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 C25CEC4338F for ; Sat, 21 Aug 2021 06:50:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A86DE61156 for ; Sat, 21 Aug 2021 06:50:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232469AbhHUGvY convert rfc822-to-8bit (ORCPT ); Sat, 21 Aug 2021 02:51:24 -0400 Received: from coyote.holtmann.net ([212.227.132.17]:54252 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231738AbhHUGvX (ORCPT ); Sat, 21 Aug 2021 02:51:23 -0400 Received: from smtpclient.apple (p5b3d23f8.dip0.t-ipconnect.de [91.61.35.248]) by mail.holtmann.org (Postfix) with ESMTPSA id D102DCED43; Sat, 21 Aug 2021 08:50:40 +0200 (CEST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\)) Subject: Re: [RFC PATCH 00/15] create power sequencing subsystem From: Marcel Holtmann In-Reply-To: Date: Sat, 21 Aug 2021 08:50:40 +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: <551758F2-0B00-4DEB-92C9-37472E46B75D@holtmann.org> References: <20210817005507.1507580-1-dmitry.baryshkov@linaro.org> <1CA665D1-86F0-45A1-862D-17DAB3ABA974@holtmann.org> To: Dmitry Baryshkov X-Mailer: Apple Mail (2.3654.100.0.2.22) Precedence: bulk List-ID: X-Mailing-List: linux-wireless@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 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? I was missing enough hardware to test it on and frankly I hoped that someone would pick up this work. The HCI line discipline “hack” needs to be removed soon. It is complicated, cumbersome and has a bunch of issues with locking. Mind you that originated in 2.4.6 kernel and is at its core bit-rotting. If you manage to put QCA support into a separate btqcauart driver, that would be awesome. The btmtkuart driver is another example where Mediatek got its own serdev based driver. Regards Marcel