On Meson8b the MPLL parent clock (fixed_pll) has a rate of 2550MHz.
Multiplying this with SDM_DEN results in a value greater than 32bits.
This is not a problem on the 64bit Meson GX SoCs, but it may result in
undefined behavior on the older 32bit Meson8b SoC.
While rate_from_params was only introduced recently to make the math
reusable from _round_rate and _recalc_rate the original bug exists much
longer.
Fixes: 1c50da4f27 ("clk: meson: add mpll support")
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
[as discussed on the ml, use DIV_ROUND_UP_ULL]
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
According to the public datasheet all register bits in HHI_MPLL_CNTL7,
HHI_MPLL_CNTL8 and HHI_MPLL_CNTL9 default to zero. On all GX SoCs these
seem to be initialized by the bootloader to some default value.
However, on my Meson8 board they are not initialized, leading to a
division by zero in rate_from_params as the math is:
(parent_rate * SDM_DEN) / ((SDM_DEN * 0) + 0)
According to the datasheet, the minimum n2 value is 4. The rate provided
by the clock when n2 is less than this minimum is unpredictable. In such
case, we report an error.
Although the rate_from_params function was only introduced recently the
original bug has been there for much longer. It was only exposed
recently when the MPLL clocks were added to the Meson8b clock driver.
Fixes: 1c50da4f27 ("clk: meson: add mpll support")
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Gxbb datasheet says N2 maximum value is 127 but the register field is
9 bits wide, the maximum value should 511.
Test shows value greater than 127, all the way to 511, works well
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/20170309104154.28295-9-jbrunet@baylibre.com
This patch adds new callbacks to the meson-mpll driver to control
and set the pll rate. For this, we also need to add the enable bit and
sdm enable bit. The corresponding parameters are added to mpll data
structure.
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/20170309104154.28295-6-jbrunet@baylibre.com
MPLLs are adjustable rate clocks derived from PLLs. On both Meson8b and
GXBB they appear to be only derived from fixed_pll.
Add support for these clock types so that they can be added to their
respective drivers.
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Martin Blumenstingl
Jerome Brunet
Michael Turquette