Re: [PATCH RESEND,v6 8/8] soc: mediatek: mtk-cmdq: Add secure cmdq_pkt APIs

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Jason:

On Tue, 2024-05-28 at 15:33 +0000, Jason-JH Lin (林睿祥) wrote:
> Hi CK,
> 
> On Tue, 2024-05-28 at 03:01 +0000, CK Hu (胡俊光) wrote:
> > Hi, Jason:
> > 
> > On Sun, 2024-05-26 at 22:44 +0800, Jason-JH.Lin wrote:
> > > Open secure cmdq_pkt APIs to support executing commands in secure
> > > world.
> > > 
> > > 1. Add cmdq_sec_pkt_alloc_sec_data(), cmdq_sec_pkt_free_sec_data()
> > > and
> > >    cmdq_sec_pkt_set_data() to prepare the sec_data in cmdq_pkt that
> > > will
> > >    be referenced in the secure world.
> > > 
> > > 2. Add cmdq_sec_insert_backup_cookie() and cmdq_sec_pkt_write() to
> > >    generate commands that need to be executed in the secure world.
> > >    In cmdq_sec_pkt_write(), we need to prepare the metadata to
> > > store
> > >    buffer offset of the secure buffer handle because secure world
> > > can
> > >    only translate the start address of secure buffer by secure
> > > handle.
> > > 
> > > Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> > > Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
> > > ---
> > 
> > [snip]
> > 
> > > +
> > > +int cmdq_sec_pkt_set_data(struct cmdq_pkt *pkt, enum
> > > cmdq_sec_scenario scenario)
> > > +{
> > > +	struct cmdq_sec_data *sec_data;
> > > +	int ret;
> > > +
> > > +	if (!pkt) {
> > > +		pr_err("invalid pkt:%p", pkt);
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	ret = cmdq_sec_pkt_alloc_sec_data(pkt);
> > > +	if (ret < 0)
> > > +		return ret;
> > > +
> > > +	pr_debug("[%s %d] pkt:%p sec_data:%p scen:%u",
> > > +		 __func__, __LINE__, pkt, pkt->sec_data, scenario);
> > > +
> > > +	sec_data = (struct cmdq_sec_data *)pkt->sec_data;
> > > +	sec_data->scenario = scenario;
> > > +
> > > +	return 0;
> > > +}
> > 
> > What does cmdq_sec_pkt_set_data() exactly do? It seems to
> > enable/disable protection on hardware of certain pipeline.
> > In future, you would use secure GCE for normal video and secure
> > video.
> > Would you also use secure display pipeline for both normal video and
> > secure video?
> 
> I think I won't do that.
> 
> > If so, I think we could drop this function because the hardware is
> > always protected.
> > 
> 
> But we will use ENABLE and DISABLE scenario to notify secure world to
> enable/disable the protection of secure buffer and register by setting
> larb port and DAPC.
> 
> If there is secure memory output scenario (WiFi Display scenario) in
> the same display pipeline as main display scenario, we will need to use
> this scenario to differentiate them.

This API looks no relation with CMDQ. All the job is that display control larb, dapc to turn on/off protection.
All the process is done by CPU not GCE, right?
If so, this API should be provided by display TA not CMDQ TA.

Regards,
CK

> 
> Regards,
> Jason-JH.Lin
> 
> > Regards,
> > CK
> > 
> > > +EXPORT_SYMBOL_GPL(cmdq_sec_pkt_set_data);
> > > +