Hi Sahil,
Am 2021-12-23 09:46, schrieb Sahil Malhotra (OSS):
-Original Message-
From: U-Boot On Behalf Of Michael Walle
Sent: Monday, December 20, 2021 6:23 PM
To: Sahil Malhotra (OSS)
Cc: ZHIZHIKIN Andrey ; Clément
Faure ; Gaurav Jain ;
Pankaj Gupta ; Priyanka Jain
; u-boot@lists.denx.de; Varun Sethi
; Ye Li
Subject: [EXT] Re: [PATCH 1/2] fsl-layerscape: add dtb overlay feature
Caution: EXT Email
Hi Sahil,
Am 2021-12-10 07:33, schrieb Sahil Malhotra (OSS):
>> DT nodes can be statically disabled if we know that they are held by
>> HAB and are not released to NS World.
>>
>> OP-TEE does set the status itself via dt_enable_secure_status(),
>> which should present the properly configured FDT when U-Boot takes
over.
> Yes, OP-TEE set the status by dt_enable_secure_status() in DTB overlay
> which gets merged with DTB provided for Linux bootup and then Linux
> boots with merged DTB.
> But u-boot uses the DTB embedded in its image. How can we modify that
> DTB or merge DTB overlay passed by OP-TEE with uboot DTB ?
But then u-boot has the "wrong" dtb. What is the reason, there is an
overlay
instead of a whole dtb? what if the overlay doesn't match the dtb?
"wrong" dtb means that uboot will not be aware of CAAM job ring which
is taken by
OP-TEE and uboot on LS platforms currently use JR0, which is not being
used by any other
entity in LS bootflow.
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.
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.
-michael
