[PATCH v2 0/2] clk: bcm2835: PCM clock improvements
stefan.wahren at i2se.com
Wed May 31 07:58:01 PDT 2017
Am 31.05.2017 um 11:18 schrieb Phil Elwell:
> The switch to using the upstream bcm2835_cprman clock driver caused a
> few problems for users of PCM (I2S) peripherals. Audio applications
> require accurate, stable clocks, and the cprman driver wasn't
> conservative enough in its choice of clock sources.
> These patches restrict the clock sources for the PCM peripheral in two
> ways: the first causes all possible sources except OSC and PLLD_PER
> to be ignored, while the second allows clocks to be specified as
> "low_jitter", causing the effects of fractional divisors to be taken
> into account when comparing potential clocks for accuracy. In practice,
> the combined effect of the two patches is to choose OSC as a source if
> an integer divisor can be used, otherwise PLLD_PER is chosen.
> Changes in v2:
> * Extended bcm2835_pcm_per_parents to cover the pllh_aux slot, and gave
> it a comment in patch 1.
> * Added a REGISTER_PCM_CLK analagous to REGISTER_PER_CLK in patch 1.
> * Renamed temporary variable idiv to int_div in patch 2.
> Phil Elwell (2):
> clk: bcm2835: Limit PCM clock to OSC and PLLD_PER
> clk: bcm2835: Minimise clock jitter for PCM clock
> drivers/clk/bcm/clk-bcm2835.c | 50 ++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 45 insertions(+), 5 deletions(-)
For the whole series:
Acked-by: Stefan Wahren <stefan.wahren at i2se.com>
I hope Eric as the author of the driver has a chance to look over the
More information about the linux-rpi-kernel