Program the SDRC_MR_0 register as well during SDRC clock changes.
This register allows selection of the memory CAS latency. Some SDRAM
chips, such as the Qimonda HYB18M512160AF6, have a lower CAS latency
at lower clock rates.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
When changing the SDRAM clock from 166MHz to 83MHz via the CORE DPLL M2
divider, add a short delay before returning to SDRAM to allow the SDRC
time to stabilize. Without this delay, the system is prone to random
panics upon re-entering SDRAM.
This time delay varies based on MPU frequency. At 500MHz MPU frequency at
room temperature, 64 loops seems to work okay; so add another 32 loops for
environmental and process variation.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
The original CDP kernel that this code comes from waited for 0x800
loops after switching the CORE DPLL M2 divider. This does not appear
to be necessary.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
According to the 34xx TRM Rev. K section 11.2.4.4.11.1 "Purpose of the
DLL/CDL Module," the SDRC delay-locked-loop can be locked at any SDRC
clock frequency from 83MHz to 166MHz. CDP code unconditionally
unlocked the DLL whenever shifting to a lower SDRC speed, but this
seems unnecessary and error-prone, as the DLL is no longer able to
compensate for process, voltage, and temperature variations. Instead,
only unlock the DLL when the SDRC clock rate would be less than 83MHz.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Renumber registers in omap3_sram_configure_core_dpll() assembly code to
make space for additional parameters.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Clear the SDRC_POWER.PWRENA bit before putting the SDRAM into self-refresh
mode. This prevents the SDRC from attempting to power off the SDRAM,
which can cause the system to hang.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Add more barriers in the SRAM CORE DPLL M2 divider change code.
- Add a DSB SY after the function's entry point to flush all cached
and buffered writes and wait for the interconnect to claim that they
have completed[1]. The idea here is to force all delayed write
traffic going to the SDRAM to at least post to the L3 interconnect
before continuing. If these writes are allowed to occur after the
SDRC is idled, the writes will not be acknowledged and the ARM will
stall.
Note that in this case, it does not matter if the writes actually
complete to the SDRAM - it is only necessary for the writes to leave
the ARM itself. If the writes are posted by the interconnect when
the SDRC goes into idle, the writes will be delayed until the SDRC
returns from idle[2]. If the SDRC is in the middle of a write when
it is requested to enter idle, the SDRC will not acknowledge the
idle request until the writes complete to the SDRAM.[3]
The old-style DMB in sdram_in_selfrefresh is now superfluous, so,
remove it.
- Add an ISB before the function's exit point to prevent the ARM from
speculatively executing into SDRAM before the SDRAM is enabled[4].
...
1. ARMv7 ARM (DDI 0406A) A3-47, A3-48.
2. Private communication with Richard Woodruff <r-woodruff2@ti.com>.
3. Private communication with Richard Woodruff <r-woodruff2@ti.com>.
4. ARMv7 ARM (DDI 0406A) A3-48.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Add minimal omap3430 support based on earlier patches from
Syed Mohammed Khasim. Also merge in omap34xx SRAM support
from Karthik Dasu and use consistent naming for sram init
functions.
Also do following changes that make 34xx support usable:
- Remove unused sram.c functions for 34xx
- Rename IRQ_SIR_IRQ to INTCPS_SIR_IRQ and define it locally
in entry-macro.S
- Update mach-omap2/io.c to support 2420, 2430, and 34xx
- Also merge in 34xx GPMC changes to add fields wr_access and
wr_data_mux_bus from Adrian Hunter
- Remove memory initialization call omap2_init_memory() until
until more generic memory initialization patches are posted.
It's OK to rely on bootloader initialization until then.
Signed-off-by: Syed Mohammed, Khasim <khasim@ti.com>
Signed-off-by: Karthik Dasu<karthik-dp@ti.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Paul Walmsley