From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51FC7C4320A for ; Thu, 19 Aug 2021 15:23:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B2716056C for ; Thu, 19 Aug 2021 15:23:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238634AbhHSPYW convert rfc822-to-8bit (ORCPT ); Thu, 19 Aug 2021 11:24:22 -0400 Received: from coyote.holtmann.net ([212.227.132.17]:59363 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240159AbhHSPYR (ORCPT ); Thu, 19 Aug 2021 11:24:17 -0400 Received: from smtpclient.apple (p5b3d23f8.dip0.t-ipconnect.de [91.61.35.248]) by mail.holtmann.org (Postfix) with ESMTPSA id 04B76CED17; Thu, 19 Aug 2021 17:23:37 +0200 (CEST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [RFC PATCH 00/15] create power sequencing subsystem From: Marcel Holtmann In-Reply-To: <20210817005507.1507580-1-dmitry.baryshkov@linaro.org> Date: Thu, 19 Aug 2021 17:23:36 +0200 Cc: Andy Gross , Bjorn Andersson , Ulf Hansson , Johan Hedberg , Luiz Augusto von Dentz , Kalle Valo , "David S. Miller" , Jakub Kicinski , Stanimir Varbanov , MSM , linux-mmc@vger.kernel.org, open list , "open list:BLUETOOTH SUBSYSTEM" , ath10k@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <1CA665D1-86F0-45A1-862D-17DAB3ABA974@holtmann.org> References: <20210817005507.1507580-1-dmitry.baryshkov@linaro.org> To: Dmitry Baryshkov X-Mailer: Apple Mail (2.3654.120.0.1.13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dmitry, > 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 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 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. Regards Marcel