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Commit 7db143b8 authored by Tony Lindgren's avatar Tony Lindgren
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ARM: OMAP3: Fix I/O chain clock line assertion timed out error 



We are getting "PRM: I/O chain clock line assertion timed out" errors
on early omaps for device tree based booting. This is because we are
unconditionally calling reconfigure_io_chain while legacy booting
has omap3_has_io_chain_ctrl() checks in place in omap_hwmod.c.

For device tree based booting, we are calling reconfigure_io_chain
unconditionally from pinctrl framework. So we need to add a check for
omap3_has_io_chain_ctrl() to avoid the errors for trying to access
a register that does not exist.

For es3.0, the documentation in "4.11.2 Device Off-Mode Configuration"
just mentions PM_WKEN_WKUP[8] bit. For es3.1, there's a new chapter in
documentation for "4.11.2.2 I/O Wake-Up Mechanism" that describes the
PM_WKEN_WKUP[16] ST_IO_CHAIN bit. So PM_WKEN_WKUP[16] bit did not get
added until in es3.1 probaly to fix issues with flakey wake-up events.

We are doing proper checks for ST_IO_CHAIN already in id.c and with
omap3_has_io_chain_ctrl(). For more information, see also commit
b02b9172 ("ARM: OMAP3: PM: fix I/O wakeup and I/O chain clock
control detection").

Let's fix the issue by selecting the right function during init for
reconfigure_io_chain depending on the omap revision. For es3.0 and
earlier we need to just toggle EN_IO. By doing this, we can move the
check for omap3_has_io_chain_ctrl() from omap_hwmod.c to the init code
in prm_3xxx.c. And then we can unconditionally call reconfigure_io_chain.

Thanks to Paul Walmsley and Nishanth Menon for help with debugging the
issue.

Fixes: 30a69ef7 ("ARM: OMAP: Move DT wake-up event handling over to use pinctrl-single-omap")
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Reviewed-by: default avatarNishanth Menon <nm@ti.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
parent 69e273c0

arch/arm/mach-omap2/omap_hwmod.c

+1 −1
Original line number Diff line number Diff line
@@ -2065,7 +2065,7 @@ static void _reconfigure_io_chain(void) 


	spin_lock_irqsave(&io_chain_lock, flags);



	if (cpu_is_omap34xx() && omap3_has_io_chain_ctrl())

	if (cpu_is_omap34xx())

		omap3xxx_prm_reconfigure_io_chain();

	else if (cpu_is_omap44xx())

		omap44xx_prm_reconfigure_io_chain();

arch/arm/mach-omap2/prm3xxx.c

+35 −4
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static struct omap_prcm_irq_setup omap3_prcm_irq_setup = { 
	.ocp_barrier		= &omap3xxx_prm_ocp_barrier,

	.save_and_clear_irqen	= &omap3xxx_prm_save_and_clear_irqen,

	.restore_irqen		= &omap3xxx_prm_restore_irqen,

	.reconfigure_io_chain	= &omap3xxx_prm_reconfigure_io_chain,

	.reconfigure_io_chain	= NULL,

};



/*
@@ -369,15 +369,30 @@ void __init omap3_prm_init_pm(bool has_uart4, bool has_iva) 
}



/**

 * omap3xxx_prm_reconfigure_io_chain - clear latches and reconfigure I/O chain

 * omap3430_pre_es3_1_reconfigure_io_chain - restart wake-up daisy chain

 *

 * The ST_IO_CHAIN bit does not exist in 3430 before es3.1. The only

 * thing we can do is toggle EN_IO bit for earlier omaps.

 */

void omap3430_pre_es3_1_reconfigure_io_chain(void)

{

	omap2_prm_clear_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,

				     PM_WKEN);

	omap2_prm_set_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,

				   PM_WKEN);

	omap2_prm_read_mod_reg(WKUP_MOD, PM_WKEN);

}



/**

 * omap3_prm_reconfigure_io_chain - clear latches and reconfigure I/O chain

 *

 * Clear any previously-latched I/O wakeup events and ensure that the

 * I/O wakeup gates are aligned with the current mux settings.  Works

 * by asserting WUCLKIN, waiting for WUCLKOUT to be asserted, and then

 * deasserting WUCLKIN and clearing the ST_IO_CHAIN WKST bit.  No

 * return value.

 * return value. These registers are only available in 3430 es3.1 and later.

 */

void omap3xxx_prm_reconfigure_io_chain(void)

void omap3_prm_reconfigure_io_chain(void)

{

	int i = 0;
@@ -399,6 +414,15 @@ void omap3xxx_prm_reconfigure_io_chain(void) 
	omap2_prm_read_mod_reg(WKUP_MOD, PM_WKST);

}



/**

 * omap3xxx_prm_reconfigure_io_chain - reconfigure I/O chain

 */

void omap3xxx_prm_reconfigure_io_chain(void)

{

	if (omap3_prcm_irq_setup.reconfigure_io_chain)

		omap3_prcm_irq_setup.reconfigure_io_chain();

}



/**

 * omap3xxx_prm_enable_io_wakeup - enable wakeup events from I/O wakeup latches

 *
@@ -656,6 +680,13 @@ static int omap3xxx_prm_late_init(void) 
	if (!(prm_features & PRM_HAS_IO_WAKEUP))

		return 0;



	if (omap3_has_io_chain_ctrl())

		omap3_prcm_irq_setup.reconfigure_io_chain =

			omap3_prm_reconfigure_io_chain;

	else

		omap3_prcm_irq_setup.reconfigure_io_chain =

			omap3430_pre_es3_1_reconfigure_io_chain;



	omap3xxx_prm_enable_io_wakeup();

	ret = omap_prcm_register_chain_handler(&omap3_prcm_irq_setup);

	if (!ret)