linux-kernel - Re: [PATCH] mfd: omap-usb-host: fix OF populate on driver rebind

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Message-ID: <20260109174905.GB1893402@google.com>
Date: Fri, 9 Jan 2026 17:49:05 +0000
From: Lee Jones <lee@...nel.org>
To: Andreas Kemnade <andreas@...nade.info>
Cc: Johan Hovold <johan@...nel.org>, Aaro Koskinen <aaro.koskinen@....fi>,
	Kevin Hilman <khilman@...libre.com>,
	Roger Quadros <rogerq@...nel.org>, Tony Lindgren <tony@...mide.com>,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] mfd: omap-usb-host: fix OF populate on driver rebind

On Fri, 09 Jan 2026, Andreas Kemnade wrote:

> On Fri, 9 Jan 2026 18:18:39 +0100
> Andreas Kemnade <andreas@...nade.info> wrote:
> 
> > On Fri, 9 Jan 2026 16:39:39 +0000
> > Lee Jones <lee@...nel.org> wrote:
> > 
> > > On Fri, 09 Jan 2026, Lee Jones wrote:
> > >   
> > > > On Fri, 19 Dec 2025, Johan Hovold wrote:
> > > >     
> > > > > Since commit c6e126de43e7 ("of: Keep track of populated platform
> > > > > devices") child devices will not be created by of_platform_populate()
> > > > > if the devices had previously been deregistered individually so that the
> > > > > OF_POPULATED flag is still set in the corresponding OF nodes.
> > > > > 
> > > > > Switch to using of_platform_depopulate() instead of open coding so that
> > > > > the child devices are created if the driver is rebound.
> > > > > 
> > > > > Fixes: c6e126de43e7 ("of: Keep track of populated platform devices")
> > > > > Cc: stable@...r.kernel.org	# 3.16
> > > > > Signed-off-by: Johan Hovold <johan@...nel.org>
> > > > > ---
> > > > >  drivers/mfd/omap-usb-host.c | 6 ++++--
> > > > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
> > > > > index a77b6fc790f2..4d29a6e2ed87 100644
> > > > > --- a/drivers/mfd/omap-usb-host.c
> > > > > +++ b/drivers/mfd/omap-usb-host.c
> > > > > @@ -819,8 +819,10 @@ static void usbhs_omap_remove(struct platform_device *pdev)
> > > > >  {
> > > > >  	pm_runtime_disable(&pdev->dev);
> > > > >  
> > > > > -	/* remove children */
> > > > > -	device_for_each_child(&pdev->dev, NULL, usbhs_omap_remove_child);
> > > > > +	if (pdev->dev.of_node)
> > > > > +		of_platform_depopulate(&pdev->dev);    
> > > > 
> > > > devm_of_platform_populate()?
> > > >     
> > > > > +	else
> > > > > +		device_for_each_child(&pdev->dev, NULL, usbhs_omap_remove_child);    
> > > > 
> > > > What on earth is this driver even doing in MFD?
> > > > 
> > > > Nightmare - quick dig, bury it!    
> > > 
> > > Is the old platform method even supported anymore?
> > > 
> > > $ git grep \"usbhs_omap\""
> > > drivers/mfd/omap-usb-host.c:#define USBHS_DRIVER_NAME   "usbhs_omap"
> > >   
> > :~/linux/arch/arm/boot/dts/ti/omap$ grep ti,usbhs-host *.dtsi
> > omap3.dtsi:			compatible = "ti,usbhs-host";
> > omap4-l4.dtsi:				compatible = "ti,usbhs-host";
> > omap5-l4.dtsi:				compatible = "ti,usbhs-host";
> > 
> > So it is still in use.
> > 
> ok, that was just answering in panic mode to prevent removal of a needed
> driver. Reading it again: I think omap2/3/4/5 without devicetree will not work
> anyway, so we can remove anything done on !dev->of_node.

Okay, leave it with me.

-- 
Lee Jones [李琼斯]