Re: [PATCH 2/2] PCI: qcom: Add basic interconnect support

Brian Masney
2022-10-19T14:46:55Z

On Mon, Oct 17, 2022 at 01:24:49PM +0200, Johan Hovold wrote:
> + /*
> + * Some Qualcomm platforms require interconnect bandwidth constraints
> + * to be set before enabling interconnect clocks.
> + *
> + * Set an initial peak bandwidth corresponding to single-lane Gen 1
> + * for the pcie-mem path.
> + */
> + ret = icc_set_bw(pcie->icc_mem, 0, MBps_to_icc(250));

[snip]

> + speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
> + width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
> +
> + switch (speed) {
> + case 1:
> + bw = MBps_to_icc(250);
> + break;
> + case 2:
> + bw = MBps_to_icc(500);
> + break;
> + default:
> + case 3:
> + bw = MBps_to_icc(985);
> + break;
> + }

Just curious: These platforms have a 4 lane PCIe bus. Why use 985
instead of 1000 for the maximum?

Brian