linux-kernel - Re: [PATCH 2/5] PCI: endpoint: Introduce 'epc_deinit' event and notify the EPF drivers

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Message-ID: <20240611220640.GA1001976@bhelgaas>
Date: Tue, 11 Jun 2024 17:06:40 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Vignesh Raghavendra <vigneshr@...com>,
	Siddharth Vadapalli <s-vadapalli@...com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.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>,
	Minghuan Lian <minghuan.Lian@....com>,
	Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Srikanth Thokala <srikanth.thokala@...el.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>,
	Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	linux-omap@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev, linuxppc-dev@...ts.ozlabs.org,
	linux-arm-kernel@...s.com, linux-arm-msm@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
	mhi@...ts.linux.dev, Niklas Cassel <cassel@...nel.org>
Subject: Re: [PATCH 2/5] PCI: endpoint: Introduce 'epc_deinit' event and
 notify the EPF drivers

On Thu, Jun 06, 2024 at 12:56:35PM +0530, Manivannan Sadhasivam wrote:
> As like the 'epc_init' event, that is used to signal the EPF drivers about
> the EPC initialization, let's introduce 'epc_deinit' event that is used to
> signal EPC deinitialization.
> 
> The EPC deinitialization applies only when any sort of fundamental reset
> is supported by the endpoint controller as per the PCIe spec.
> 
> Reference: PCIe Base spec v5.0, sections 4.2.4.9.1 and 6.6.1.

PCIe r6.0, sec 4.2.5.9.1 and 6.6.1.

(Not 4.2.4.9.1, which no longer exists in r6.x)

> Currently, some EPC drivers like pcie-qcom-ep and pcie-tegra194 support
> PERST# as the fundamental reset. So the 'deinit' event will be notified to
> the EPF drivers when PERST# assert happens in the above mentioned EPC
> drivers.
> 
> The EPF drivers, on receiving the event through the epc_deinit() callback
> should reset the EPF state machine and also cleanup any configuration that
> got affected by the fundamental reset like BAR, DMA etc...
> 
> This change also warrants skipping the cleanups in unbind() if already done
> in epc_deinit().
> 
> Reviewed-by: Niklas Cassel <cassel@...nel.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>