linux-kernel - Re: [PATCH v3 2/5] dt-bindings: mips: mips-cm: Add a new compatible string for EyeQ6

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

Message-ID: <Z7hJVnJSg3C9lmLY@alpha.franken.de>
Date: Fri, 21 Feb 2025 10:37:26 +0100
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Gregory CLEMENT <gregory.clement@...tlin.com>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>, Rob Herring <robh@...nel.org>,
	Aleksandar Rikalo <arikalo@...il.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
	Théo Lebrun <theo.lebrun@...tlin.com>,
	Tawfik Bayouk <tawfik.bayouk@...ileye.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	"linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/5] dt-bindings: mips: mips-cm: Add a new compatible
 string for EyeQ6

On Tue, Jan 28, 2025 at 05:23:26PM +0100, Gregory CLEMENT wrote:
> > 在2025年1月27日一月 下午10:07，Rob Herring写道：
> >> On Mon, Jan 27, 2025 at 3:43 PM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
> >>>
> >>>
> >>>
> >>> 在2025年1月23日一月 上午11:01，Gregory CLEMENT写道：
> >>> > The CM3.5 used on EyeQ6 reports that Hardware Cache Initialization is
> >>> > complete, but in reality it's not the case. It also incorrectly
> >>> > indicates that Hardware Cache Initialization is supported. This new
> >>> > compatible string allows warning about this broken feature that cannot
> >>> > be detected at runtime.
> >>> >
> >>> > Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
> >>> > ---
> >>> >  Documentation/devicetree/bindings/mips/mti,mips-cm.yaml | 12 +++++++++++-
> >>> >  1 file changed, 11 insertions(+), 1 deletion(-)
> >>> >
> >>> > diff --git a/Documentation/devicetree/bindings/mips/mti,mips-cm.yaml
> >>> > b/Documentation/devicetree/bindings/mips/mti,mips-cm.yaml
> >>> > index
> >>> > 4324b2306535f1bf66c44b1f96be9094ee282041..d129d6382847768dc026336d8d2c7328b6b81f9b
> >>> > 100644
> >>> > --- a/Documentation/devicetree/bindings/mips/mti,mips-cm.yaml
> >>> > +++ b/Documentation/devicetree/bindings/mips/mti,mips-cm.yaml
> >>> > @@ -19,7 +19,12 @@ maintainers:
> >>> >
> >>> >  properties:
> >>> >    compatible:
> >>> > -    const: mti,mips-cm
> >>> > +    oneOf:
> >>> > +      - const: mti,mips-cm
> >>> > +      - const: mobileye,eyeq6-cm
> >>> > +        description:
> >>> > +          On EyeQ6 the HCI (Hardware Cache Initialization) information for
> >>> > +          the L2 cache in multi-cluster configuration is broken.
> >>> >
> >>> >    reg:
> >>> >      description:
> >>> > @@ -44,4 +49,9 @@ examples:
> >>> >        compatible = "mti,mips-cm";
> >>> >        reg = <0x1bde8000 0x8000>;
> >>> >      };
> >>> > +
> >>> > +  - |
> >>> > +    coherency-manager {
> >>> > +      compatible = "mobileye,eyeq6-cm";
> >>>
> >>> I think “mobileye,eyeq6-cm”, “mti,mips-cm” would describe the hardware better as eyeq6’s CM is just a special variant of mips-cm.
> >>
> >> Is s/w that only understands “mti,mips-cm” useful on eyeq6 chip? If
> >> so, I agree. If not, then a fallback compatible is not useful.
> >
> > Yes, mobileye,eyeq6-cm only enable an additional bug workaround in software.
> >
> 
> Having "mti,mips-cm" is not useful for the EyeQ6 chip. On the EyeQ6, we
> obtain all relevant information related to CM dynamically without
> needing this compatible string.
> 
> > The programming interfaces and so on remains unchanged.
> 
> Even without a compatible string, we are able to utilize the CM. At
> present, there is no node in the device tree, and apart from the
> hardware being faulty, we do not need it.
> 
> >
> > Also other firmware components like U-Boot doesn’t need to be aware of
> > eyeq6 variant.
> 
> It's the same for the firmware; they don't need to have "mti, mips-cm"
> information, as they can retrieve all they need dynamically.

so it the current patch version correct ? If yes and nothing else is
outstanding, I'm going to apply the series.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]