Re: [PATCH v5 -next 07/11] PCI: brcmstb: Adjust PHY PLL setup to use a 54MHz input refclk

Hi Bjorn,

On 2/21/25 11:33 PM, Bjorn Helgaas wrote:

On Mon, Jan 20, 2025 at 03:01:15PM +0200, Stanimir Varbanov wrote:

quoted

The default input reference clock for the PHY PLL is 100Mhz, except for
some devices where it is 54Mhz like bcm2712C1 and bcm2712D0.

To implement this adjustments introduce a new .post_setup op in
pcie_cfg_data and call it at the end of brcm_pcie_setup function.

The bcm2712 .post_setup callback implements the required MDIO writes that
switch the PLL refclk and also change PHY PM clock period.

Without this RPi5 PCIex1 is unable to enumerate endpoint devices on
the expansion connector.

This makes it sound like this patch should be reordered before "[PATCH
v5 -next 06/11] PCI: brcmstb: Add bcm2712 support".

We don't really want a driver to claim a bcm2712 controller before
it's able to enumerate devices, because that would break bisection
through this.

I absolutely agree with you in regards to bisect-ability. But to satisfy
this I have to squash "Adjust PHY PLL ..." into "PCI: brcmstb: Add
bcm2712 support" to avoid a warning about not used function. If that
works I'll send a new rebased controller/brcmstb version (v6).

~Stan