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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Johan Hedberg <johan.hedberg@gmail.com>,
	Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
	Kalle Valo <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Stanimir Varbanov <svarbanov@mm-sol.com>,
	MSM <linux-arm-msm@vger.kernel.org>,
	linux-mmc@vger.kernel.org,
	open list <linux-kernel@vger.kernel.org>,
	"open list:BLUETOOTH SUBSYSTEM" <linux-bluetooth@vger.kernel.org>,
	ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [RFC PATCH 00/15] create power sequencing subsystem
Date: Fri, 20 Aug 2021 16:08:21 +0300	[thread overview]
Message-ID: <CAA8EJpoOxerwmwQozL3gp1nX-+oxLMFUFjVPvRy-MoVfPuvqrw@mail.gmail.com> (raw)
In-Reply-To: <1CA665D1-86F0-45A1-862D-17DAB3ABA974@holtmann.org>

Hi,

On Thu, 19 Aug 2021 at 18:23, Marcel Holtmann <marcel@holtmann.org> wrote:
> > This is an RFC of the 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
> > 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.
> >
> > This patchset being an RFC tries to demonstrate the approach, design and
> > usage of the pwrseq subsystem. Following issues are present in the RFC
> > at this moment but will be fixed later if the overall approach would be
> > viewed as acceptable:
> >
> > - No documentation
> >   While the code tries to be self-documenting proper documentation
> >   would be required.
> >
> > - Minimal device tree bindings changes
> >   There are no proper updates for the DT bindings (thus neither Rob
> >   Herring nor devicetree are included in the To/Cc lists). The dt
> >   schema changes would be a part of v1.
> >
> > - 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.
> >
> > ----------------------------------------------------------------
> > Dmitry Baryshkov (15):
> >      power: add power sequencer subsystem
> >      pwrseq: port MMC's pwrseq drivers to new pwrseq subsystem
> >      mmc: core: switch to new pwrseq subsystem
> >      ath10k: add support for pwrseq sequencing
> >      Bluetooth: hci_qca: merge qca_power into qca_serdev
> >      Bluetooth: hci_qca: merge init paths
> >      Bluetooth: hci_qca: merge qca_power_on with qca_regulators_init
> >      Bluetooth: hci_qca: futher rework of power on/off handling
> >      Bluetooth: hci_qca: add support for pwrseq
>
> any chance you can try to abandon patching hci_qca. The serdev support in hci_uart is rather hacking into old line discipline code and it is not aging well. It is really becoming a mess.

I wanted to stay away from rewriting the BT code. But... New driver
would have a bonus point that I don't have to be compatible with old
bindings. In fact we can even make it the other way around: let the
old driver always use regulators and make the new driver support only
the pwrseq. Then it should be possible to drop the old hci_qca driver
together with dropping the old bindings.

> I would say that the Qualcomm serial devices could use a separate standalone serdev driver. A while I send an RFC for a new serdev driver.
>
> https://www.spinics.net/lists/linux-bluetooth/msg74918.html

Any reason why your driver stayed as an RFC and never made it into the
kernel? Do you plan to revive your old RFCs on H:4 and H:5?

> There I had the idea that simple vendor specifics can be in that driver (like the Broadcom part I added there), but frankly the QCA specifics are a bit too specific and it should be a separate driver. However I think this would be a good starting point.
>
> In general a H:4 based Bluetooth driver is dead simple with the help of h4_recv.h helper we have in the kernel. The complicated part is the power management pieces or any vendor specific low-power protocol they are running on that serial line. And since you are touching this anyway, doing a driver from scratch might be lot simpler and cleaner. It would surely help all the new QCA device showing up in the future.

-- 
With best wishes
Dmitry

  reply	other threads:[~2021-08-20 13:08 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17  0:54 [RFC PATCH 00/15] create power sequencing subsystem Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 01/15] power: add power sequencer subsystem Dmitry Baryshkov
2021-08-19 23:37   ` Bjorn Andersson
2021-08-17  0:54 ` [RFC PATCH 02/15] pwrseq: port MMC's pwrseq drivers to new pwrseq subsystem Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 03/15] mmc: core: switch " Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 04/15] ath10k: add support for pwrseq sequencing Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 05/15] Bluetooth: hci_qca: merge qca_power into qca_serdev Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 06/15] Bluetooth: hci_qca: merge init paths Dmitry Baryshkov
2021-08-17  0:54 ` [RFC PATCH 07/15] Bluetooth: hci_qca: merge qca_power_on with qca_regulators_init Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 08/15] Bluetooth: hci_qca: futher rework of power on/off handling Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 09/15] Bluetooth: hci_qca: add support for pwrseq Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 10/15] pwrseq: add support for QCA BT+WiFi power sequencer Dmitry Baryshkov
2021-08-19 23:18   ` Bjorn Andersson
2021-08-20  8:10     ` Dmitry Baryshkov
2021-08-20 16:35       ` Bjorn Andersson
2021-08-17  0:55 ` [RFC PATCH 11/15] arm64: dts: qcom: sdm845-db845c: switch bt+wifi to qca " Dmitry Baryshkov
2021-08-19 23:40   ` Bjorn Andersson
2021-08-17  0:55 ` [RFC PATCH 12/15] arm64: dts: qcom: qrb5165-rb5: add bluetooth support Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 13/15] arm64: dts: qcom: sdm845-db845c: add second channel support to qca power sequencer Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 14/15] WIP: PCI: qcom: use pwrseq to power up bus devices Dmitry Baryshkov
2021-08-19 23:44   ` Bjorn Andersson
2021-08-20  8:50     ` Dmitry Baryshkov
2021-08-17  0:55 ` [RFC PATCH 15/15] WIP: arm64: dts: qcom: qrb5165-rb5: add bus-pwrseq property to pcie0 Dmitry Baryshkov
2021-08-19 15:23 ` [RFC PATCH 00/15] create power sequencing subsystem Marcel Holtmann
2021-08-20 13:08   ` Dmitry Baryshkov [this message]
2021-08-20 17:02     ` Bjorn Andersson
2021-08-20 18:06       ` Dmitry Baryshkov
2021-08-21  6:50     ` Marcel Holtmann

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