[PATCH v2 00/13] mailbox: pcc: Fixes and cleanup/refactoring

Sudeep Holla
2025-03-05T16:38:58Z

Here is a summary of the changes in this patch series:

1. Fix for race condition in updating of the chan_in_use flag

Ensures correct updating of the chan_in_use flag to avoid potential race
conditions.

2. Interrupt handling fix

Ensures platform acknowledgment interrupts are always cleared to avoid
leaving the interrupt asserted forever.

3. Endian conversion cleanup

Removes unnecessary endianness conversion in the PCC mailbox driver.

4. Memory mapping improvements

Uses acpi_os_ioremap() instead of direct mapping methods for better ACPI
compatibility.

5. Return early if the command complete register is absent

Ensures that if no GAS (Generic Address Structure) register is available,
the function exits early.

6. Refactor IRQ handler and move error handling to a separate function

Improves readability of error handling in the PCC mailbox driver’s
interrupt handler.

7. Code restructuring to avoid unnecessary forward declaration

Moves pcc_mbox_ioremap() function to a more appropriate location with
no functional impact.

8. Shared memory mapping refactoring/enhancements

Ensures the shared memory is always mapped and unmapped in the PCC
mailbox driver when the PCC channel is requested and release.

9. Refactored check_and_ack() Function

Simplifies and improves the logic for handling type4 platform notification
acknowledgments.

10-14. Shared memory handling simplifications across multiple drivers

Simplifies shared memory handling in:
Kunpeng HCCS driver (soc: hisilicon)
Apm X-Gene Slimpro I2C driver
X-Gene hardware monitoring driver (hwmon)
ACPI PCC driver
ACPI CPPC driver

The X-gene related changes now change the mapping attributes to align
with ACPI specification. There are possibilities for more cleanups on
top of these changes around how the shmem is accessed within these
driver.

Also, my main aim is to get 1-8 merged first and target 9-13 for
following merge window through respective tree.

Overall, the patch series focuses on improving correctness, efficiency, and
maintainability of the PCC mailbox driver and related components by fixing
race conditions, optimizing memory handling, simplifying shared memory
interactions, and refactoring code for clarity.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
Adam, Robbie, Huisong,

Please test this in your setup as you are the ones reporting/fixing the
issues or last modified the code that I am changing here.

Changes in v2:
- Improved time vs flow graph for the platform ack interrupt
acknowledgment issue in patch 2
- Replaced PCC_ACK_FLAG_MASK with PCC_CMD_COMPLETION_NOTIFY in patch 3
- Fixed return value check from pcc_mbox_error_check_and_clear() in patch 6
- Dropped the change moving the function pcc_mbox_ioremap()
- Adjusted error message in kunpeng_hccs driver after the change
- Added the received ack/review tags
- Link to v1: https://lore.kernel.org/r/20250303-pcc_fixes_updates-v1-0-3b44f3d134b1@arm.com

---
Huisong Li (1):
mailbox: pcc: Fix the possible race in updation of chan_in_use flag

Sudeep Holla (12):
mailbox: pcc: Always clear the platform ack interrupt first
mailbox: pcc: Drop unnecessary endianness conversion of pcc_hdr.flags
mailbox: pcc: Return early if no GAS register from pcc_mbox_cmd_complete_check
mailbox: pcc: Use acpi_os_ioremap() instead of ioremap()
mailbox: pcc: Refactor error handling in irq handler into separate function
mailbox: pcc: Always map the shared memory communication address
mailbox: pcc: Refactor and simplify check_and_ack()
soc: hisilicon: kunpeng_hccs: Simplify PCC shared memory region handling
i2c: xgene-slimpro: Simplify PCC shared memory region handling
hwmon: (xgene-hwmon) Simplify PCC shared memory region handling
ACPI: PCC: Simplify PCC shared memory region handling
ACPI: CPPC: Simplify PCC shared memory region handling

drivers/acpi/acpi_pcc.c | 13 +---
drivers/acpi/cppc_acpi.c | 16 +----
drivers/hwmon/xgene-hwmon.c | 40 ++----------
drivers/i2c/busses/i2c-xgene-slimpro.c | 39 ++----------
drivers/mailbox/pcc.c | 112 ++++++++++++++++-----------------
drivers/soc/hisilicon/kunpeng_hccs.c | 42 +++++--------
drivers/soc/hisilicon/kunpeng_hccs.h | 2 -
include/acpi/pcc.h | 6 --
8 files changed, 83 insertions(+), 187 deletions(-)
---
base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6
change-id: 20250303-pcc_fixes_updates-55a17fd28e76

Best regards,
--
Regards,
Sudeep