CF adapter pin connectors for DMA are missing */
+ { "FIC" , "PT-2200" , "hdc" },
I don't get it... FIC PT-2200 was Pentium class motherboard with
Intel's 430HX chipset not having CF slot at all (as googling for its
name has revealed). How it is connected to the (relatively modern)
PCISA-C3/EPIC board?! What are you trying to smuggle into kernel? :-) Or
this board just reports the bogus DMI IDs?
@@ -207,6 +222,30 @@ void ide_dma_on(ide_drive_t *drive)
drive->hwif->dma_ops->dma_host_set(drive, 1);
}
+static int __ide_dma_bad_adaptor(ide_drive_t *drive)
+{
+ const struct board_blacklist_entry *table = board_blacklist;
+
+ const char *board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
+ const char *board_name = dmi_get_system_info(DMI_BOARD_NAME);
+
+ if (!board_vendor || !board_name)
+ return 0;
+
+ for ( ; table->board_name ; table++)
+ if ((!strcmp(board_vendor, table->board_vendor)) &&
+ (!strcmp(board_name, table->board_name)) &&
+ (!strcmp(drive->name, table->drive_name))) {
+ printk(KERN_WARNING "%s: Disabling (U)DMA for %s "
+ "(Board %s %s is blacklisted)\n", drive->name,
+ (char *)&drive->id[ATA_ID_PROD], board_vendor,
+ board_name);
+ return 1;
+ }
+
+ return 0;
+}
+
This code doesn't anyhow discriminate the case of on-board CF and say
Hm, previously I failed to notice that the patch tries to
discriminate this case based on applying the workaround only to the
drive with certain name ("hdc"). However, it still seems wrong to place
this workaround in __ide_dma_bad_drive() as it's not actually connected
to the deficiency of a specific drive but to the definciency of the CF
slot itself. Moreover, depending on the PCI cards plugged, the drive's
name may change...
normal IDE PCI card plugged into such board -- with latter having no issues
And the PT-2200 board did have PCI and even ISA slots... oh wait,
that's really another board. :-) That EPIC board is PICMG however, so
can have a backplane with PCI slots.
with DMA whatsoever. E.g. AMD Geode GX2 dev. board (DB2301) has CF slot (with
unsoldered DMA pins, IIRC) and 3 PCI slots where you can plug a normal IDE card.
True. However it should be possible to handle it correctly by adding the
DMA quirk to the respective host drivers (seems to be via82cxxx.c in case of
IEI PCISA-C3/EDEN).
Yeah, this seems a viable approach...
Kirill, could you please look into adding such quirk to via82cxxx instead?
[ It seems the best place to add it would be via_init_one() as we could just
No, not really -- the issue is not at all as simple as this patch
tried to present it. Looking at its "Quick Startup Reference"
(http://f.ipc2u.ru/files/add/doc/496/M_PCISA-C800EV_ENG.pdf), the EPIC
board has *two* normal IDE connectors in addition to the CF slot
(connected to the secondary port -- and it seems possible that a hard
drive can be connected to the same port as CF), so the right place seems
to rather be in [mu]dma_filter() methods -- and the decision should be
strictly based on the drive type indicating CF, i.e. by calling
ata_id_is_cfa().
Sergei, care to handle AMD Geode GX2 case?
Eh... the DB2301 board I had on my desk for a long time died in my
hands 12/31, that same day when I NAKed this patch -- sort of NY
present/ :-) Well, actually it stopped to boot the BIOS several weeks
before that, then it just stopped to power up. We probably have another
one (not sure if it's alive still) but all MV's development work for
Geode GX2 stoped like 3 years ago. And now I'm not even sure that CF DMA
issue really existed there -- I wasn't directly involved with CF related
issues we had at the time of the active development, so my memory might
be wrong. What I can say for sure is that the CF slot on DB2301 board
coexisted with the normal IDE connector on CS5535's single channel and
both CF and hard disk worked simultaneously (if you were lucky :-). I'll
see if I have the board schematics from which I may be able to tell if
the issue really existed.
Thanks,
Bart
MBR, Sergei
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