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SubjectRe: [PATCH] enable readback to get HPET working on ATI SB4x00, kernel 2.6.35_rc5
Am 14.07.2010 23:04, schrieb Thomas Gleixner:
> On Wed, 14 Jul 2010, Borislav Petkov wrote:
>
>
>> From: Linus Torvalds<torvalds@linux-foundation.org>
>> Date: Wed, Jul 14, 2010 at 02:17:27PM -0400
>>
>>
>>>> I'll try to find out which chipsets are actually affected but in the
>>>> meantime we might want to do a temporary fix by enabling the readback
>>>> back(!) on all ATI chipsets so that we don't uncover anymore bugs like
>>>> the one above, hmmm?
>>>>
>>> That sounds like the right solution for now, yes. Rather than make
>>> the readback quirk depend on one particular SMBUS revision, make it
>>> happen unconditionally for an AMD northbridge (or is the HPET in the
>>> SB?
>>>
>> Yeah, its in the southbridge which is part of the chipset. Actually
>> we'll have to somehow match ATI chipsets only since we have also nVidia
>> chipsets with AMD cpus in them.
>>
>> /me goes to meditate a little about it.
>>
>>
>>> I forget - somebody who knows the details and can test it on a
>>> machine or two should do the actual patch).
>>>
>> I'll try to cook up something unless someone beats me to it.
>>
> The patch below works on my collection of ATI chipset based machines.
>
> Stefan, does it solve your problem too ?
>
> Thanks,
>
> tglx
> -----
>
> Subject: x86-ati-chipsets-hpet-force-readback.patch
> From: Thomas Gleixner<tglx@linutronix.de>
> Date: Wed, 14 Jul 2010 21:36:27 +0200
>
> Signed-off-by: Thomas Gleixner<tglx@linutronix.de>
> Index: linux-2.6/arch/x86/kernel/early-quirks.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/early-quirks.c
> +++ linux-2.6/arch/x86/kernel/early-quirks.c
> @@ -18,6 +18,7 @@
> #include<asm/apic.h>
> #include<asm/iommu.h>
> #include<asm/gart.h>
> +#include<asm/hpet.h>
>
> static void __init fix_hypertransport_config(int num, int slot, int func)
> {
> @@ -191,6 +192,21 @@ static void __init ati_bugs_contd(int nu
> }
> #endif
>
> +/*
> + * Force the read back of the CMP register in hpet_next_event()
> + * to work around the problem that the CMP register write seems to be
> + * delayed. See hpet_next_event() for details.
> + *
> + * We do this on all SMBUS incarnations for now until we have more
> + * information about the affected chipsets.
> + */
> +static void __init ati_hpet_bugs(int num, int slot, int func)
> +{
> +#ifdef CONFIG_HPET_TIMER
> + hpet_readback_cmp = 1;
> +#endif
> +}
> +
> #define QFLAG_APPLY_ONCE 0x1
> #define QFLAG_APPLIED 0x2
> #define QFLAG_DONE (QFLAG_APPLY_ONCE|QFLAG_APPLIED)
> @@ -220,6 +236,8 @@ static struct chipset early_qrk[] __init
> PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
> { PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
> PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs_contd },
> + { PCI_VENDOR_ID_ATI, PCI_ANY_ID,
> + PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_hpet_bugs },
> {}
> };
>
> Index: linux-2.6/arch/x86/kernel/quirks.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/quirks.c
> +++ linux-2.6/arch/x86/kernel/quirks.c
> @@ -498,15 +498,10 @@ void force_hpet_resume(void)
> * See erratum #27 (Misinterpreted MSI Requests May Result in
> * Corrupted LPC DMA Data) in AMD Publication #46837,
> * "SB700 Family Product Errata", Rev. 1.0, March 2010.
> - *
> - * Also force the read back of the CMP register in hpet_next_event()
> - * to work around the problem that the CMP register write seems to be
> - * delayed. See hpet_next_event() for details.
> */
> static void force_disable_hpet_msi(struct pci_dev *unused)
> {
> hpet_msi_disable = 1;
> - hpet_readback_cmp = 1;
> }
>
> DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
>

Hi, the patch above solves the problem on my machine.

Thanks,
Stephan


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