From: Michael Walle <michael@walle.cc>
To: "Sahil Malhotra (OSS)" <sahil.malhotra@oss.nxp.com>
Cc: "ZHIZHIKIN Andrey" <andrey.zhizhikin@leica-geosystems.com>,
"Clément Faure" <clement.faure@nxp.com>,
"Gaurav Jain" <gaurav.jain@nxp.com>,
"Pankaj Gupta" <pankaj.gupta@nxp.com>,
"Priyanka Jain" <priyanka.jain@nxp.com>,
u-boot@lists.denx.de, "Varun Sethi" <V.Sethi@nxp.com>,
"Ye Li" <ye.li@nxp.com>
Subject: Re: [PATCH 1/2] fsl-layerscape: add dtb overlay feature
Date: Thu, 06 Jan 2022 08:40:21 +0100 [thread overview]
Message-ID: <b0359ed615380ac440435b3ba99dc911@walle.cc> (raw)
In-Reply-To: <VI1PR04MB53279E27A4357ABD669357AA824C9@VI1PR04MB5327.eurprd04.prod.outlook.com>
Hi Sahil,
Am 2022-01-06 07:09, schrieb Sahil Malhotra (OSS):
>> I don't know I follow. u-boot and linux should have the same device
>> tree;
>> regardless if that device is used or not. So applying the overlay just
>> for linux isn't
>> enough here.
> Ok, I don't think that as of now, in all platforms uboot and linux
> have same devie
> tree.
That doesn't mean it is ok to diverge again. I put a lot of effort in
syncing uboot's LS1028A device tree with linux.
> But I will try to address your concern, but I don’t know how to apply
> overlay to
> dtb which is embedded in u-boot binary, Can you please point me to one
> reference
> which is doing this thing, I will take reference from there.
Sorry I can't advise you with that. There is board_fix_fdt() maybe
that will help. But I'm not conviced this is the correct approach,
see below.
>> > We don't use DTB in OP-TEE, but when we use CAAM in OP-TEE, OP-TEE
>> > reserves One Job Ring for its use and that is communicated to Kernel
>> > using DTB overlay.
>> >
>> >> what if the overlay doesn't match the dtb?
>> > I didn't get this point, can you please elaborate a little.
>>
>> You are merging a dtb fragment with an unknown dtb, right? Who says
>> they
>> match? you might have an old dtb where the supplied dtb fragment
>> doesn't
>> make any sense.
>>
>> I might be missing something here. Eg. where is the linux dtb supposed
>> to come
>> from? This patchset is really missing an example and a description how
>> things
>> should work.
> If supplied DTB does not match with DTB overlay fragment. then overlay
> will not get applied.
I don't think this is what happens here. fdt_overlay_apply() will
mark the fdt as damaged and there will be no fdt at all.
> We don't have any control on where user picks the DTB, but we can only
> make sure DTB
> overlay feature must work with DTBs which are upstreamed
> If user makes its own customized DTB, we cannot make sure that things
> will work.
Again. Is there any documentation on how this should all work
together? Where does optee get its device tree from? Shouldn't
it be the same device tree as u-boot and linux? Shouldn't optee
modify the device tree in place before jumping back to u-boot?
Andrey, do you know how this works on imx?
-michael
next prev parent reply other threads:[~2022-01-06 7:40 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 6:09 RE:Re: [PATCH 1/2] fsl-layerscape: add dtb overlay feature Sahil Malhotra (OSS)
2022-01-06 7:40 ` Michael Walle [this message]
2022-02-04 11:27 ` Sahil Malhotra (OSS)
2022-02-24 10:59 ` Sahil Malhotra (OSS)
2022-02-24 12:33 ` Michael Walle
2022-01-06 7:47 ` François Ozog
2022-01-31 8:07 ` [EXT] " Sahil Malhotra (OSS)
-- strict thread matches above, loose matches on Subject: below --
2021-11-17 6:23 Sahil Malhotra
2021-11-17 7:53 ` Michael Walle
2021-11-17 18:11 ` Sahil Malhotra (OSS)
2021-11-17 18:20 ` Michael Walle
2021-11-29 11:55 ` Sahil Malhotra (OSS)
2021-11-29 17:47 ` Michael Walle
2021-12-08 6:12 ` Sahil Malhotra (OSS)
2021-12-08 10:13 ` ZHIZHIKIN Andrey
2021-12-10 6:33 ` Sahil Malhotra (OSS)
2021-12-17 6:19 ` Sahil Malhotra (OSS)
2021-12-17 7:27 ` Michael Walle
2021-12-20 12:52 ` Michael Walle
2021-12-10 7:38 ` François Ozog
2021-11-16 10:16 Sahil Malhotra
2021-11-16 8:34 Sahil Malhotra
2021-11-16 8:30 Sahil Malhotra
2021-11-16 6:49 Sahil Malhotra
2021-11-16 6:46 Sahil Malhotra
2021-11-16 6:37 Sahil Malhotra
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