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ACPI / PMIC: XPower: optimize MIPI PMIQ sequence I2C-bus accesses

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The I2C-bus to the XPower AXP288 is shared between the Linux kernel and
the SoCs P-Unit. The P-Unit 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 P-Unit semaphore dance twice.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans de Goede 2021-07-06 18:09:23 +02:00 committed by Rafael J. Wysocki
parent e38ba404f2
commit fd080a01ec
1 changed files with 24 additions and 0 deletions
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24
drivers/acpi/pmic/intel_pmic_xpower.c
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@ -270,10 +270,34 @@ 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,