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    DateThu, 30 Jun 2005 10:00:24 +0200
    FromPierre Ossman <>
    SubjectRe: ISA DMA controller hangs
    Reset the ISA DMA controller into a known state after a suspend. Primary
    concern was reenabling the cascading DMA channel (4).
    
    Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
    
    If this patch seems ok then I'll make another one for x86_64 (the only
    other platform with ISA DMA AFAIK).
    
    I couldn't find who was responsible for the i386 arch so I've cc:ed Linus.
    
    Rgds
    Pierre
    
    Index: linux-wbsd/arch/i386/kernel/i8237.c
    ===================================================================
    --- linux-wbsd/arch/i386/kernel/i8237.c	(revision 0)
    +++ linux-wbsd/arch/i386/kernel/i8237.c	(revision 0)
    @@ -0,0 +1,67 @@
    +/*
    + * i8237.c: 8237A DMA controller suspend functions.
    + *
    + * Written by Pierre Ossman, 2005.
    + */
    +
    +#include <linux/init.h>
    +#include <linux/sysdev.h>
    +
    +#include <asm/dma.h>
    +
    +/*
    + * This module just handles suspend/resume issues with the
    + * 8237A DMA controller (used for ISA and LPC).
    + * Allocation is handled in kernel/dma.c and normal usage is
    + * in asm/dma.h.
    + */
    +
    +static int i8237A_resume(struct sys_device *dev)
    +{
    +	unsigned long flags;
    +	int i;
    +	
    +	flags = claim_dma_lock();
    +	
    +	dma_outb(DMA1_RESET_REG, 0);
    +	dma_outb(DMA2_RESET_REG, 0);
    +
    +	for (i = 0;i < 8;i++) {
    +	  set_dma_addr(i, 0x000000);
    +	  /* DMA count is a bit wierd so this is not 0 */
    +	  set_dma_count(i, 1);
    +	}
    +	
    +	/* Enable cascade DMA or channel 0-3 won't work */
    +	enable_dma(4);
    +	
    +	release_dma_lock(flags);
    +	
    +	return 0;
    +}
    +
    +static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
    +{
    +	return 0;
    +}
    +
    +static struct sysdev_class i8237_sysdev_class = {
    +	set_kset_name("i8237"),
    +	.suspend = i8237A_suspend,
    +	.resume = i8237A_resume,
    +};
    +
    +static struct sys_device device_i8237A = {
    +	.id	= 0,
    +	.cls	= &i8237_sysdev_class,
    +};
    +
    +static int __init i8237A_init_sysfs(void)
    +{
    +	int error = sysdev_class_register(&i8237_sysdev_class);
    +	if (!error)
    +		error = sysdev_register(&device_i8237A);
    +	return error;
    +}
    +
    +device_initcall(i8237A_init_sysfs);
    Index: linux-wbsd/arch/i386/kernel/Makefile
    ===================================================================
    --- linux-wbsd/arch/i386/kernel/Makefile	(revision 153)
    +++ linux-wbsd/arch/i386/kernel/Makefile	(working copy)
    @@ -7,7 +7,7 @@
     obj-y	:= process.o semaphore.o signal.o entry.o traps.o irq.o vm86.o \
     		ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \
     		pci-dma.o i386_ksyms.o i387.o dmi_scan.o bootflag.o \
    -		doublefault.o quirks.o
    +		doublefault.o quirks.o i8237.o
     
     obj-y				+= cpu/
     obj-y				+= timers/
    \
     
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