Re: [PATCH] PCI: qcom: add missing supplies required for msm8996

On 23/01/18 10:14, Stanimir Varbanov wrote:

Hi,

On 01/23/2018 11:46 AM, Srinivas Kandagatla wrote:

quoted

On 23/01/18 09:23, Stanimir Varbanov wrote:

quoted

Hey Srini,

As there are no comments I'd propose to change the endpoint supplies to
more generic names.

Sure, I will respin this with your suggestions, except the 3v3 and 1v5
suffix due to the reasons below:

quoted

quoted

+- vdda-1p8-supply:
+    Usage: required for msm8996
+    Value type: <phandle>
+    Definition: A phandle to the 1.8v analog power supply
+

This should be dropped, because it is part of the phy.

Yep.

quoted

quoted

   - vdda_phy-supply:
       Usage: required for ipq/apq8064
       Value type: <phandle>

@@ -189,6 +194,15 @@
       Value type: <phandle>
       Definition: A phandle to the analog power supply for IC which

generates
               reference clock
+- vddpe-supply:
+    Usage: optional
+    Value type: <phandle>
+    Definition: A phandle to the PCIe endpoint power supply

vddpe_3v3-supply

Why do we need suffix here? AFAIU, It does not add any value, instead it
would confuse the users.

vddpe and vddpe1 is already confusing as well.

I partly agree with you.

How would you represent if there are two power 3v3 supplies for the 
endpoint?

Lets imagine that powering up the endpointX needs some specific sequence
between 3v3 and 1v5 and endpointY (which could be connected on the same
PCIe lane) has different power sequence, how we would handle that in the
qcom pcie host driver?

power sequencing is all together a different issue, that is not 
addressed in this patch. Am hoping that this will be fixed as part of 
making pwrseq interface more generic. Not sure where it endedup now!!

--srini

quoted

These are power supplies for endpoint which could be of any voltage. In

I don't think that could be any values see PCIe mini card
electromechanical specification. There on the connector are provided 3v3
and 1v5.

quoted

this case both endpoint supplies are 3v3, these could be 1.8 or 5v or
12v in some other cases.

If we see hw designs with 5v and 12v we could extend the binding and the
driver with support for them. I want to be exact in the names and
voltages in the driver and bindings.