On Thu, Jun 29, 2023 at 3:16 AM Mukesh Ojha [off-list ref] wrote:

On 6/29/2023 4:27 AM, Rob Herring wrote:

quoted

On Wed, Jun 28, 2023 at 6:37 AM Mukesh Ojha [off-list ref] wrote:

quoted

This driver was inspired from the fact pstore ram region should be
fixed and boot firmware need to have awarness about this region,
so that it will be persistent across boot. But, there are many
QCOM SoC which does not support warm boot from hardware but they
have minidump support from the software, and for them, there is
no need of this pstore ram region to be fixed, but at the same
time have interest in the pstore frontends data. So, this driver
get the dynamic reserved region from the ram and register the
ramoops platform device.

  +---------+     +---------+   +--------+     +---------+
  | console |     | pmsg    |   | ftrace |     | dmesg   |
  +---------+     +---------+   +--------+     +---------+
        |             |             |              |
        |             |             |              |
        +------------------------------------------+
                           |
                          \ /
                   +----------------+
             (1)   |pstore frontends|
                   +----------------+
                           |
                          \ /
                  +------------------- +
             (2)  | pstore backend(ram)|
                  +--------------------+
                           |
                          \ /
                  +--------------------+
             (3)  |qcom_pstore_minidump|
                  +--------------------+
                           |
                          \ /
                    +---------------+
             (4)    | qcom_minidump |
                    +---------------+

This driver will route all the pstore front data to the stored
in qcom pstore reserved region and the reason of showing an
arrow from (3) to (4) as qcom_pstore_minidump driver will register
all the available frontends region with qcom minidump driver
in upcoming patch.

Signed-off-by: Mukesh Ojha <redacted>
---
  drivers/soc/qcom/Kconfig                | 12 +++++
  drivers/soc/qcom/Makefile               |  1 +
  drivers/soc/qcom/qcom_pstore_minidump.c | 85 +++++++++++++++++++++++++++++++++

drivers/soc/ is the dumping ground for things with no other place. As
this is a pstore driver, it belongs with pstore.

The inspiration of this driver was taken from
drivers/platform/chrome/chromeos_pstore.c, do you think that is misplaced ?

The difference is really that's nothing more than platform specific
logic to instantiate a normal ramoops device. It's kind of ugly, yes,
but it's still just a normal ramoops device in the end. Your case is
that plus all the extra parts for minidump.

Rob

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