3.19.8-ckt16 -stable review patch.  If anyone has any objections, please let me 
know.

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

From: Tejun Heo <t...@kernel.org>

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 <t...@kernel.org>
Reported-by: Andy Lutomirski <l...@amacapital.net>
Link: 
http://lkml.kernel.org/g/calcetru7ymvxedhjaushohehdwifjgapdw--bkxsp0jmjkg...@mail.gmail.com
Cc: Sergei Shtylyov <sergei.shtyl...@cogentembedded.com>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
 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 902dcfa..b0144e9 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

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