linux-kernel - Re: [PATCH RESEND,v6 2/8] dt-bindings: mailbox: Add property for CMDQ secure driver

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Message-ID: <9c39bbb1b1363887aa55cfe4118683ee97f9f875.camel@mediatek.com>
Date: Tue, 28 May 2024 15:10:11 +0000
From: Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>
To: "conor@...nel.org" <conor@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
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	Singo Chang (張興國) <Singo.Chang@...iatek.com>,
	Jason-ch Chen (陳建豪)
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	<jassisinghbrar@...il.com>, "angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH RESEND,v6 2/8] dt-bindings: mailbox: Add property for CMDQ
 secure driver

On Tue, 2024-05-28 at 15:59 +0100, Conor Dooley wrote:
> On Tue, May 28, 2024 at 02:38:46PM +0000, Jason-JH Lin (林睿祥) wrote:
> > Hi Conor,
> > 
> > On Mon, 2024-05-27 at 18:36 +0100, Conor Dooley wrote:
> > > On Sun, May 26, 2024 at 10:44:37PM +0800, Jason-JH.Lin wrote:
> > > > 1. Add mboxes property to define a GCE loopping thread as a
> > > > secure
> > > > IRQ
> > > > handler.
> > > > The CMDQ secure driver requests a mbox channel and sends a
> > > > looping
> > > > command to the GCE thread. The looping command will wait for a
> > > > secure
> > > > packet done event signal from secure world and then jump back
> > > > to
> > > > the
> > > > first instuction. Each time it waits for an event, it notifies
> > > > the
> > > > CMDQ driver to perform the same action as the IRQ handler.
> > > > 
> > > > 2. Add gce-events property from gce-props.yaml to define a
> > > > secure packet done signal in secure world.
> > > > There are 1024 events IDs for GCE to use to execute
> > > > instructions in
> > > > the specific event happened. These events could be signaled by
> > > > HW
> > > > or SW
> > > > and their value would be different in different SoC because of
> > > > HW
> > > > event
> > > > IDs distribution range from 0 to 1023.
> > > > If we set a static event ID: 855 for mt8188, it might be
> > > > conflict
> > > > the
> > > > event ID original set in mt8195.
> > > 
> > > Two different SoCs, two different compatibles, no problem.
> > > I'm almost certain you previously told me that the firmware
> > > changing
> > > could result in a different event ID, but I see no mention of
> > > that
> > > here.
> > 
> > Yes, it could be, but we don't use it that way.
> > 
> > > The commit messages makes it seem like this can be determined by
> > > the
> > > compatible, so either give me a commit message that explains why
> > > the
> > > compatible is not sufficient or drop the patch.
> > > 
> > 
> > Yes, this can be determined by compatible in CMDQ mailbox driver,
> > so I think it's possible to put this in the CMDQ mailbox driver
> > data
> > and configure by different SoC.
> > 
> > The problem is these events are defined in include/dt-
> > bindings/mailbox/mediatek,mt8188-gce.h and include/dt-
> > bindings/gce/mt8195-gce.h.
> > I can only use them in their mt8188.dts or mt8195.dts.
> > 
> > If I want to use the same event define in 2 different headers in
> > the
> > same CMDQ mailbox driver, I think I just can parse their dts to get
> > the
> > corresponding one.
> > Do you know how to generally deal with this problem?
> > Or I can just use the number of event ID in driver data without the
> > event define in dt-bindings header.
> 
> I don't think I really understand the problem. You get the
> channelid/event data from the match data, right? Is the problem that
> both files define the same "word" to mean different numbers? 

Yes, I mean the same "event define" with different event ID numbers in
different SoC headers.

> In that
> case, just define the numbers locally in the driver, you don't need
> to
> include a binding header when there's no data sharing between dts and
> kernel.

OK, I'll do that and drop this patch.
Thanks~

Regards,
Jason-JH.Lin