Hi Sahil,
Am 2021-12-23 09:46, schrieb Sahil Malhotra (OSS):
-----Original Message----- From: U-Boot u-boot-bounces@lists.denx.de On Behalf Of Michael Walle Sent: Monday, December 20, 2021 6:23 PM 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: [EXT] Re: [PATCH 1/2] fsl-layerscape: add dtb overlay feature
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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