Re: [PATCH 2/2] ACPI / PMIC: XPower: optimize MIPI PMIQ sequence I2C-bus accesses
From: Andy Shevchenko <hidden>
Date: 2021-07-02 16:59:15
On Fri, Jul 2, 2021 at 7:51 PM Hans de Goede [off-list ref] wrote:
The I2C-bus to the XPower AXP288 is shared between the Linux kernel and the SoCs PUNIT. The PUNIT has a semaphore which the kernel must "lock" before it may use the bus and while the kernel holds the semaphore the CPU and GPU power-states must not be changed otherwise the system will freeze. This is a complex process, which is quite expensive. This is all done by iosf_mbi_block_punit_i2c_access(). To ensure that no unguarded I2C-bus accesses happen, iosf_mbi_block_punit_i2c_access() gets called by the I2C-bus-driver for every I2C transfer. Because this is so expensive it is allowed to call iosf_mbi_block_punit_i2c_access() in a nested fashion, so that higher-level code which does multiple I2C-transfers can call it once for a group of transfers, turning the calls done by the I2C-bus-driver into no-ops. The default exec_mipi_pmic_seq_element implementation from drivers/acpi/pmic/intel_pmic.c does a regmap_update_bits() call and the involved registers are typically marked as volatile in the regmap, so this leads to 2 I2C-bus accesses. Add a XPower AXP288 specific implementation of exec_mipi_pmic_seq_element which calls iosf_mbi_block_punit_i2c_access() calls before the regmap_update_bits() call to avoid having to do the whole expensive acquire PUNIT semaphore dance twice.
Same as per patch 1. Reviewed-by: Andy Shevchenko <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Hans de Goede <redacted> --- drivers/acpi/pmic/intel_pmic_xpower.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)diff --git a/drivers/acpi/pmic/intel_pmic_xpower.c b/drivers/acpi/pmic/intel_pmic_xpower.c index 644a495a4f13..93c516ad361e 100644 --- a/drivers/acpi/pmic/intel_pmic_xpower.c +++ b/drivers/acpi/pmic/intel_pmic_xpower.c@@ -266,10 +266,34 @@ static int intel_xpower_pmic_get_raw_temp(struct regmap *regmap, int reg) return ret; } +static int intel_xpower_exec_mipi_pmic_seq_element(struct regmap *regmap, + u16 i2c_address, u32 reg_address, + u32 value, u32 mask) +{ + int ret; + + if (i2c_address != 0x34) { + pr_err("%s: Unexpected i2c-addr: 0x%02x (reg-addr 0x%x value 0x%x mask 0x%x)\n", + __func__, i2c_address, reg_address, value, mask); + return -ENXIO; + } + + ret = iosf_mbi_block_punit_i2c_access(); + if (ret) + return ret; + + ret = regmap_update_bits(regmap, reg_address, mask, value); + + iosf_mbi_unblock_punit_i2c_access(); + + return ret; +} + static struct intel_pmic_opregion_data intel_xpower_pmic_opregion_data = { .get_power = intel_xpower_pmic_get_power, .update_power = intel_xpower_pmic_update_power, .get_raw_temp = intel_xpower_pmic_get_raw_temp, + .exec_mipi_pmic_seq_element = intel_xpower_exec_mipi_pmic_seq_element, .power_table = power_table, .power_table_count = ARRAY_SIZE(power_table), .thermal_table = thermal_table, --2.31.1
-- With Best Regards, Andy Shevchenko