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Commit 9892dd23 authored by Bob Moore's avatar Bob Moore Committed by Len Brown
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ACPICA: Optimize ACPI register locking 

Removed locking for reads from the ACPI bit registers in PM1
Status, Enable, Control, and PM2 Control. The lock is not required
when reading the single-bit registers. The acpi_get_register_unlocked
function is no longer needed and has been removed. This will
improve performance for reads on these registers.  ACPICA BZ 760.

http://www.acpica.org/bugzilla/show_bug.cgi?id=760



Signed-off-by: default avatarBob Moore <robert.moore@intel.com>
Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent ec41f193

drivers/acpi/acpica/hwsleep.c

+1 −1
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ acpi_status asmlinkage acpi_enter_sleep_state(u8 sleep_state) 
	/* Wait until we enter sleep state */



	do {

		status = acpi_get_register_unlocked(ACPI_BITREG_WAKE_STATUS,

		status = acpi_get_register(ACPI_BITREG_WAKE_STATUS,

						    &in_value);

		if (ACPI_FAILURE(status)) {

			return_ACPI_STATUS(status);

drivers/acpi/acpica/hwxface.c

+27 −38
Original line number Diff line number Diff line
@@ -242,24 +242,35 @@ ACPI_EXPORT_SYMBOL(acpi_write) 


/*******************************************************************************

 *

 * FUNCTION:    acpi_get_register_unlocked

 * FUNCTION:    acpi_get_register

 *

 * PARAMETERS:  register_id     - ID of ACPI bit_register to access

 *              return_value    - Value that was read from the register

 * PARAMETERS:  register_id     - ID of ACPI Bit Register to access

 *              return_value    - Value that was read from the register,

 *                                normalized to bit position zero.

 *

 * RETURN:      Status and the value read from specified Register. Value

 * RETURN:      Status and the value read from the specified Register. Value

 *              returned is normalized to bit0 (is shifted all the way right)

 *

 * DESCRIPTION: ACPI bit_register read function. Does not acquire the HW lock.

 *

 * SUPPORTS:    Bit fields in PM1 Status, PM1 Enable, PM1 Control, and

 *              PM2 Control.

 *

 * Note: The hardware lock is not required when reading the ACPI bit registers

 *       since almost all of them are single bit and it does not matter that

 *       the parent hardware register can be split across two physical

 *       registers. The only multi-bit field is SLP_TYP in the PM1 control

 *       register, but this field does not cross an 8-bit boundary (nor does

 *       it make much sense to actually read this field.)

 *

 ******************************************************************************/

acpi_status acpi_get_register_unlocked(u32 register_id, u32 *return_value)

acpi_status acpi_get_register(u32 register_id, u32 *return_value)

{

	u32 register_value = 0;

	struct acpi_bit_register_info *bit_reg_info;

	acpi_status status;



	ACPI_FUNCTION_TRACE(acpi_get_register_unlocked);

	ACPI_FUNCTION_TRACE(acpi_get_register);



	/* Get the info structure corresponding to the requested ACPI Register */
@@ -268,7 +279,7 @@ acpi_status acpi_get_register_unlocked(u32 register_id, u32 *return_value) 
		return_ACPI_STATUS(AE_BAD_PARAMETER);

	}



	/* Read from the register */

	/* Read the entire parent register */



	status = acpi_hw_register_read(bit_reg_info->parent_register,

				       &register_value);
@@ -291,46 +302,24 @@ acpi_status acpi_get_register_unlocked(u32 register_id, u32 *return_value) 
	return_ACPI_STATUS(status);

}



ACPI_EXPORT_SYMBOL(acpi_get_register_unlocked)



/*******************************************************************************

 *

 * FUNCTION:    acpi_get_register

 *

 * PARAMETERS:  register_id     - ID of ACPI bit_register to access

 *              return_value    - Value that was read from the register

 *

 * RETURN:      Status and the value read from specified Register. Value

 *              returned is normalized to bit0 (is shifted all the way right)

 *

 * DESCRIPTION: ACPI bit_register read function.

 *

 ******************************************************************************/

acpi_status acpi_get_register(u32 register_id, u32 *return_value)

{

	acpi_status status;

	acpi_cpu_flags flags;



	flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);

	status = acpi_get_register_unlocked(register_id, return_value);

	acpi_os_release_lock(acpi_gbl_hardware_lock, flags);



	return (status);

}



ACPI_EXPORT_SYMBOL(acpi_get_register)



/*******************************************************************************

 *

 * FUNCTION:    acpi_set_register

 *

 * PARAMETERS:  register_id     - ID of ACPI bit_register to access

 *              Value           - (only used on write) value to write to the

 *                                Register, NOT pre-normalized to the bit pos

 * PARAMETERS:  register_id     - ID of ACPI Bit Register to access

 *              Value           - Value to write to the register, in bit

 *                                position zero. The bit is automaticallly

 *                                shifted to the correct position.

 *

 * RETURN:      Status

 *

 * DESCRIPTION: ACPI Bit Register write function.

 * DESCRIPTION: ACPI Bit Register write function. Acquires the hardware lock

 *              since most operations require a read/modify/write sequence.

 *

 * SUPPORTS:    Bit fields in PM1 Status, PM1 Enable, PM1 Control, and

 *              PM2 Control.

 *

 ******************************************************************************/

acpi_status acpi_set_register(u32 register_id, u32 value)

drivers/acpi/processor_idle.c

+1 −1
Original line number Diff line number Diff line
@@ -800,7 +800,7 @@ static int acpi_idle_bm_check(void) 
{

	u32 bm_status = 0;



	acpi_get_register_unlocked(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);

	acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);

	if (bm_status)

		acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);

	/*

include/acpi/acpixf.h

+0 −2
Original line number Diff line number Diff line
@@ -347,8 +347,6 @@ acpi_status acpi_reset(void); 


acpi_status acpi_get_register(u32 register_id, u32 * return_value);



acpi_status acpi_get_register_unlocked(u32 register_id, u32 *return_value);



acpi_status acpi_set_register(u32 register_id, u32 value);



acpi_status acpi_set_firmware_waking_vector(u32 physical_address);