Nothing apart from only being used by arm64 platforms today, which is
circumstantial.
I understand you need to find a place to add the:
acpi_indirect_io_scan_init()
to be called from core ACPI code because ACPI can't handle probe
dependencies in any other way but other than that this patch is
a Hisilicon ACPI driver - there is nothing generic in it (or at
least there are no standard bindings to make it so).
Whether a callback from ACPI core code (acpi_scan_init()) to a driver
specific hook is sane or not that's the question and the only reason
why you want to add this in drivers/acpi/arm64 rather than, say,
drivers/bus (as you do for the DT driver).
I do not know Rafael's opinion on the above, I would like to help
you make forward progress but please understand my concerns, mostly
on FW side.
I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but
no response to this specific note so I kept on the same path.
Here's what I then wrote:
"I think another solution - which you may prefer - is to avoid adding
this scan handler (and all this other scan code) and add a check like
acpi_is_serial_bus_slave() [which checks the device parent versus a list
of known indirectIO hosts] to not enumerate these children, and do it
from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"
Hi Rafael, Lorenzo,
I can avoid adding the scan handler in acpi_indirectio.c by skipping the
child enumeration, like with this change in scan.c:
+static const struct acpi_device_id indirect_io_hosts[] = {
+ {"HISI0191", 0}, /* HiSilicon LPC host */
+ {},
+};
+
+static bool acpi_is_indirect_io_slave(struct acpi_device *device)
+{
+ struct acpi_device *parent = dev->parent;
+
+ if (!parent || acpi_match_device_ids(parent, indirect_io_hosts))
+ return false;
+
+ return true;
+}
+
static bool acpi_is_serial_bus_slave(struct acpi_device *device)
{
struct list_head resource_list;
bool is_serial_bus_slave = false;
+ if (acpi_is_indirect_io_slave(device))
+ return true;
+
/* Macs use device properties in lieu of _CRS resources */
This means I can move all this scan code into the LLDD.
What do you think? Please let me know.
John
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