From: Rob Herring <email@example.com>
To: Bjorn Andersson <firstname.lastname@example.org>
Cc: Dmitry Baryshkov <email@example.com>,
Bjorn Helgaas <firstname.lastname@example.org>,
Andy Gross <email@example.com>, Arnd Bergmann <firstname.lastname@example.org>,
Greg Kroah-Hartman <email@example.com>,
Stanimir Varbanov <firstname.lastname@example.org>,
Lorenzo Pieralisi <email@example.com>,
Bjorn Helgaas <firstname.lastname@example.org>,
Manivannan Sadhasivam <email@example.com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
Subject: Re: [PATCH v2 3/5] pcie-qcom: provide a way to power up qca6390 chip on RB5 platform
Date: Tue, 2 Feb 2021 15:37:25 -0600 [thread overview]
Message-ID: <CAL_JsqJoKEVUs0f7rP87M3Wh6yVvB-bYi7vBprti8hoim3-e-A@mail.gmail.com> (raw)
On Tue, Feb 2, 2021 at 1:48 PM Bjorn Andersson
> On Sat 30 Jan 10:14 CST 2021, Dmitry Baryshkov wrote:
> > On Sat, 30 Jan 2021 at 06:53, Bjorn Andersson
> > <firstname.lastname@example.org> wrote:
> > >
> > > On Fri 29 Jan 16:19 CST 2021, Dmitry Baryshkov wrote:
> > >
> > > > On Sat, 30 Jan 2021 at 00:50, Bjorn Helgaas <email@example.com> wrote:
> > > > >
> > > > > On Fri, Jan 29, 2021 at 06:45:21AM +0300, Dmitry Baryshkov wrote:
> > > > > > On 28/01/2021 22:26, Rob Herring wrote:
> > > > > > > On Thu, Jan 28, 2021 at 11:52 AM Dmitry Baryshkov
> > > > > > > <firstname.lastname@example.org> wrote:
> > > > > > > >
> > > > > > > > Some Qualcomm platforms require to power up an external device before
> > > > > > > > probing the PCI bus. E.g. on RB5 platform the QCA6390 WiFi/BT chip needs
> > > > > > > > to be powered up before PCIe0 bus is probed. Add a quirk to the
> > > > > > > > respective PCIe root bridge to attach to the power domain if one is
> > > > > > > > required, so that the QCA chip is started before scanning the PCIe bus.
> > > > > > >
> > > > > > > This is solving a generic problem in a specific driver. It needs to be
> > > > > > > solved for any PCI host and any device.
> > > > > >
> > > > > > Ack. I see your point here.
> > > > > >
> > > > > > As this would require porting code from powerpc/spark of-pci code and
> > > > > > changing pcie port driver to apply power supply before bus probing happens,
> > > > > > I'd also ask for the comments from PCI maintainers. Will that solution be
> > > > > > acceptable to you?
> > > > >
> > > > > I can't say without seeing the code. I don't know enough about this
> > > > > scenario to envision how it might look.
> > > > >
> > > > > I guess the QCA6390 is a PCIe device? Why does it need to be powered
> > > > > up before probing? Shouldn't we get a link-up interrupt when it is
> > > > > powered up so we could probe it then?
> > > >
> > > > Not quite. QCA6390 is a multifunction device, with PCIe and serial
> > > > parts. It has internal power regulators which once enabled will
> > > > powerup the PCIe, serial and radio parts. There is no need to manage
> > > > regulators. Once enabled they will automatically handle device
> > > > suspend/resume, etc.
> > > >
> > >
> > > So what you're saying is that if either the PCI controller or bluetooth
> > > driver probes these regulators will be turned on, indefinitely?
> > >
> > > If so, why do we need a driver to turn them on, rather than just mark
> > > them as always-on?
> > >
> > > What's the timing requirement wrt regulators vs WL_EN/BT_EN?
> > According to the documentation I have, they must be enabled right
> > after enabling powering the chip and they must stay enabled all the
> > time.
> So presumably just marking these things always-on and flipping the GPIO
> statically won't be good enough due to the lack of control over the
> This really do look like a simplified case of what we see with the
> PCIe attached modems, where similar requirements are provided, but also
> the ability to perform a device specific reset sequence in case the
> hardware has locked up. I'm slightly worried about the ability of
> extending your power-domain model to handle the restart operation
I think this is an abuse of 'power-domains'. Just define the
regulators in both WiFi and BT nodes and have each driver enable them.
They're refcounted. If that's still not enough control over the power
sequencing, then create a 3rd entity to do it, but that doesn't need
to leak into DT. You already have all the information you need.
next prev parent reply other threads:[~2021-02-02 21:38 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 17:52 [PATCH v2 0/5] Add support for Qualcomm QCA639x chips family Dmitry Baryshkov
2021-01-28 17:52 ` [PATCH v2 1/5] misc: qca639x: add support for QCA639x powerup sequence Dmitry Baryshkov
2021-01-31 14:18 ` Kalle Valo
2021-01-28 17:52 ` [PATCH v2 2/5] arm64: qcom: dts: qrb5165-rb5: add qca6391 power device Dmitry Baryshkov
2021-01-30 3:47 ` Bjorn Andersson
2021-01-30 3:59 ` Manivannan Sadhasivam
2021-01-28 17:52 ` [PATCH v2 3/5] pcie-qcom: provide a way to power up qca6390 chip on RB5 platform Dmitry Baryshkov
[not found] ` <CAL_JsqLRn40h0K-Fze5m1LS2+raLp94LariMkUh7XtekTBT5+Q@mail.gmail.com>
2021-01-29 3:45 ` Dmitry Baryshkov
2021-01-29 21:50 ` Bjorn Helgaas
2021-01-29 22:19 ` Dmitry Baryshkov
2021-01-29 22:39 ` Bjorn Helgaas
2021-01-30 3:53 ` Bjorn Andersson
2021-01-30 16:14 ` Dmitry Baryshkov
2021-02-02 19:48 ` Bjorn Andersson
2021-02-02 21:37 ` Rob Herring [this message]
2021-02-02 21:50 ` Bjorn Andersson
2021-02-03 4:14 ` Dmitry Baryshkov
2021-01-29 23:39 ` Rob Herring
2021-06-13 18:40 ` Konrad Dybcio
2021-01-28 17:52 ` [PATCH v2 4/5] arm64: dtb: qcom: qrb5165-rb5: add bridge@0,0 to power up qca6391 chip Dmitry Baryshkov
[not found] ` <CAL_Jsq+uim_0fDsCqSjgbz-xzUEu4GAf+KOgxSd1KdrFWjhd3Q@mail.gmail.com>
2021-01-29 3:48 ` Dmitry Baryshkov
2021-01-28 17:52 ` [PATCH v2 5/5] arm64: dts: qcom: Add Bluetooth support on RB5 Dmitry Baryshkov
[not found] ` <CAL_Jsq+nNRv3KceHthgktHR1oRMs+eKWC4O7n0k78izs1aTPfA@mail.gmail.com>
2021-01-29 3:49 ` Dmitry Baryshkov
2021-02-02 6:16 ` Manivannan Sadhasivam
2021-01-30 8:04 [PATCH v2 3/5] pcie-qcom: provide a way to power up qca6390 chip on RB5 platform Yassine Oudjana
2021-01-30 16:12 ` Dmitry Baryshkov
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