From: Rob Herring <robh@kernel.org>
To: Hongxing Zhu <hongxing.zhu@nxp.com>
Cc: "l.stach@pengutronix.de" <l.stach@pengutronix.de>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"broonie@kernel.org" <broonie@kernel.org>,
"lorenzo.pieralisi@arm.com" <lorenzo.pieralisi@arm.com>,
"jingoohan1@gmail.com" <jingoohan1@gmail.com>,
"festevam@gmail.com" <festevam@gmail.com>,
"francesco.dolcini@toradex.com" <francesco.dolcini@toradex.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH v8 6/8] PCI: dwc: Add dw_pcie_host_ops.host_exit() callback
Date: Mon, 4 Apr 2022 09:39:33 -0500 [thread overview]
Message-ID: <YksDJfterGl9uPjs@robh.at.kernel.org> (raw)
In-Reply-To: <AS8PR04MB8676A8E85BBDA507481E12C78CE39@AS8PR04MB8676.eurprd04.prod.outlook.com>
On Sat, Apr 02, 2022 at 03:03:00AM +0000, Hongxing Zhu wrote:
> > -----Original Message-----
> > From: Rob Herring <robh@kernel.org>
> > Sent: 2022年4月2日 4:44
> > To: Hongxing Zhu <hongxing.zhu@nxp.com>
> > Cc: l.stach@pengutronix.de; bhelgaas@google.com; broonie@kernel.org;
> > lorenzo.pieralisi@arm.com; jingoohan1@gmail.com; festevam@gmail.com;
> > francesco.dolcini@toradex.com; linux-pci@vger.kernel.org;
> > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> > kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>
> > Subject: Re: [PATCH v8 6/8] PCI: dwc: Add dw_pcie_host_ops.host_exit()
> > callback
> >
> > On Fri, Feb 25, 2022 at 11:44:25AM +0800, Richard Zhu wrote:
> > > When the link never comes up after ->host_init(), some drivers,
> > > especially those that don't support hotplug, want to turn off clocks
> > > and power supplies.
> >
> > Isn't supporting hotplug or not a board level decision? And hotplug doesn't
> > have to mean physical plug/unplug. For example, you could have a soldered
> > down PCIe device which needs regulators, resets, clocks, etc.
> > for that device to be initialized before the link comes up. If that device is
> > handled by a module loaded some time later, then the link may be down when
> > you probe.
> >
> > I think the way this all needs to work is with runtime PM. If that's all in place,
> > then either you shutdown clocks/power on timeout or via sysfs suspend. If
> > there's a child device, then that should prevent suspending.
> Hi Rob:
> Thanks a lot for your review comments.
> Understand what you mean.
> i.MX PCIe doesn't support hot-plug from chip design view.
The scenario I described is not hotplug.
> The ops.host_exit() callback is invoked only when the iMX PCIe driver hooked
> callback ops->start_link return an error.
> For the platforms, that support the hot-plug feature, they can just return one
> zero from their own ops->start_link.
You cannot have a per board start_link().
> In the current situation, i.MX PCIe does just return one zero when probe failed.
> See the discussion and commit issued by Fabio below.
> https://patchwork.kernel.org/project/linux-pci/patch/1641368602-20401-6-git-send-email-hongxing.zhu@nxp.com/
> https://patchwork.ozlabs.org/project/linux-pci/patch/20220106103645.2790803-1-festevam@gmail.com/
That's a stable fix and different discussion.
> > > Add a new ->host_exit() callback in dw_pcie_host_ops so these drivers
> > > can clean up if ->host_init() fails.
> >
> > I'm not really a fan of adding more ops nor the ops which aren't too specific
> > about what they do. 'init' and 'exit' can be anything. I'd rather see more
> > specific ops with the DWC core driver in charge of sequence of operations and
> > the state.
> Understand.
You don't seem to...
> i.MX PCIe can't handle the error exit properly in this case by itself. So I
> add one more ops.host_exit() in this series.
>
> Best Regards
> Richard Zhu
> >
> > Rob
next prev parent reply other threads:[~2022-04-04 14:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 3:44 [PATCH v8 0/8] PCI: imx6: refine codes and add compliance tests mode support Richard Zhu
2022-02-25 3:44 ` [PATCH v8 1/8] PCI: imx6: Encapsulate the clock enable into one standalone function Richard Zhu
2022-02-25 3:44 ` [PATCH v8 2/8] PCI: imx6: Add the error propagation from host_init Richard Zhu
2022-02-25 3:44 ` [PATCH v8 3/8] PCI: imx6: Move imx6_pcie_clk_disable() earlier Richard Zhu
2022-02-25 3:44 ` [PATCH v8 4/8] PCI: imx6: Disable iMX6QDL PCIe REF clock when disable PCIe clocks Richard Zhu
2022-02-25 3:44 ` [PATCH v8 5/8] PCI: imx6: Refine the regulator usage Richard Zhu
2022-02-25 9:43 ` Francesco Dolcini
2022-02-28 3:43 ` Hongxing Zhu
2022-03-04 7:45 ` Francesco Dolcini
2022-03-04 8:44 ` Hongxing Zhu
2022-02-25 3:44 ` [PATCH v8 6/8] PCI: dwc: Add dw_pcie_host_ops.host_exit() callback Richard Zhu
2022-04-01 20:43 ` Rob Herring
2022-04-02 3:03 ` Hongxing Zhu
2022-04-04 14:39 ` Rob Herring [this message]
2022-04-05 3:15 ` Hongxing Zhu
2022-02-25 3:44 ` [PATCH v8 7/8] PCI: imx6: Disable clocks and regulators after link is down Richard Zhu
2022-02-25 3:44 ` [PATCH v8 8/8] PCI: imx6: Add compliance tests mode support Richard Zhu
2022-04-01 20:26 ` Rob Herring
2022-04-02 3:03 ` Hongxing Zhu
2022-03-14 5:26 ` [PATCH v8 0/8] PCI: imx6: refine codes and add " Hongxing Zhu
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