Re: [PATCH v5 00/18] power: sequencing: implement the subsystem and add first users

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On 19/02/2024 13:33, Dmitry Baryshkov wrote:
On Mon, 19 Feb 2024 at 14:23, Bartosz Golaszewski <brgl@xxxxxxxx> wrote:

On Mon, Feb 19, 2024 at 11:26 AM Dmitry Baryshkov
<dmitry.baryshkov@xxxxxxxxxx> wrote:


For WCN7850 we hide the existence of the PMU as modeling it is simply not
necessary. The BT and WLAN devices on the device-tree are represented as
consuming the inputs (relevant to the functionality of each) of the PMU

We are describing the hardware. From the hardware point of view, there
is a PMU. I think at some point we would really like to describe all
Qualcomm/Atheros WiFI+BT units using this PMU approach, including the
older ath10k units present on RB3 (WCN3990) and db820c (QCA6174).

While I agree with older WiFi+BT units, I don't think it's needed for
WCN7850 since BT+WiFi are now designed to be fully independent and PMU is

I don't see any significant difference between WCN6750/WCN6855 and
WCN7850 from the PMU / power up point of view. Could you please point
me to the difference?

The WCN7850 datasheet clearly states there's not contraint on the WLAN_EN
and BT_EN ordering and the only requirement is to have all input regulators
up before pulling up WLAN_EN and/or BT_EN.

This makes the PMU transparent and BT and WLAN can be described as independent.

 From the hardware perspective, there is a PMU. It has several LDOs. So
the device tree should have the same style as the previous

My thinking was this: yes, there is a PMU but describing it has no
benefit (unlike QCA6x90). If we do describe, then we'll end up having
to use pwrseq here despite it not being needed because now we won't be
able to just get regulators from WLAN/BT drivers directly.

So I also vote for keeping it this way. Let's go into the package
detail only if it's required.

The WiFi / BT parts are not powered up by the board regulators. They
are powered up by the PSU. So we are not describing it in the accurate

I disagree, the WCN7850 can also be used as a discrete PCIe M.2 card, and in
this situation the PCIe part is powered with the M.2 slot and the BT side
is powered separately as we currently do it now.

So yes there's a PMU, but it's not an always visible hardware part, from the
SoC PoV, only the separate PCIe and BT subsystems are visible/controllable/powerable.


Moreover, I think we definitely want to move BT driver to use only the
pwrseq power up method. Doing it in the other way results in the code
duplication and possible issues because of the regulator / pwrseq
taking different code paths.

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