[PATCH] ARM: OMAP2: UART: fix console UART mismatched runtime PM status

Kevin Hilman khilman at deeprootsystems.com
Mon Oct 15 19:49:58 EDT 2012

From: Kevin Hilman <khilman at ti.com>

The runtime PM framework assumes that the hardware state of devices
when initialized is disabled.  For all omap_devices, we idle/disable
device by default.  However, the console uart uses a "no idle" option
during omap_device init in order to allow earlyprintk usage to work
seamlessly during boot.

Because the hardware is left partially enabled after init (whatever
the bootloader settings were), the omap_device should later be fully
initialized (including mux) and the runtime PM framework should be
told that the device is active, and not disabled so that the hardware
state is in sync with runtime PM state.

To fix, after the device has been created/registered, call
omap_device_enable() to finialize init and use pm_runtime_set_active()
to tell the runtime PM core the device is enabled.

Tested on 2420/n810, 3530/Overo, 3530/Beagle, 3730/OveroSTORM,
3730/Beagle-xM, 4460/PandaES.

Reported-by: Paul Walmsley <paul at pwsan.com>
Suggested-by: Russell King <rmk+kernel at arm.linux.org.uk>
Cc: Felipe Balbi <balbi at ti.com>
Cc: Sourav Poddar <sourav.poddar at ti.com>
Signed-off-by: Kevin Hilman <khilman at ti.com>
Applies against v3.7-rc1.
Fix targetted for v3.7.

I'm still not entirely sure why this has worked up to now on OMAP3/4
but not on OMAP2.  Even so, this fix is needed for all platforms to
ensure matching hardware state and runtime PM state.

 arch/arm/mach-omap2/serial.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 0405c81..37b5dbe 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -327,6 +327,11 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
 	if ((console_uart_id == bdata->id) && no_console_suspend)
+	if (console_uart_id == bdata->id) {
+		omap_device_enable(pdev);
+		pm_runtime_set_active(&pdev->dev);
+	}
 	oh->mux = omap_hwmod_mux_init(bdata->pads, bdata->pads_cnt);
 	oh->dev_attr = uart;

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