[PATCH 1/5] ARM: s3c64xx: PM: Mask and acknowledge all UART interrupts during core resume.

From: kgene.kim@samsung.com (Kukjin Kim)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] ARM: s3c64xx: PM: Mask and acknowledge all UART interrupts during core resume.
Date: Fri, 19 Aug 2011 14:24:09 +0900	[thread overview]
Message-ID: <000901cc5e30$3a744000$af5cc000$%kim@samsung.com> (raw)
In-Reply-To: <1459034.DmseOOHbXX@flatron>

Tomasz Figa wrote:
> 
> On Friday 29 of July 2011 at 18:05:04, Tomasz Figa wrote:
> > From 9fd700af5b0c2289a09736a877f6047d1dcd3268 Mon Sep 17 00:00:00 2001
> > From: Tomasz Figa <tomasz.figa@gmail.com>
> > Date: Tue, 19 Jul 2011 22:21:41 +0200
> > Subject: [PATCH 1/5] ARM: s3c64xx: PM: Mask and acknowledge all UART
> >  interrupts during core resume.
> >
> > On some boards (in my case Tiny6410 from FriendlyARM), after waking up
from
> > sleep mode, UART controllers are left in an unclean state with interrupt
> > status bits set. After reenabling interrupts the system starts to get
> > hammered by infinite UART interrupts, which cannot be acknowledged,
because
> > of disabled UART bus clock. You can imagine the outcome.
> >
> > This patch deals with the issue by reenabling the bus clock in PCLK mask
> > temporarily, acknowledging and masking all the UART interrupts and then
> > restoring the original PCLK mask value, before interrupts get enabled.
> >
> > Alternatively, the issue could be avoided by moving all the UART
interrupt
> > handling to the S3C UART driver and disabling the IRQ on port suspend.
> > Could anyone explain me what is the benefit of having the UART IRQ
managed
> > by the generic IRQ infrastructure, while it is used only by a single
driver?
> >
> > ---
> >  arch/arm/mach-s3c64xx/pm.c |   26 ++++++++++++++++++++++++++
> >  1 files changed, 26 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/arm/mach-s3c64xx/pm.c b/arch/arm/mach-s3c64xx/pm.c
> > index bc1c470..799a212 100644
> > --- a/arch/arm/mach-s3c64xx/pm.c
> > +++ b/arch/arm/mach-s3c64xx/pm.c
> > @@ -16,12 +16,14 @@
> >  #include <linux/suspend.h>
> >  #include <linux/serial_core.h>
> >  #include <linux/io.h>
> > +#include <linux/delay.h>
> >
> >  #include <mach/map.h>
> >  #include <mach/irqs.h>
> >
> >  #include <plat/pm.h>
> >  #include <plat/wakeup-mask.h>
> > +#include <plat/regs-serial.h>
> >
> >  #include <mach/regs-sys.h>
> >  #include <mach/regs-gpio.h>
> > @@ -93,12 +95,36 @@ void s3c_pm_configure_extint(void)
> >
> >  void s3c_pm_restore_core(void)
> >  {
> > +	u32 pclkgate, tmp;
> > +	int i;
> > +
> >  	__raw_writel(0, S3C64XX_EINT_MASK);
> >
> >  	s3c_pm_debug_smdkled(1 << 2, 0);
> >
> >  	s3c_pm_do_restore_core(core_save, ARRAY_SIZE(core_save));
> >  	s3c_pm_do_restore(misc_save, ARRAY_SIZE(misc_save));
> > +
> > +	tmp = pclkgate = __raw_readl(S3C_PCLK_GATE);
> > +
> > +	/* re-start uart clocks */
> > +	tmp |= S3C_CLKCON_PCLK_UART0;
> > +	tmp |= S3C_CLKCON_PCLK_UART1;
> > +	tmp |= S3C_CLKCON_PCLK_UART2;
> > +	tmp |= S3C_CLKCON_PCLK_UART3;
> > +
> > +	__raw_writel(tmp, S3C_PCLK_GATE);
> > +
> > +	udelay(10);
> > +
> > +	for (i = 0; i < 4; ++i) {
> > +		__raw_writel(15, S3C_VA_UARTx(i) + S3C64XX_UINTM);
> > +		__raw_writel(15, S3C_VA_UARTx(i) + S3C64XX_UINTP);
> > +	}
> > +
> > +	udelay(10);
> > +
> > +	__raw_writel(pclkgate, S3C_PCLK_GATE);
> >  }
> >
> >  void s3c_pm_save_core(void)
> >
> 
> This should be fixed by
> 
> [PATCH 0/2] Update uart irq handling for s3c64xx and later SoC's
> by Thomas Abraham,
> 
> so I guess it is safe to drop my patch.
> 
OK.
Thanks.

Best regards,
Kgene.
--
Kukjin Kim <kgene.kim@samsung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.