[PATCH] libata:pata_atiixp: Don't use unconnected secondary port on SB600

[PATCH] libata:pata_atiixp: Don't use unconnected secondary port on SB600

[Darren Stevens]

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  AmigaOS...........: http://yam.ch/
  Unix/MacOS/Windows: http://www.mozilla.com/thunderbird/

General information about MIME can be found at:
http://en.wikipedia.org/wiki/MIME

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    The AMD SB600 southbridge has an PATA IDE interface, but the
    secondary port has no physical connections, so is disabled in
    the PCI header which makes it appear as a legacy port.
    
    On most systems this causes no trouble, but the Amigaone X1000 has
    an SB600 connected to a PowerPC SoC PCI-e root port, with an
    emulated ISA bus. On this system a kernel panic occurs at boot
    time during device attach for the secondary port.
    
    Mark the port as 'dummy' to prevent this. As a bonus, disabling
    this will slightly speed up booting on PC systems using an
    SB600 as they will now skip 2 known empty ports.
    
    Signed-off-by: Darren Stevens <Darren@stevens-zone.net>

---

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diff --git a/drivers/ata/pata_atiixp.c b/drivers/ata/pata_atiixp.c
index 49d705c..4d49fd3 100644
--- a/drivers/ata/pata_atiixp.c
+++ b/drivers/ata/pata_atiixp.c
@@ -278,6 +278,10 @@ static int atiixp_init_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	};
 	const struct ata_port_info *ppi[] = { &info, &info };
 
+	/* SB600 doesn't have secondary port wired */
+	if((pdev->device == PCI_DEVICE_ID_ATI_IXP600_IDE))
+		ppi[1] = &ata_dummy_port_info;
+
 	return ata_pci_bmdma_init_one(pdev, ppi, &atiixp_sht, NULL,
 				      ATA_HOST_PARALLEL_SCAN);
 }

Re: [PATCH] libata:pata_atiixp: Don't use unconnected secondary port on SB600

[Tejun Heo]

Hello, Darren.

On Sun, Dec 31, 2017 at 09:11:05PM +0000, Darren Stevens wrote:
>     The AMD SB600 southbridge has an PATA IDE interface, but the
>     secondary port has no physical connections, so is disabled in
>     the PCI header which makes it appear as a legacy port.

How sure are you about the secondary port never being used?  Given the
age of the device and that this has been like this the whole time, I'd
prefer if the workaround were more specific - ie. mark it dummy only
on the specific machines that are known to be broken.  That said, if
we know with certainty that the secondary port is never used, sure.

Thanks.

-- 
tejun

Re: libata:pata_atiixp: Don't use unconnected secondary port on SB600

[Darren Stevens]

Hello Tejun

On 02/01/2018, Tejun Heo wrote:
> Hello, Darren.
>
> On Sun, Dec 31, 2017 at 09:11:05PM +0000, Darren Stevens wrote:
>>     The AMD SB600 southbridge has an PATA IDE interface, but the
>>     secondary port has no physical connections, so is disabled in
>>     the PCI header which makes it appear as a legacy port.
>
> How sure are you about the secondary port never being used?  Given the
> age of the device and that this has been like this the whole time, I'd
> prefer if the workaround were more specific - ie. mark it dummy only
> on the specific machines that are known to be broken.  That said, if
> we know with certainty that the secondary port is never used, sure.

I'm reasonably sure.
>From '46157-sb600-bdg-pub-3.00'

Page 27 section 6.1.2

Note: Secondary IDE channel should always be disabled for there is no pin out for secondary IDE.

However I was trying to keep patches for the X1000 inside arch/powerpc rather than all over the linux tree. If you are OK with a specific patch I can resubmit.

Thanks
Darren

Re: [PATCH] libata:pata_atiixp: Don't use unconnected secondary port on SB600

[Tejun Heo]

On Sun, Dec 31, 2017 at 09:11:05PM +0000, Darren Stevens wrote:
>     The AMD SB600 southbridge has an PATA IDE interface, but the
>     secondary port has no physical connections, so is disabled in
>     the PCI header which makes it appear as a legacy port.
>     
>     On most systems this causes no trouble, but the Amigaone X1000 has
>     an SB600 connected to a PowerPC SoC PCI-e root port, with an
>     emulated ISA bus. On this system a kernel panic occurs at boot
>     time during device attach for the secondary port.
>     
>     Mark the port as 'dummy' to prevent this. As a bonus, disabling
>     this will slightly speed up booting on PC systems using an
>     SB600 as they will now skip 2 known empty ports.
>     
>     Signed-off-by: Darren Stevens <Darren@stevens-zone.net>

Applied to libata/for-4.16.

Thanks.

-- 
tejun