pata-macio on PowerBook G3: stuck interrupt with MATSHITA CR-174 CD-ROM

[Finn Thain]

On Fri, 28 Jun 2019, Finn Thain wrote:

> Hi All,
> 
> I've received a bug report concerning the pata-macio driver, when running 
> on a PowerBook G3 (Wallstreet).
> 
> With CONFIG_PATA_MACIO=n && CONFIG_BLK_DEV_IDE_PMAC=y, everything works.
> 
> With CONFIG_PATA_MACIO=y && CONFIG_BLK_DEV_IDE_PMAC=n, the CD-ROM fails.
> 
> When the CD-ROM mediabay module is swapped for a DVD-ROM mediabay module, 
> everything works (either pata-macio or ide-pmac driver works fine).
> 
> I'm not familiar with ATA device drivers or the "Heathrow" chipset and its 
> ATA interfaces so any hints as to how to debug this would be appreciated.
> 
...
> 
> These logs are from v4.20 but the problem is the same in v5.2-rc2.
> 

In the linux-ide list archive I found the same bug reported in 2.6.33-rc2, 
shortly after the pata-macio driver was merged.

https://lore.kernel.org/linux-ide/19254.17766.674348.933702@pilspetsen.it.uu.se/

That report also involves a Matshita CD-ROM and a Heathrow controller 
(beige G3).

In that thread Ben suggested that the cause may be a firmware bug in the 
drive. Is there a quirk or other workaround for that kind of bug?

I tried removing the controller reset but there was no improvement...

diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c
index 57f2ec71cfc3..b2fd5e20367f 100644
--- a/drivers/ata/pata_macio.c
+++ b/drivers/ata/pata_macio.c
@@ -1096,7 +1096,7 @@ static int pata_macio_common_init(struct pata_macio_priv *priv,
 	priv->host->ports[0]->private_data = priv;
 
 	/* hard-reset the controller */
-	pata_macio_reset_hw(priv, 0);
+//	pata_macio_reset_hw(priv, 0);
 	pata_macio_apply_timings(priv->host->ports[0], 0);
 
 	/* Enable bus master if necessary */

--