Re: [PATCH] net: tulip: Set PCI revision to match dec21143

[Philippe Mathieu-Daudé]

On 6/10/20 11:13 PM, Sven Schnelle wrote:
> On Mon, Jun 08, 2020 at 12:17:11AM +0200, Philippe Mathieu-Daudé wrote:
>> Hi Sven, could you review thiw one-line patch?
>>
>> On 4/18/20 2:25 AM, Marek Vasut wrote:
>>> The tulip driver claims to emulate dec21143 and it does not emulate 
>>> dec21142.
>>> The dec21142 and dec21143 can be discerned by the PCI revision register,
>>> where dec21142 reports value < 0x20 and dec21143 value >= 0x20. E.g. the
>>> U-Boot 'tulip' driver also only supports dec21143 and verifies that the
>>> PCI revision ID is >= 0x20, otherwise refuses to operate such a card.
>>>
>>> This patch sets the PCI revision ID to 0x20 to match the dec21143 and
>>> thus also permits e.g. U-Boot to work with the tulip emulation.
>>>
>>> Fixes: 34ea023d4b95 ("net: add tulip (dec21143) driver")
>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
>>> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Cc: Peter Maydell <peter.maydell@linaro.org>
>>> Cc: Prasad J Pandit <pjp@fedoraproject.org>
>>> Cc: Sven Schnelle <svens@stackframe.org>
>>> ---
>>>  hw/net/tulip.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/hw/net/tulip.c b/hw/net/tulip.c
>>> index 1295f51d07..ffb6c2479a 100644
>>> --- a/hw/net/tulip.c
>>> +++ b/hw/net/tulip.c
>>> @@ -962,6 +962,8 @@ static void pci_tulip_realize(PCIDevice *pci_dev, Error 
>>> **errp)
>>>  
>>>      pci_conf = s->dev.config;
>>>      pci_conf[PCI_INTERRUPT_PIN] = 1; /* interrupt pin A */
>>> +    /* Anything with revision < 0x20 is DC21142, anything >= 0x20 is 
>>> DC21143 */
>>> +    pci_conf[PCI_REVISION_ID] = 0x20;
>>>  
>>>      s->eeprom = eeprom93xx_new(&pci_dev->qdev, 64);
>>>      tulip_fill_eeprom(s);
>>>
>>
> 
> The intel datasheet for the DEC21143 lists only Rev IDs > 30 for this 
> particular family:
> 
> 21143-PB,TB,PC,TC - 0x30
> 21143-PD,TD - x041
> 
> but maybe older DEC chips used 0x20 - don't know. The most interesting 
> question is
> whether ancient OS' like HP-UX or Windows XP would still work with this 
> patch, but
> i don't have test images at hand right now.

So the question is whether your HP-UX/WinXP images also boot with a
DEC21142 (you aimed to model a DEC21143, and it is tested anyway).

Marek, suggestion:

Make pci_tulip_realize() abstract, add dec21142 and dec21143 models as
you suggested, making 'tulip' an alias of dec21142 for backward
compatibility. You can then use the dec21143.