linux-kernel - [PATCH 4.14 063/165] usb: host: xhci-plat: revert "usb: host: xhci-plat: enable clk in resume timing"

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Date:   Thu, 24 May 2018 11:37:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 063/165] usb: host: xhci-plat: revert "usb: host: xhci-plat: enable clk in resume timing"

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

------------------

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>

[ Upstream commit d56e57ca030c8b4296944a2ae61ac167bf979c07 ]

This patch reverts the commit 835e4241e714 ("usb: host: xhci-plat:
enable clk in resume timing") because this driver also has runtime PM
and the commit 560869100b99 ("clk: renesas: cpg-mssr: Restore module
clocks during resume") will restore the clock on R-Car H3 environment.

If the xhci_plat_suspend() disables the clk, the system cannot enable
the clk in resume like the following behavior:

< In resume >
 - genpd_resume_noirq() runs and enable the clk (enable_count = 1)
 - cpg_mssr_resume_noirq() restores the clk register.
  -- Since the clk was disabled in suspend, cpg_mssr_resume_noirq()
     will disable the clk and keep the enable_count.
 - Even if xhci_plat_resume() calls clk_prepare_enable(), since
   the enable_count is 1, the clk will be not enabled.

After this patch is applied, the cpg-mssr driver will save the clk
as enable, so the clk will be enabled in resume.

Fixes: 835e4241e714 ("usb: host: xhci-plat: enable clk in resume timing")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/usb/host/xhci-plat.c |   11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -355,7 +355,6 @@ static int __maybe_unused xhci_plat_susp
 {
 	struct usb_hcd	*hcd = dev_get_drvdata(dev);
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
-	int ret;
 
 	/*
 	 * xhci_suspend() needs `do_wakeup` to know whether host is allowed
@@ -365,12 +364,7 @@ static int __maybe_unused xhci_plat_susp
 	 * reconsider this when xhci_plat_suspend enlarges its scope, e.g.,
 	 * also applies to runtime suspend.
 	 */
-	ret = xhci_suspend(xhci, device_may_wakeup(dev));
-
-	if (!device_may_wakeup(dev) && !IS_ERR(xhci->clk))
-		clk_disable_unprepare(xhci->clk);
-
-	return ret;
+	return xhci_suspend(xhci, device_may_wakeup(dev));
 }
 
 static int __maybe_unused xhci_plat_resume(struct device *dev)
@@ -379,9 +373,6 @@ static int __maybe_unused xhci_plat_resu
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 	int ret;
 
-	if (!device_may_wakeup(dev) && !IS_ERR(xhci->clk))
-		clk_prepare_enable(xhci->clk);
-
 	ret = xhci_priv_resume_quirk(hcd);
 	if (ret)
 		return ret;