Patch "AHCI: Fix softreset failed issue of Port Multiplier" has been added to the 3.14-stable tree

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 3.14-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-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Xiangliang Yu <[email protected]>
Date: Thu, 26 Nov 2015 20:27:02 +0800
Subject: AHCI: Fix softreset failed issue of Port Multiplier

From: Xiangliang Yu <[email protected]>

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.

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

@@ -1253,6 +1253,15 @@ 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 [email protected] are

queue-3.14/ahci-fix-softreset-failed-issue-of-port-multiplier.patch