U-Boot on Tegra30 currently selects a main CPU frequency that cannot be
supported at all on some SKUs, and needs higher VDD_CPU/VDD_CORE values
on some others. This can result in unreliable operation of the main CPUs.
Resolve this by switching to a CPU frequency that can be supported by any
SKU. According to the following link, the maximum supported CPU frequency
of the slowest Tegra30 SKU is 600MHz:
repo http://nv-tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=summary
branch l4t/l4t-r16-r2
path arch/arm/mach-tegra/tegra3_dvfs.c
table cpu_dvfs_table[]
According to that same table, the minimum VDD_CPU required to operate at
that frequency across all SKUs is 1.007V. Given the adjustment resolution
of the TPS65911 PMIC that's used on all Tegra30-based boards we support,
we'll end up using 1.0125V instead.
At that VDD_CPU, tegra3_get_core_floor_mv() in that same file dictates
that VDD_CORE must be at least 1.2V on all SKUs. According to
tegra_core_speedo_mv() (in tegra3_speedo.c in the same source tree),
that voltage is safe for all SKUs.
An alternative would be to port much of the code from tegra3_dvfs.c and
tegra3_speedo.c in the kernel tree mentioned above. That's more work
than I want to take on right now.
While all the currently supported boards use the same regulator chip for
VDD_CPU, different types of regulators are used for VDD_CORE. Hence, we
add some small conditional code to select how VDD_CORE is programmed. If
this becomes more complex in the future as new boards are added, or we
end up adding code to detect the SoC SKU and dynamically determine the
allowed frequency and required voltages, we should probably make this a
runtime call into a function provided by the board file and/or relevant
PMIC driver.
Cc: Alban Bedel <alban.bedel@avionic-design.de>
Cc: Marcel Ziswiler <marcel@ziswiler.com>
Cc: Bard Liao <bardliao@realtek.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
The register writes performed by arch/arm/cpu/arm720t/tegra30/cpu.c
enable_cpu_power_rail() set the voltage to 1.0V not 1.4V as the comment
implies. Fix the comment.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
Based on the Tegra TRM, the system clock (which is the AVP clock) can
run up to 275MHz. On power on, the default sytem clock source is set to
PLLP_OUT0. In function clock_early_init(), PLLP_OUT0 will be set to
408MHz which is beyond system clock's upper limit.
The fix is to set the system clock to CLK_M before initializing PLLP,
and then switch back to PLLP_OUT4, which has an appropriate divider
configured, after PLLP has been configured
Implement this logic in new function tegra30_set_up_pllp(),
which sets up PLLP and all PLLP_OUT* dividers, and handles the AVP
clock switching. Remove the duplicate PLLP setup from pllx_set_rate()
and adjust_pllp_out_freqs().
Signed-off-by: Jimmy Zhang <jimmzhang@nvidia.com>
[swarren, significantly refactored the change]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
A comparison of registers between our internal NV U-Boot and
u-boot-tegra/next showed some discrepancies in the MSELECT
clock divisor programming. T20 doesn't have a MSELECT clk src reg.
Signed-off-by: Tom Warren <twarren@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
This provides SPL support for T30 boards - AVP early init, plus
CPU (A9) init/jump to main U-Boot.
Some changes were made to Tegra20 cpu.c to move common routines
into tegra-common/cpu.c and reduce code duplication.
Signed-off-by: Tom Warren <twarren@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
