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

[Sven Schnelle <svens@stackframe.org>]

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.

Regards
Sven