[PATCH 4.2.y-ckt 034/273] libata: disable forced PORTS_IMPL for >= AHCI 1.3

From: Kamal Mostafa
Date: Mon Mar 07 2016 - 17:53:35 EST


4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Tejun Heo <tj@xxxxxxxxxx>

commit 566d1827df2ef0cbe921d3d6946ac3007b1a6938 upstream.

Some early controllers incorrectly reported zero ports in PORTS_IMPL
register and the ahci driver fabricates PORTS_IMPL from the number of
ports in those cases. This hasn't mattered but with the new nvme
controllers there are cases where zero PORTS_IMPL is valid and should
be honored.

Disable the workaround for >= AHCI 1.3.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/g/CALCETrU7yMvXEDhjAUShoHEhDwifJGapdw--BKxsP0jmjKGmRw@xxxxxxxxxxxxxx
Cc: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/ata/libahci.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 98c482a..317f85d 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -495,8 +495,8 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
}
}

- /* fabricate port_map from cap.nr_ports */
- if (!port_map) {
+ /* fabricate port_map from cap.nr_ports for < AHCI 1.3 */
+ if (!port_map && vers < 0x10300) {
port_map = (1 << ahci_nr_ports(cap)) - 1;
dev_warn(dev, "forcing PORTS_IMPL to 0x%x\n", port_map);

--
2.7.0