Re: [PATCH v2 2/2] PCI: xilinx-nwl: Enable the clock through CCF

Hi Krzysztof,

On 6/23/21 3:53 PM, Krzysztof Wilczyński wrote:

[+cc Sasha for visibility]

Hi Michal,

Thank you for sending v2 so promptly!  And for all the extra changes and
fixes.  Much appreciated!

quoted

Enable PCIE reference clock. There is no remove function that's why
this should be enough for simple operation.
Normally this clock is enabled by default by firmware but there are
usecases where this clock should be enabled by driver itself.
It is also good that clock user is recorded in clock framework.

Small nitpicks: it would be PCIe here in the above and in the error
message (this is as per [1]), and "use cases" also in the above. 

This can be corrected when the patch will be merged by either Bjorn or
Lorenzo, to avoid sending v3 unnecessarily, provided that they would
have a moment to do it, of course.

Ok. Will wait for them.

quoted

Fixes: ab597d35ef11 ("PCI: xilinx-nwl: Add support for Xilinx NWL PCIe Host Controller")

Thank you!

Does it make sense for this change to be back-ported to stable and
long-term kernels?

I am asking to make sure we do the right thing here, as I can imagine
that older kernels (primarily because some folks could use, for example,
Ubuntu LTS releases for development) might often be used by people who
work with the Xilinx FPGAs and such.

I think that make sense to do so. I haven't had a time to take look at
it closely but I think on Xilinx ZynqMP zcu102 board this missing patch
is causing hang when standard debian 5.10 is used.

[...]

quoted

+	err = clk_prepare_enable(pcie->clk);
+	if (err) {
+		dev_err(dev, "can't enable pcie ref clock\n");
+		return err;
+	}
+

As per the nitpick above, it would be "PCIe", but probably no need to
send v3 to correct this.

I will keep my eyes on it and will update it if v3 is required.

Thanks,
Michal

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel