Mark Lord wrote:

Tejun Heo wrote:

quoted

Hello, Mark.

Mark Lord wrote:

quoted

Tejun, I've added PMP to sata_mv, and am now trying to get it
to work with a Marvell PM attached.

And the behaviour I see is very bizarre.

After hard+soft resets, the PM signature is found,
and libata interrogates the PM registers.

It successfully reads register 0, and then register 1.
But all subsequent registers read out (incorrectly) as zeros.

..

Saeed has confirmed this behaviour with a SATA analyzer.
The Marvell port-multiplier apparently likes to see clean HOB
information when accessing PMP registers.

Since sata_mv uses PIO shadow register access, this doesn't happen
automatically, as it might in a more purely FIS-based driver (eg. ahci).

One way to fix this is to flag these commands with ATA_TFLAG_LBA48,
forcing libata to write out the HOB fields with known (zero) values.

Signed-off-by: Saeed Bishara <redacted>
Acked-by: Mark Lord <redacted>
---
 drivers/ata/libata-pmp.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-pmp.c b/drivers/ata/libata-pmp.c
index caef2bb..d91f509 100644
--- a/drivers/ata/libata-pmp.c
+++ b/drivers/ata/libata-pmp.c

@@ -35,7 +35,7 @@ static unsigned int sata_pmp_read(struct ata_link *link, int reg, u32 *r_val)
 	ata_tf_init(pmp_dev, &tf);
 	tf.command = ATA_CMD_PMP_READ;
 	tf.protocol = ATA_PROT_NODATA;
-	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE | ATA_TFLAG_LBA48;
 	tf.feature = reg;
 	tf.device = link->pmp;
 

@@ -71,7 +71,7 @@ static unsigned int sata_pmp_write(struct ata_link *link, int reg, u32 val)
 	ata_tf_init(pmp_dev, &tf);
 	tf.command = ATA_CMD_PMP_WRITE;
 	tf.protocol = ATA_PROT_NODATA;
-	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE | ATA_TFLAG_LBA48;
 	tf.feature = reg;
 	tf.device = link->pmp;
 	tf.nsect = val & 0xff;