[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240412202216.GA14590@bhelgaas>
Date: Fri, 12 Apr 2024 15:22:16 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Jingoo Han <jingoohan1@...il.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof WilczyĆski <kw@...ux.com>,
Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
Marek Vasut <marek.vasut+renesas@...il.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Vidya Sagar <vidyas@...dia.com>,
Vignesh Raghavendra <vigneshr@...com>,
Richard Zhu <hongxing.zhu@....com>,
Lucas Stach <l.stach@...gutronix.de>,
Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
NXP Linux Team <linux-imx@....com>,
Minghuan Lian <minghuan.Lian@....com>,
Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Kishon Vijay Abraham I <kishon@...nel.org>,
Jesper Nilsson <jesper.nilsson@...s.com>,
Srikanth Thokala <srikanth.thokala@...el.com>,
Shawn Lin <shawn.lin@...k-chips.com>,
Heiko Stuebner <heiko@...ech.de>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org, Niklas Cassel <cassel@...nel.org>,
linux-arm-kernel@...s.com, linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v12 8/8] PCI: endpoint: Remove "core_init_notifier" flag
On Wed, Mar 27, 2024 at 02:43:37PM +0530, Manivannan Sadhasivam wrote:
> "core_init_notifier" flag is set by the glue drivers requiring refclk from
> the host to complete the DWC core initialization. Also, those drivers will
> send a notification to the EPF drivers once the initialization is fully
> completed using the pci_epc_init_notify() API. Only then, the EPF drivers
> will start functioning.
>
> For the rest of the drivers generating refclk locally, EPF drivers will
> start functioning post binding with them. EPF drivers rely on the
> 'core_init_notifier' flag to differentiate between the drivers.
> Unfortunately, this creates two different flows for the EPF drivers.
>
> So to avoid that, let's get rid of the "core_init_notifier" flag and follow
> a single initialization flow for the EPF drivers. This is done by calling
> the dw_pcie_ep_init_notify() from all glue drivers after the completion of
> dw_pcie_ep_init_registers() API. This will allow all the glue drivers to
> send the notification to the EPF drivers once the initialization is fully
> completed.
Thanks for doing this! I think this is a significantly nicer
solution than core_init_notifier was.
One question: both qcom and tegra194 call dw_pcie_ep_init_registers()
from an interrupt handler, but they register that handler in a
different order with respect to dw_pcie_ep_init().
I don't know what actually starts the process that leads to the
interrupt, but if it's dw_pcie_ep_init(), then one of these (qcom, I
think) must be racy:
qcom_pcie_ep_probe
dw_pcie_ep_init <- A
qcom_pcie_ep_enable_irq_resources
devm_request_threaded_irq(qcom_pcie_ep_perst_irq_thread) <- B
qcom_pcie_ep_perst_irq_thread
qcom_pcie_perst_deassert
dw_pcie_ep_init_registers
tegra_pcie_dw_probe
tegra_pcie_config_ep
devm_request_threaded_irq(tegra_pcie_ep_pex_rst_irq) <- B
dw_pcie_ep_init <- A
tegra_pcie_ep_pex_rst_irq
pex_ep_event_pex_rst_deassert
dw_pcie_ep_init_registers
Whatever the right answer is, I think qcom and tegra194 should both
order dw_pcie_ep_init() and the devm_request_threaded_irq() the same
way.
Bjorn
Powered by blists - more mailing lists