Re: [PATCH v4 4/4] PCI: qcom: Enable ECAM feature

Bjorn Helgaas
2025-02-10T22:54:33Z

On Fri, Feb 07, 2025 at 04:58:59AM +0530, Krishna Chaitanya Chundru wrote:
> The ELBI registers falls after the DBI space, PARF_SLV_DBI_ELBI register
> gives us the offset from which ELBI starts. so use this offset and cfg
> win to map these regions instead of doing the ioremap again.

> + /* Set the ECAM base */
> + writel_relaxed(lower_32_bits(pci->dbi_phys_addr), pcie->parf + PARF_ECAM_BASE);
> + writel_relaxed(upper_32_bits(pci->dbi_phys_addr), pcie->parf + PARF_ECAM_BASE_HI);
> +
> + /*
> + * The only device on root bus is the Root Port. Any access other than that
> + * should not go out of the link and should return all F's. Since the iATU
> + * is configured for the buses which starts after root bus, block the transactions
> + * starting from function 1 of the root bus to the end of the root bus (i.e from
> + * dbi_base + 4kb to dbi_base + 1MB) from going outside the link.

99% of this file fits in 80 columns. Wrap comments to do the same.

The text doesn't quite make sense because accesses to devices on the
root bus *never* involve a link. Only Root Ports have links and the
links all lead to buses other than the root bus.