From: Rob Herring <robh+dt@kernel.org>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: "Kalle Valo" <kvalo@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Conor Dooley" <conor+dt@kernel.org>,
"Bjorn Andersson" <andersson@kernel.org>,
"Konrad Dybcio" <konrad.dybcio@linaro.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Heiko Stuebner" <heiko@sntech.de>,
"Jernej Skrabec" <jernej.skrabec@gmail.com>,
"Chris Morgan" <macromorgan@hotmail.com>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Geert Uytterhoeven" <geert+renesas@glider.be>,
"Arnd Bergmann" <arnd@arndb.de>,
"Neil Armstrong" <neil.armstrong@linaro.org>,
"Nícolas F . R . A . Prado" <nfraprado@collabora.com>,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Peng Fan" <peng.fan@nxp.com>,
"Robert Richter" <rrichter@amd.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Jonathan Cameron" <Jonathan.Cameron@huawei.com>,
"Terry Bowman" <terry.bowman@amd.com>,
"Lukas Wunner" <lukas@wunner.de>,
"Huacai Chen" <chenhuacai@kernel.org>,
"Alex Elder" <elder@linaro.org>,
"Srini Kandagatla" <srinivas.kandagatla@linaro.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Abel Vesa" <abel.vesa@linaro.org>,
linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>
Subject: Re: [PATCH 0/9] PCI: introduce the concept of power sequencing of PCIe devices
Date: Thu, 18 Jan 2024 08:29:01 -0600 [thread overview]
Message-ID: <CAL_Jsq+0xb-otvjkbLqB8gNKadVqnigwGB_k+VGrj740Y6wxjg@mail.gmail.com> (raw)
In-Reply-To: <20240117160748.37682-1-brgl@bgdev.pl>
On Wed, Jan 17, 2024 at 10:08 AM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> The responses to the RFC were rather positive so here's a proper series.
Thanks for tackling this.
> During last year's Linux Plumbers we had several discussions centered
> around the need to power-on PCI devices before they can be detected on
> the bus.
>
> The consensus during the conference was that we need to introduce a
> class of "PCI slot drivers" that would handle the power-sequencing.
>
> After some additional brain-storming with Manivannan and the realization
> that DT maintainers won't like adding any "fake" nodes not representing
> actual devices, we decided to reuse existing PCI infrastructure.
Thank you. :)
> The general idea is to instantiate platform devices for child nodes of
> the PCIe port DT node. For those nodes for which a power-sequencing
> driver exists, we bind it and let it probe. The driver then triggers a
> rescan of the PCI bus with the aim of detecting the now powered-on
> device. The device will consume the same DT node as the platform,
> power-sequencing device. We use device links to make the latter become
> the parent of the former.
>
> The main advantage of this approach is not modifying the existing DT in
> any way and especially not adding any "fake" platform devices.
Suspend/resume has been brought up already, but I disagree we can
worry about that later unless there is and always will be no power
sequencing during suspend/resume for all devices ever. Given the
supplies aren't standard, it wouldn't surprise me if standard PCI
power management isn't either. The primary issue I see with this
design is we will end up with 2 drivers doing the same power
sequencing: the platform driver for initial power on and the device's
PCI driver for suspend/resume.
Rob
next prev parent reply other threads:[~2024-01-18 14:29 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-17 16:07 [PATCH 0/9] PCI: introduce the concept of power sequencing of PCIe devices Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 1/9] arm64: dts: qcom: qrb5165-rb5: describe the WLAN module of QCA6390 Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 2/9] arm64: dts: qcom: sm8550-qrd: add Wifi nodes Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 3/9] arm64: dts: qcom: sm8650-qrd: " Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 4/9] PCI: create platform devices for child OF nodes of the port node Bartosz Golaszewski
2024-01-17 16:22 ` Dan Williams
2024-01-18 13:11 ` Bartosz Golaszewski
2024-01-17 16:45 ` Greg Kroah-Hartman
2024-01-18 10:58 ` Bartosz Golaszewski
2024-01-18 11:15 ` Greg Kroah-Hartman
2024-01-30 21:54 ` Bjorn Andersson
2024-01-31 11:04 ` Bartosz Golaszewski
2024-02-02 0:03 ` Bjorn Andersson
2024-02-02 4:50 ` Jeff Johnson
2024-02-02 10:02 ` Re: " Bartosz Golaszewski
2024-02-07 16:32 ` Bartosz Golaszewski
2024-02-14 15:34 ` Greg Kroah-Hartman
2024-01-17 16:07 ` [PATCH 5/9] PCI: hold the rescan mutex when scanning for the first time Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 6/9] PCI/pwrseq: add pwrseq core code Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 7/9] dt-bindings: wireless: ath11k: describe QCA6390 Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 8/9] dt-bindings: wireless: ath11k: describe WCN7850 Bartosz Golaszewski
2024-01-17 18:07 ` Kalle Valo
2024-01-17 20:01 ` Bartosz Golaszewski
2024-01-17 16:07 ` [PATCH 9/9] PCI/pwrseq: add a pwrseq driver for QCA6390 Bartosz Golaszewski
2024-01-18 5:49 ` Kalle Valo
2024-01-18 17:50 ` Konrad Dybcio
2024-01-17 17:53 ` [PATCH 0/9] PCI: introduce the concept of power sequencing of PCIe devices Neil Armstrong
2024-01-17 18:16 ` Dmitry Baryshkov
2024-01-18 18:53 ` Dmitry Baryshkov
2024-01-19 11:52 ` Bartosz Golaszewski
2024-01-19 12:31 ` Dmitry Baryshkov
2024-01-19 13:35 ` brgl
2024-01-19 14:07 ` Dmitry Baryshkov
2024-01-19 14:11 ` Bartosz Golaszewski
2024-01-19 14:48 ` Bartosz Golaszewski
2024-01-19 16:34 ` Lukas Wunner
2024-01-19 16:45 ` Rob Herring
2024-01-18 14:29 ` Rob Herring [this message]
2024-01-18 16:38 ` Bartosz Golaszewski
2024-01-18 16:47 ` Manivannan Sadhasivam
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