Subject: Re: pci overmapping

From: Scott Wood <[email-masked]>
Date: Thu, 2 May 2013 12:13:59 -0500

On 05/02/2013 12:05:42 PM, Yoder Stuart-B08248 wrote:
> Kumar,
>=20
> In fsl_pci.c there is a change you made a while back:
>   "powerpc/fsl: Setup PCI inbound window based on actual amount of =20
> memory"
>=20
> ...and there is this comment in the code:
>=20
>     /* PCIe can overmap inbound & outbound since RX & TX are =20
> separated */
>     if (early_find_capability(hose, 0, 0, PCI_CAP_ID_EXP)) {
>=20
> You are implying that PCIe can overmap and PCI can't.  Why is
> that?   (I'm assuming that 'overmap' means that inbound window
> can extend beyond the end of ram.)

Shouldn't the concern be whether we're overlapping outbound, not merely =20
whether we go beyond the end of RAM?

And couldn't inbound/outbound overlap be an issue even on PCIe, if =20
there's a PCI bridge underneath it?

-Scott=