kernel_optimize_test/drivers/memory
Grygorii Strashko f02503b2ff memory: emif: errata i743: Prohibit usage of Power-Down mode
ERRATA DESCRIPTION :
The EMIF supports power-down state for low power. The EMIF
automatically puts the SDRAM into power-down after the memory is
not accessed for a defined number of cycles and the
EMIF_PWR_MGMT_CTRL[10:8] REG_LP_MODE bit field is set to 0x4.
As the EMIF supports automatic output impedance calibration, a ZQ
calibration long command is issued every time it exits active
power-down and precharge power-down modes. The EMIF waits and
blocks any other command during this calibration.
The EMIF does not allow selective disabling of ZQ calibration upon
exit of power-down mode. Due to very short periods of power-down
cycles, ZQ calibration overhead creates bandwidth issues and
increases overall system power consumption. On the other hand,
issuing ZQ calibration long commands when exiting self-refresh is
still required.

WORKAROUND :
Because there is no power consumption benefit of the power-down due
to the calibration and there is a performance risk, the guideline
is to not allow power-down state and, therefore, to not have set
the EMIF_PWR_MGMT_CTRL[10:8] REG_LP_MODE bit field to 0x4.

This is applicable only for EMIF4D IP used in OMAP4 Soc's.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Vitaly Chernooky <vitaly.chernooky@ti.com>
Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25 13:18:13 -07:00
..
emif.c memory: emif: errata i743: Prohibit usage of Power-Down mode 2013-03-25 13:18:13 -07:00
emif.h memory: emif: handle frequency and voltage change events 2012-05-02 10:52:09 -07:00
Kconfig ARM: tegra30: Make MC optional in Kconfig 2012-05-11 15:22:56 -07:00
Makefile memory: fix build when CONFIG_OF && !CONFIG_DDR 2012-09-05 11:57:19 -07:00
of_memory.c memory: emif: add device tree support to emif driver 2012-09-04 16:14:31 -07:00
of_memory.h memory: fix build when CONFIG_OF && !CONFIG_DDR 2012-09-05 11:57:19 -07:00
tegra20-mc.c memory: Convert to devm_ioremap_resource() 2013-01-22 11:41:56 -08:00
tegra30-mc.c memory: tegra30: Fix build error w/o PM 2013-03-15 11:10:49 -07:00