On Fri, Jun 24, 2022 at 6:52 AM Francesco Dolcini <francesco.dolc...@toradex.com> wrote: > > Set CLK01 and CLK02 to 24MHz and enable it in CCM_CCOSR register. > > This clock is used by both the audio codec (CLKO1) and by the CSI camera > (CLKO2) and is expected to be 24MHz. > > Despite the wrong 16.5MHz there was no real issue because of the wrong > frequency since Linux reconfigures the clocks afterward, however this > was triggering an issue with noise coming from the SGTL5000 audio codec. > > The problem is that the SGTL5000 does not have a reset pin and after it > is configured if the input MCLK clock is disabled it produces a constant > noise on its output, this was happening on software reboot. > > Forcing the clock to be enabled in U-Boot prevent the problem by making > sure that the clock is always available, without this change as soon as > Linux was changing the clock tree (setting clk_out_sel=1 without setting > clko2_en=1) the noise would start till the actual clock was enabled > (clko2_en=1) during the SGTL5000 driver probe. > > Signed-off-by: Francesco Dolcini <francesco.dolc...@toradex.com>
Reviewed-by: Fabio Estevam <feste...@denx.de>