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

From: [email-masked] (Tomasz Figa)
Date: Sat, 13 Aug 2011 13:44:52 +0200

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 <[email-masked]>
> 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.

Best regards,
Tom