DIPM is unsupported or broken on sunxi. Trying to enable the power
management policy med_power_with_dipm on an Allwinner A20 SoC based board
leads to immediate I/O errors and the attached SATA disk disappears from
the /dev filesystem. A reset (power cycle) is required to make the SATA
controller or disk work again. The A10 and A20 SoC data sheets and manuals
don't mention DIPM at all [1], so it's fair to assume that it's simply not
supported. But even if it was, it should be considered broken and best be
disabled in the ahci_sunxi driver.

[1] https://github.com/allwinner-zh/documents/tree/master/

Fixes: c5754b5220f0 ("ARM: sunxi: Add support for Allwinner SUNXi SoCs sata to ahci_platform")
Cc: stable@vger.kernel.org
Signed-off-by: Timo Sigurdsson <redacted>
Tested-by: Timo Sigurdsson <redacted>
---
Changes since v1:

- Formal changes to the commit message as suggested by Greg Kroah-Hartman
  and Sergei Shtylyov (Fixes and Cc lines). No changes to the patch
  itself.
---
 drivers/ata/ahci_sunxi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ata/ahci_sunxi.c b/drivers/ata/ahci_sunxi.c
index cb69b737cb49..56b695136977 100644
--- a/drivers/ata/ahci_sunxi.c
+++ b/drivers/ata/ahci_sunxi.c

@@ -200,7 +200,7 @@ static void ahci_sunxi_start_engine(struct ata_port *ap)
 }
 
 static const struct ata_port_info ahci_sunxi_port_info = {
-	.flags		= AHCI_FLAG_COMMON | ATA_FLAG_NCQ,
+	.flags		= AHCI_FLAG_COMMON | ATA_FLAG_NCQ | ATA_FLAG_NO_DIPM,
 	.pio_mask	= ATA_PIO4,
 	.udma_mask	= ATA_UDMA6,
 	.port_ops	= &ahci_platform_ops,

-- 
2.26.2


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