On 01/19/2015 11:24 PM, Thomas Niederprüm wrote: > This patch fixes faulty behaviour in a setup where the input clock for the > SRG is fed through the CLKR/CLKX pin but the McBSP is configured to be > master (SND_SOC_DAIFMT_CBS_CFS). In that case of course CLKR/CLKX must > not be configured as output pin. Otherwise the input clock is messed up > horribly. > > This patch makes it possible to use the CLKR/CLKX pin rather than CLKS to > inject a reference clock in setups where McBSP is master and not both > rx and tx are used. However for this to work it has to be ensured that > set_dai_sysclk() is called after set_dai_fmt(). > > This was tested on a beagleboard-xm using McBSP1 to drive a i2s DAC through > the tx lines (CLKX,FSX,DX). Using this patch the CLKR pin is used to inject > an external reference clock. > > changes since v1: > - added comments explaining the bit masking to disable output on CLKR/CLKX Acked-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> > > Signed-off-by: Thomas Niederprüm <niederp@xxxxxxxxxxxxxxxx> > --- > sound/soc/omap/omap-mcbsp.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c > index bd3ef2a..c37f606 100644 > --- a/sound/soc/omap/omap-mcbsp.c > +++ b/sound/soc/omap/omap-mcbsp.c > @@ -530,8 +530,19 @@ static int omap_mcbsp_dai_set_dai_sysclk(struct snd_soc_dai *cpu_dai, > > case OMAP_MCBSP_SYSCLK_CLKX_EXT: > regs->srgr2 |= CLKSM; > + regs->pcr0 |= SCLKME; > + /* > + * If McBSP is master but yet the CLKX/CLKR pin drives the SRG, > + * disable output on those pins. This enables to inject the > + * reference clock through CLKX/CLKR. For this to work > + * set_dai_sysclk() _needs_ to be called after set_dai_fmt(). > + */ > + regs->pcr0 &= ~CLKXM; > + break; > case OMAP_MCBSP_SYSCLK_CLKR_EXT: > regs->pcr0 |= SCLKME; > + /* Disable ouput on CLKR pin in master mode */ > + regs->pcr0 &= ~CLKRM; > break; > default: > err = -ENODEV; > -- Péter -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
