linux-kernel - Re: [PATCH 3/9] PCI: Disable cardbus bridge MEM1 pref CTL

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Message-ID: <CAE9FiQXeNGP3zj2PhWK_Gcnwr9Qsn6LZ74TL2OA2RrztLaewvg@mail.gmail.com>
Date:	Fri, 10 Feb 2012 12:54:41 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Ram Pai <linuxram@...ibm.com>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] PCI: Disable cardbus bridge MEM1 pref CTL

On Fri, Feb 10, 2012 at 12:46 PM, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> On Sat,  4 Feb 2012 22:55:02 -0800
> Yinghai Lu <yinghai@...nel.org> wrote:
>
>> Some BIOS enable both pref for MEM0 and MEM1.
>>
>> but we assume MEM1 is non-pref...
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---
>>  drivers/pci/setup-bus.c |    8 ++++++++
>>  1 files changed, 8 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
>> index 090217a..d5897c3 100644
>> --- a/drivers/pci/setup-bus.c
>> +++ b/drivers/pci/setup-bus.c
>> @@ -914,6 +914,14 @@ static void pci_bus_size_cardbus(struct pci_bus *bus,
>>       if (realloc_head)
>>               add_to_list(realloc_head, bridge, b_res+1, pci_cardbus_io_size, 0 /* dont care */);
>>
>> +     /* MEM1 must not be pref mmio */
>> +     pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
>> +     if (ctrl & PCI_CB_BRIDGE_CTL_PREFETCH_MEM1) {
>> +             ctrl &= ~PCI_CB_BRIDGE_CTL_PREFETCH_MEM1;
>> +             pci_write_config_word(bridge, PCI_CB_BRIDGE_CONTROL, ctrl);
>> +             pci_read_config_word(bridge, PCI_CB_BRIDGE_CONTROL, &ctrl);
>> +     }
>> +
>>       /*
>>        * Check whether prefetchable memory is supported
>>        * by this bridge.
>
> Does this actually fix any bugs?

at least, one of laptop have this problem.

> Dominik, have you tested it?

he tested my for-pci3 and for-pci-busn-alloc branches, both branches
have this patch.

and it does not cause problem to him.

Yinghai
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