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Commit 8af4baa7 authored by Thomas Niederprüm's avatar Thomas Niederprüm Committed by Mark Brown
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ASoC: OMAP: mcbsp: Fix CLKX and CLKR pinmux when used as inputs 



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.

Signed-off-by: default avatarThomas Niederprüm <niederp@physik.uni-kl.de>
Acked-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent fb5ab729

sound/soc/omap/omap-mcbsp.c

+11 −0
Original line number Diff line number Diff line
@@ -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;