linux-kernel - Re: [PATCH v3 00/12] usb: dwc3: qcom: Flatten dwc3 structure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAL_Jsq+4qzfy3kY+8LwPvGs4FkFKoregTAYu4-buJQZHkqJwyA@mail.gmail.com>
Date: Wed, 15 Jan 2025 12:51:42 -0600
From: Rob Herring <robh@...nel.org>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Bjorn Andersson <bjorn.andersson@....qualcomm.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Felipe Balbi <balbi@...nel.org>, 
	Wesley Cheng <quic_wcheng@...cinc.com>, Saravana Kannan <saravanak@...gle.com>, 
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Konrad Dybcio <konradybcio@...nel.org>, Frank Li <Frank.li@....com>, linux-arm-msm@...r.kernel.org, 
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 00/12] usb: dwc3: qcom: Flatten dwc3 structure

On Tue, Jan 14, 2025 at 5:04 PM Bjorn Andersson <andersson@...nel.org> wrote:
>
> On Tue, Jan 14, 2025 at 11:44:52AM -0600, Rob Herring wrote:
> > On Mon, Jan 13, 2025 at 09:11:33PM -0800, Bjorn Andersson wrote:
> > > The USB IP-block found in most Qualcomm platforms is modelled in the
> > > Linux kernel as 3 different independent device drivers, but as shown by
> > > the already existing layering violations in the Qualcomm glue driver
> > > they can not be operated independently.
> > >
> > > With the current implementation, the glue driver registers the core and
> > > has no way to know when this is done. As a result, e.g. the suspend
> > > callbacks needs to guard against NULL pointer dereferences when trying
> > > to peek into the struct dwc3 found in the drvdata of the child.
> > >
> > > Missing from the upstream Qualcomm USB support is proper handling of
> > > role switching, in which the glue needs to be notified upon DRD mode
> > > changes. Several attempts has been made through the years to register
> > > callbacks etc, but they always fall short when it comes to handling of
> > > the core's probe deferral on resources etc.
> > >
> > > Furhtermore, the DeviceTree binding is a direct representation of the
> > > Linux driver model, and doesn't necessarily describe "the USB IP-block".
> > >
> > > This series therefor attempts to flatten the driver split, and operate
> > > the glue and core out of the same platform_device instance. And in order
> > > to do this, the DeviceTree representation of the IP block is flattened.
> > >
> > > To avoid littering the dwc3-qcom driver with the migration code - which
> > > we should be able to drop again in a LTS or two - this is now placed in
> > > drivers/of/overlays.
> > >
> > > A patch to convert a single platform - sc8280xp - is included in the
> > > series. The broader conversion will be submitted in a follow up series.
> >
> > Is it not possible to use the same overlays also fixup the .dts files at
> > build time?
> >
>
> I presume so. What would the benefit of that be, over fixing up the
> source asap?

The overlays would live with all the other dts files (I think kbuild
can add built-in dtbs from arch/*/boot/dts/). We can test at build
time they actually apply, and ensure the new dtb matches what the
fixup overlay creates.

Rob