On 9/1/2023 12:52 PM, Krzysztof Kozlowski wrote:
On 01/09/2023 08:02, Naman Jain wrote:
Add documentation to describe device tree bindings for QCOM's
platform-parts-info node. Firmware populates these nodes to pass the
information to kernel regarding the subset of hardware blocks
and features like Camera, Modem, Display present in a product.
This is to support that the same software image runs seamlessly on
different platforms where one or more HW blocks are not supported or
if some sub parts for a particular block are not supported.
Purpose of these definitions is to allow clients to know about this,
and thus, handle these cases gracefully.
Whether camera is or is not supported, is defined by presence of camera
node or by its status field.
Existing firmware (e.g. U-Boot) is also doing this - patching DTS when
needed.
I do not think introducing some parallel way makes any sense, so no,
that's not the way to do it.
Best regards,
Krzysztof
Thanks Krzysztof for reviewing the patch. I think for telling whether
the Camera HW block is not
supported / not present, firmware can either remove the device tree
node, or change its status
to disabled, so that is fine.
With this patch, I was trying to address the use case, where Camera is
supported but certain features
of that particular Camera are not supported, due to dependent HW blocks
not present, or due to
product decision to not support it. We wanted to avoid the firmware to
have this overhead of knowing
what these individual bits mean and thus, disable few of the HW blocks
that are supposed to be
disabled. And this is applicable for each of these HW blocks.
For example, we can know from 32 bits provided for modem, if 3G/4G/5G is
supported or not on a
platform. That is decided based on presence/absence of certain HW
blocks, but it may or may not be as
simple as disabling a particular DT node.
Basically we wanted to defer it to the subsystem drivers, to do whatever
they like with this
information on sub-parts that are available.
Will rephrase my commit message to make it clearer, but would like to
hear your thoughts on this first.
Thanks,
Naman Jain
