On 13/07/18 10:58, Jon Hunter wrote:
On 13/07/18 10:41, Ben Dooks wrote:
On 12/07/18 16:56, Stephen Warren wrote:
On 07/12/2018 07:36 AM, Ben Dooks wrote:
Hello, we are looking at up-streaming some of the work we have
done on the tegra2 and tegra3 automotive devices. The automotive
grade devices are close the commercial parts so we would like to
discuss the core changes before submitting.
The changes are mostly with things like the clock setup and a
few peripheral quirks (IIRC these are mostly MMC).
We are proposing to change the device-tree properties for the root
node and any other affected devices from "nvidia,tegraXX" to a new
"nvidia,tegraXXa". We would welcome discussion on whether to update
all the devices at the start
An example of tegra30a.dtsi:
#include "tegra30.dtsi"
/ {
compatible = "nvidia,tegra30a";
clock@60006000 {
compatible = "nvidia,tegra30a-car";
};
}
This doesn't sound right. Auto and commercial parts are identical AFAIK; it's just qualification differences. Hence at most you'd add an extra compatible value and not remove the old one. Better might be to detect this at run-time from the fuses. I think we already do some of that already; search for speedo related code in arch/arm/mach-tegra/.
The nvidia pdk for the automotive didn't set the clocks up in the
same way and we where told that there are certain clock restrictions
for the automotive parts that the commercial ones do not have. Some of
this came from internal discussions with nvidia and NDA'd datasheets
so I don't know how much actual data I can share.
To get the 4.4 kernel to be similar enough to work with the tegra30a
we had to do some changes to the clock initialisation. For things
like the clock I am not sure if leaving a tegra30-car in there would
be a good idea, it may boot but probably won't be stable.
For the fuses, is the fuse driver up early enough to allow the clock
driver could use this? otherwise I think the device-tree change would
be the only way. I'm not sure if I have the information to hand on
how to differentiate the tegra30 and tegra20.
It should be, if you see drivers/soc/tegra/fuse/fuse-tegra.c there is an
'early_initcall(tegra_init_fuse)' and there is a 'tegra_fuse_read_early()'
function that can be used.
Ok, I've tried looking through all the data-sheets I have and I can't
find any data on which fuse-bits would be needed to identify the two
versions. Does anyone else know where to look?
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
https://www.codethink.co.uk/privacy.html
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