[PATCH 3/4] pata_parport: add custom version of wait_after_reset

Ondrej Zary
2023-09-30T19:18:10Z

Some parallel adapters (e.g. EXP Computer MC-1285B EPP Cable) return
bogus values when there's no master device present. This can cause
reset to fail, preventing the lone slave device (such as EXP Computer
CD-865) from working.

Add custom version of wait_after_reset that ignores master failure when
a slave device is present. The custom version is also needed because
the generic ata_sff_wait_after_reset uses direct port I/O for slave
device detection.

Signed-off-by: Ondrej Zary <linux@zary.sk>
---
drivers/ata/pata_parport/pata_parport.c | 65 ++++++++++++++++++++++++-
1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/pata_parport/pata_parport.c b/drivers/ata/pata_parport/pata_parport.c
index cf87bbb52f1f..b3db953e615a 100644
--- a/drivers/ata/pata_parport/pata_parport.c
+++ b/drivers/ata/pata_parport/pata_parport.c
@@ -80,6 +80,69 @@ static bool pata_parport_devchk(struct ata_port *ap, unsigned int device)
return (nsect == 0x55) && (lbal == 0xaa);
}

+static int pata_parport_wait_after_reset(struct ata_link *link,
+ unsigned int devmask,
+ unsigned long deadline)
+{
+ struct ata_port *ap = link->ap;
+ struct pi_adapter *pi = ap->host->private_data;
+ unsigned int dev0 = devmask & (1 << 0);
+ unsigned int dev1 = devmask & (1 << 1);
+ int rc, ret = 0;
+
+ ata_msleep(ap, ATA_WAIT_AFTER_RESET);
+
+ /* always check readiness of the master device */
+ rc = ata_sff_wait_ready(link, deadline);
+ /* some adapters return bogus values if master device is not present,
+ * so don't abort now if a slave device is present
+ */
+ if (rc) {
+ if (!dev1)
+ return rc;
+ ret = -ENODEV;
+ }
+
+ /* if device 1 was found in ata_devchk, wait for register
+ * access briefly, then wait for BSY to clear.
+ */
+ if (dev1) {
+ int i;
+
+ pata_parport_dev_select(ap, 1);
+
+ /* Wait for register access. Some ATAPI devices fail
+ * to set nsect/lbal after reset, so don't waste too
+ * much time on it. We're gonna wait for !BSY anyway.
+ */
+ for (i = 0; i < 2; i++) {
+ u8 nsect, lbal;
+
+ nsect = pi->proto->read_regr(pi, 0, ATA_REG_NSECT);
+ lbal = pi->proto->read_regr(pi, 0, ATA_REG_LBAL);
+ if ((nsect == 1) && (lbal == 1))
+ break;
+ ata_msleep(ap, 50); /* give drive a breather */
+ }
+
+ rc = ata_sff_wait_ready(link, deadline);
+ if (rc) {
+ if (rc != -ENODEV)
+ return rc;
+ ret = rc;
+ }
+ }
+
+ /* is all this really necessary? */
+ pata_parport_dev_select(ap, 0);
+ if (dev1)
+ pata_parport_dev_select(ap, 1);
+ if (dev0)
+ pata_parport_dev_select(ap, 0);
+
+ return ret;
+}
+
static int pata_parport_bus_softreset(struct ata_port *ap, unsigned int devmask,
unsigned long deadline)
{
@@ -94,7 +157,7 @@ static int pata_parport_bus_softreset(struct ata_port *ap, unsigned int devmask,
ap->last_ctl = ap->ctl;

/* wait the port to become ready */
- return ata_sff_wait_after_reset(&ap->link, devmask, deadline);
+ return pata_parport_wait_after_reset(&ap->link, devmask, deadline);
}

static int pata_parport_softreset(struct ata_link *link, unsigned int *classes,
--
Ondrej Zary