* ISA DMA controller hangs @ 2005-05-28 13:38 Pierre Ossman 2005-05-28 13:51 ` Alan Cox 0 siblings, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-05-28 13:38 UTC (permalink / raw) To: LKML I've been having some problems with ISA DMA transfers failing. They work fine until the machine does a suspend-to-ram. After that all DMA transfers stall. Does perhaps the DMA controller need a kick in the *** after a suspend? I'm no expert on the ISA DMA controller so I could use some help here. Rgds Pierre ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-05-28 13:38 ISA DMA controller hangs Pierre Ossman @ 2005-05-28 13:51 ` Alan Cox 2005-06-05 8:21 ` Pierre Ossman 0 siblings, 1 reply; 13+ messages in thread From: Alan Cox @ 2005-05-28 13:51 UTC (permalink / raw) To: Pierre Ossman; +Cc: LKML On Sad, 2005-05-28 at 14:38, Pierre Ossman wrote: > I've been having some problems with ISA DMA transfers failing. They work > fine until the machine does a suspend-to-ram. After that all DMA > transfers stall. Does perhaps the DMA controller need a kick in the *** > after a suspend? I'm no expert on the ISA DMA controller so I could use > some help here. The DMA controller has some bits of state which are potentially in need of restoration as well as a need to ensure you don't suspend while it is running I would imagine. Even for bus masters I believe you would need to restore the DMA enable bits. See include/asm-i386/dma.h but note that some registers have side effects and the dma_outb etc are used to get required delays on some PCs Alan ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-05-28 13:51 ` Alan Cox @ 2005-06-05 8:21 ` Pierre Ossman 2005-06-05 14:03 ` Pierre Ossman 0 siblings, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-06-05 8:21 UTC (permalink / raw) To: Alan Cox; +Cc: LKML Alan Cox wrote: > >The DMA controller has some bits of state which are potentially in need >of restoration as well as a need to ensure you don't suspend while it is >running I would imagine. Even for bus masters I believe you would need >to restore the DMA enable bits. > > I avoid using DMA during suspend to make sure it doesn't get into some wierd state, but that doesn't solve the problem. I added some debug output to the driver, dumping the DMA controller's registers before and after suspend and it seems it goes completely apeshit. The registers are filled with, what it seems, random data. The reason it stops working seems to be that channel 4 gets disabled killing the cascaded channels. I'm going to try and confirm this today. Now for the solution. Reseting the DMA controller from a device driver isn't really a good solution. I had a look in dma.c but it didn't seem to have any place to attach resume/suspend functions. Also, I couldn't find where DMA channel 4 is enabled during startup. Or does the kernel count on BIOS doing this? Rgds Pierre ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-05 8:21 ` Pierre Ossman @ 2005-06-05 14:03 ` Pierre Ossman 2005-06-16 15:53 ` Pierre Ossman 0 siblings, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-06-05 14:03 UTC (permalink / raw) To: Alan Cox; +Cc: LKML Pierre Ossman wrote: > > I added some debug output to the driver, dumping the DMA controller's > registers before and after suspend and it seems it goes completely > apeshit. The registers are filled with, what it seems, random data. The > reason it stops working seems to be that channel 4 gets disabled killing > the cascaded channels. I'm going to try and confirm this today. > Confirmed. By explicitly reenabling DMA channel 4 in the driver on resumt the DMA transfers work fine. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-05 14:03 ` Pierre Ossman @ 2005-06-16 15:53 ` Pierre Ossman 2005-06-16 16:06 ` Russell King 0 siblings, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-06-16 15:53 UTC (permalink / raw) To: LKML; +Cc: Alan Cox So how do we solve this problem? We should do a master clear and then enable channel 4 after a suspend. The question is where. I see three possible places: * In the suspend code in kernel/power. * In the driver actually handling the suspend (ACPI/APM/etc.). * Via the device layer by adding a device for the DMA controller. Which would be the preferred solution? Rgds Pierre ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-16 15:53 ` Pierre Ossman @ 2005-06-16 16:06 ` Russell King 2005-06-18 8:15 ` Pierre Ossman 2005-06-30 8:00 ` Pierre Ossman 0 siblings, 2 replies; 13+ messages in thread From: Russell King @ 2005-06-16 16:06 UTC (permalink / raw) To: Pierre Ossman; +Cc: LKML, Alan Cox On Thu, Jun 16, 2005 at 05:53:47PM +0200, Pierre Ossman wrote: > So how do we solve this problem? We should do a master clear and then > enable channel 4 after a suspend. The question is where. I see three > possible places: > > * In the suspend code in kernel/power. > * In the driver actually handling the suspend (ACPI/APM/etc.). > * Via the device layer by adding a device for the DMA controller. > > Which would be the preferred solution? Shouldn't there be a system device for the DMA controller? I think that should have appropriate hooks into the power management system to do the necessary magic to restore whatever's needed - just like we do for the PIC. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-16 16:06 ` Russell King @ 2005-06-18 8:15 ` Pierre Ossman 2005-06-19 15:45 ` Russell King 2005-06-30 8:00 ` Pierre Ossman 1 sibling, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-06-18 8:15 UTC (permalink / raw) To: Russell King; +Cc: LKML, Alan Cox Russell King wrote: > >Shouldn't there be a system device for the DMA controller? I think >that should have appropriate hooks into the power management system >to do the necessary magic to restore whatever's needed - just like >we do for the PIC. > > > I'll have a look at how the PIC is handled then. Any corner cases I should be aware of? Rgds Pierre ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-18 8:15 ` Pierre Ossman @ 2005-06-19 15:45 ` Russell King 0 siblings, 0 replies; 13+ messages in thread From: Russell King @ 2005-06-19 15:45 UTC (permalink / raw) To: Pierre Ossman; +Cc: LKML, Alan Cox On Sat, Jun 18, 2005 at 10:15:44AM +0200, Pierre Ossman wrote: > Russell King wrote: > >Shouldn't there be a system device for the DMA controller? I think > >that should have appropriate hooks into the power management system > >to do the necessary magic to restore whatever's needed - just like > >we do for the PIC. > > I'll have a look at how the PIC is handled then. Any corner cases I > should be aware of? No idea on that score I'm afraid. Alan may know better. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-16 16:06 ` Russell King 2005-06-18 8:15 ` Pierre Ossman @ 2005-06-30 8:00 ` Pierre Ossman 2005-06-30 11:28 ` Alan Cox 1 sibling, 1 reply; 13+ messages in thread From: Pierre Ossman @ 2005-06-30 8:00 UTC (permalink / raw) To: LKML; +Cc: Russell King, Alan Cox, Linus Torvalds [-- Attachment #1: Type: text/plain, Size: 374 bytes --] 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 [-- Attachment #2: i8237-i386.patch --] [-- Type: text/x-patch, Size: 2134 bytes --] 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/ ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-30 8:00 ` Pierre Ossman @ 2005-06-30 11:28 ` Alan Cox 2005-06-30 12:20 ` Pierre Ossman 0 siblings, 1 reply; 13+ messages in thread From: Alan Cox @ 2005-06-30 11:28 UTC (permalink / raw) To: Pierre Ossman; +Cc: LKML, Russell King, Linus Torvalds On Iau, 2005-06-30 at 09:00, Pierre Ossman wrote: > + 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); It is spelt "weird" Looks basically OK although it would be good to document the situation for a bus mastering DMA controller. Does the device have to reconfigure the DMA on a resume or is that something the restore code for the device should handle ? My own feeling is tha we should dump that on the device (safer) and also expect the device to prevent suspends during an active DMA transfer (eg floppy) Alan ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: ISA DMA controller hangs 2005-06-30 11:28 ` Alan Cox @ 2005-06-30 12:20 ` Pierre Ossman 2005-06-30 17:55 ` [PATCH 1/2] ISA DMA suspend for i386 Pierre Ossman 2005-06-30 17:58 ` [PATCH 2/2] ISA DMA suspend for x86_64 Pierre Ossman 0 siblings, 2 replies; 13+ messages in thread From: Pierre Ossman @ 2005-06-30 12:20 UTC (permalink / raw) To: Alan Cox; +Cc: LKML, Russell King, Linus Torvalds Alan Cox wrote: > >It is spelt "weird" > > Ooops... :) >Looks basically OK although it would be good to document the situation >for a bus mastering DMA controller. Does the device have to reconfigure >the DMA on a resume or is that something the restore code for the device >should handle ? > >My own feeling is tha we should dump that on the device (safer) and also >expect the device to prevent suspends during an active DMA transfer (eg >floppy) > > > If you mean that the device drivers should restore any state then I fully agree. A central restore of the complete state of the DMA controller would require keeping a copy of all data passed to it (since some registers are write only). The reason for my piece of code here is that nobody "owns" channel 4 so it must be restored centrally. Also, resetting the other registers makes the DMA controller behave the same way on all systems (from the drivers' point of view at least). Preventing suspend also needs to be done from the drivers. Simply because only they can determine when the devices are doing the transfer (examining the DMA controller will only tell us if it's _prepared_ for a transfer). I'll fix the typo and whip up a patch for x86_64 then. Rgds Pierre ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 1/2] ISA DMA suspend for i386 2005-06-30 12:20 ` Pierre Ossman @ 2005-06-30 17:55 ` Pierre Ossman 2005-06-30 17:58 ` [PATCH 2/2] ISA DMA suspend for x86_64 Pierre Ossman 1 sibling, 0 replies; 13+ messages in thread From: Pierre Ossman @ 2005-06-30 17:55 UTC (permalink / raw) To: Linus Torvalds; +Cc: Alan Cox, LKML, Russell King [-- Attachment #1: Type: text/plain, Size: 177 bytes --] 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> [-- Attachment #2: i8237-i386.patch --] [-- Type: text/x-patch, Size: 2126 bytes --] 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 weird 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/ ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH 2/2] ISA DMA suspend for x86_64 2005-06-30 12:20 ` Pierre Ossman 2005-06-30 17:55 ` [PATCH 1/2] ISA DMA suspend for i386 Pierre Ossman @ 2005-06-30 17:58 ` Pierre Ossman 1 sibling, 0 replies; 13+ messages in thread From: Pierre Ossman @ 2005-06-30 17:58 UTC (permalink / raw) To: Linus Torvalds; +Cc: Alan Cox, LKML, Russell King [-- Attachment #1: Type: text/plain, Size: 301 bytes --] 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> Word of warning, I haven't tested this platform since I don't have any x86_64 hardware. But it shouldn't differ from i386. [-- Attachment #2: i8237-x86_64.patch --] [-- Type: text/x-patch, Size: 2213 bytes --] Index: linux-wbsd/arch/x86_64/kernel/i8237.c =================================================================== --- linux-wbsd/arch/x86_64/kernel/i8237.c (revision 0) +++ linux-wbsd/arch/x86_64/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 weird 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/x86_64/kernel/Makefile =================================================================== --- linux-wbsd/arch/x86_64/kernel/Makefile (revision 153) +++ linux-wbsd/arch/x86_64/kernel/Makefile (working copy) @@ -7,7 +7,7 @@ obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o \ ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_x86_64.o \ x8664_ksyms.o i387.o syscall.o vsyscall.o \ - setup64.o bootflag.o e820.o reboot.o quirks.o + setup64.o bootflag.o e820.o reboot.o quirks.o i8237.o obj-$(CONFIG_X86_MCE) += mce.o obj-$(CONFIG_X86_MCE_INTEL) += mce_intel.o ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2005-06-30 18:09 UTC | newest] Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2005-05-28 13:38 ISA DMA controller hangs Pierre Ossman 2005-05-28 13:51 ` Alan Cox 2005-06-05 8:21 ` Pierre Ossman 2005-06-05 14:03 ` Pierre Ossman 2005-06-16 15:53 ` Pierre Ossman 2005-06-16 16:06 ` Russell King 2005-06-18 8:15 ` Pierre Ossman 2005-06-19 15:45 ` Russell King 2005-06-30 8:00 ` Pierre Ossman 2005-06-30 11:28 ` Alan Cox 2005-06-30 12:20 ` Pierre Ossman 2005-06-30 17:55 ` [PATCH 1/2] ISA DMA suspend for i386 Pierre Ossman 2005-06-30 17:58 ` [PATCH 2/2] ISA DMA suspend for x86_64 Pierre Ossman
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