Patch "AHCI: Fix softreset failed issue of Port Multiplier" has been added to the 4.3-stable tree

Patch "AHCI: Fix softreset failed issue of Port Multiplier" has been added to the 4.3-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    AHCI: Fix softreset failed issue of Port Multiplier

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ahci-fix-softreset-failed-issue-of-port-multiplier.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 023113d24ef9e1d2b44cb2446872b17e2b01d8b1 Mon Sep 17 00:00:00 2001
From: Xiangliang Yu <Xiangliang.Yu@amd.com>
Date: Thu, 26 Nov 2015 20:27:02 +0800
Subject: AHCI: Fix softreset failed issue of Port Multiplier

From: Xiangliang Yu <Xiangliang.Yu@amd.com>

commit 023113d24ef9e1d2b44cb2446872b17e2b01d8b1 upstream.

Current code doesn't update port value of Port Multiplier(PM) when
sending FIS of softreset to device, command will fail if FBS is
enabled.

There are two ways to fix the issue: the first is to disable FBS
before sending softreset command to PM device and the second is
to update port value of PM when sending command.

For the first way, i can't find any related rule in AHCI Spec. The
second way can avoid disabling FBS and has better performance.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/ata/libahci.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1266,6 +1266,15 @@ static int ahci_exec_polled_cmd(struct a
 	ata_tf_to_fis(tf, pmp, is_cmd, fis);
 	ahci_fill_cmd_slot(pp, 0, cmd_fis_len | flags | (pmp << 12));
 
+	/* set port value for softreset of Port Multiplier */
+	if (pp->fbs_enabled && pp->fbs_last_dev != pmp) {
+		tmp = readl(port_mmio + PORT_FBS);
+		tmp &= ~(PORT_FBS_DEV_MASK | PORT_FBS_DEC);
+		tmp |= pmp << PORT_FBS_DEV_OFFSET;
+		writel(tmp, port_mmio + PORT_FBS);
+		pp->fbs_last_dev = pmp;
+	}
+
 	/* issue & wait */
 	writel(1, port_mmio + PORT_CMD_ISSUE);
 


Patches currently in stable-queue which might be from Xiangliang.Yu@amd.com are

queue-4.3/ahci-fix-softreset-failed-issue-of-port-multiplier.patch