Date:   Wed, 01 Mar 2023 09:17:50 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        linux-arm-msm@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v1 00/15] create power sequencing subsystem

Hi,

sorry for being late to the party.

Am Mittwoch, 19. Oktober 2022, 08:03:22 CET schrieb Dmitry Baryshkov:
> Ho,
> 
> On Thu, 13 Oct 2022 at 22:50, Matthias Kaehlcke <mka@...omium.org> wrote:
> > Do you still plan to refresh this series?
> > 
> > I know there have been multiple attempts to get something similar
> > landed in the past 10 year or so. Your series didn't seem to get
> > much pushback from maintainers, might be worth sending a refresh :)
> 
> Yes, I hope to return to it eventually. I just had no time for it lately.

I just found this thread while searching for power sequencing devices in 
Linux. From what I understand this is transforming the existing mmc pwrseq 
drivers into generic ones. What is the intention of this new subsystem? What 
is it supposed to address?
In my case I have an LTE module attached via USB, but in order to use it I 
need to perform several steps:
1. apply power supply
2. Issue a reset pulse(!), the length actually defines whether its a reset or 
poweroff/on
3a. wait for a GPIO to toggle
3b. wait a minimum time
4a. device will enumerate on USB
4b. device can be access using UART

This is something required to actually see/detect the device in the first 
place, thus it cannot be part of the device driver side.
Is this something pwrseq is supposed to address?

Best regards,
Alexander

> > On Wed, Oct 06, 2021 at 06:53:52AM +0300, Dmitry Baryshkov wrote:
> > > This is a proposed power sequencer subsystem. This is a
> > > generification of the MMC pwrseq code. The subsystem tries to abstract
> > > the idea of complex power-up/power-down/reset of the devices.
> > > 
> > > The primary set of devices that promted me to create this patchset is
> > > the Qualcomm BT+WiFi family of chips. They reside on serial+platform
> > > or serial + SDIO interfaces (older generations) or on serial+PCIe (newer
> > > generations).  They require a set of external voltage regulators to be
> > > powered on and (some of them) have separate WiFi and Bluetooth enable
> > > GPIOs.
> > > 
> > > The major drawback for now is the lack of proper PCIe integration
> > > At this moment support for PCIe is hacked up to be able to test the
> > > PCIe part of qca6390. Proper PCIe support would require automatically
> > > powering up the devices before the scan basing on the proper device
> > > structure in the device tree. This two last patches are noted as WIP and
> > > are included into the patchset for the purpose of testing WiFi on newer
> > > chips (like qca6390/qca6391).
> > > 
> > > Changes since RFC v2:
> > >  - Add documentation for the pwrseq code. Document data structures,
> > >  
> > >    macros and exported functions.
> > >  
> > >  - Export of_pwrseq_xlate_onecell()
> > >  - Add separate pwrseq_set_drvdata() function to follow the typical API
> > >  
> > >    design
> > >  
> > >  - Remove pwrseq_get_optional()/devm_pwrseq_get_optional()
> > >  - Moved code to handle old mmc-pwrseq binding to the MMC patch
> > >  - Split of_pwrseq_xlate_onecell() support to a separate patch
> > > 
> > > Changes since RFC v1:
> > >  - Provider pwrseq fallback support
> > >  - Implement fallback support in pwrseq_qca.
> > >  - Mmove susclk handling to pwrseq_qca.
> > >  - Significantly simplify hci_qca.c changes, by dropping all legacy
> > >  
> > >    code. Now hci_qca uses only pwrseq calls to power up/down bluetooth
> > >    parts of the chip.
> > > 
> > > _______________________________________________
> > > ath10k mailing list
> > > ath10k@...ts.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/ath10k


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