linux-kernel - Re: [PATCH v9 07/10] PCI: dwc: ep: Remove "core_init

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Date: Fri, 8 Mar 2024 15:14:04 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Niklas Cassel <cassel@...nel.org>
Cc: Jingoo Han <jingoohan1@...il.com>,
	Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <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>,
	Kishon Vijay Abraham I <kishon@...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>,
	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,
	linux-arm-kernel@...s.com, Frank Li <Frank.Li@....com>
Subject: Re: [PATCH v9 07/10] PCI: dwc: ep: Remove "core_init_notifier" flag

On Fri, Mar 08, 2024 at 09:48:07AM +0100, Niklas Cassel wrote:
> On Fri, Mar 08, 2024 at 11:08:29AM +0530, Manivannan Sadhasivam wrote:
> > On Thu, Mar 07, 2024 at 10:09:06PM +0100, Niklas Cassel wrote:
> > > On Mon, Mar 04, 2024 at 02:52:19PM +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.
> > > > 
> > > > Only difference here is that, the drivers requiring refclk from host will
> > > > send the notification once refclk is received, while others will send it
> > > > during probe time itself.
> > > > 
> > > > Reviewed-by: Frank Li <Frank.Li@....com>
> > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > > ---
> > > 
> > > You have removed the .core_init_notifier from EPC drivers,
> > > but the callback in EPF drivers is still called .core_init.
> > > 
> > > Yes, this was a confusing name even before this patch, but
> > > after this patch, it is probably even worse :)
> > > 
> > > The callback should be named from the perspective of EPF drivers IMO.
> > > .core_init sounds like a EPF driver should initialize the core.
> > > (But that is of course done by the EPC driver.)
> > > 
> > > The .link_up() callback name is better, the EPF driver is informed
> > > that the link is up.
> > > 
> > > Perhaps we could rename .core_init to .core_up ?
> > > 
> > > It tells the EPF drivers that the core is now up.
> > > (And the EPF driver can configure the BARs.)
> > > 
> > 
> > I don't disagree :) I thought about it but then decided to not extend the scope
> > of this series further. So saved that for next series.
> > 
> > But yeah, it is good to clean it up here itself.
> 
> If you intend to create a .core_deinit or .core_down (or whatever name
> you decide on), perhaps it is better to leave this cleanup to be part
> of that same series?
> 

I already added a patch. So let's do it here itself :)

- Mani

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