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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> |
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| .. | ||
| emif.c | ||
| emif.h | ||
| Kconfig | ||
| Makefile | ||
| of_memory.c | ||
| of_memory.h | ||
| tegra20-mc.c | ||
| tegra30-mc.c | ||