From ce3f054bdd4e022fa0ee9d11a215ec32f1caa12d Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Tue, 31 Aug 2010 08:11:44 +0000 Subject: [PATCH] omap: McBSP: Do not enable SRG in slave mode McBSP SRG (Sample Rate Generator) and FSG (Frame Sync Generator) is only needed to be enabled, when McBSP is master. In McBSP slave mode, the SRG, and FSG can be kept disabled, which might save some power at the end in this configuration. Signed-off-by: Peter Ujfalusi Acked-by: Jarkko Nikula Signed-off-by: Tony Lindgren --- arch/arm/plat-omap/mcbsp.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c index e31496e35b0f..ecbfe398a309 100644 --- a/arch/arm/plat-omap/mcbsp.c +++ b/arch/arm/plat-omap/mcbsp.c @@ -878,7 +878,7 @@ EXPORT_SYMBOL(omap_mcbsp_free); void omap_mcbsp_start(unsigned int id, int tx, int rx) { struct omap_mcbsp *mcbsp; - int idle; + int enable_srg = 0; u16 w; if (!omap_mcbsp_check_valid_id(id)) { @@ -893,10 +893,13 @@ void omap_mcbsp_start(unsigned int id, int tx, int rx) mcbsp->rx_word_length = (MCBSP_READ_CACHE(mcbsp, RCR1) >> 5) & 0x7; mcbsp->tx_word_length = (MCBSP_READ_CACHE(mcbsp, XCR1) >> 5) & 0x7; - idle = !((MCBSP_READ_CACHE(mcbsp, SPCR2) | - MCBSP_READ_CACHE(mcbsp, SPCR1)) & 1); + /* Only enable SRG, if McBSP is master */ + w = MCBSP_READ_CACHE(mcbsp, PCR0); + if (w & (FSXM | FSRM | CLKXM | CLKRM)) + enable_srg = !((MCBSP_READ_CACHE(mcbsp, SPCR2) | + MCBSP_READ_CACHE(mcbsp, SPCR1)) & 1); - if (idle) { + if (enable_srg) { /* Start the sample generator */ w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w | (1 << 6)); @@ -919,7 +922,7 @@ void omap_mcbsp_start(unsigned int id, int tx, int rx) */ udelay(500); - if (idle) { + if (enable_srg) { /* Start frame sync */ w = MCBSP_READ_CACHE(mcbsp, SPCR2); MCBSP_WRITE(mcbsp, SPCR2, w | (1 << 7)); -- 2.39.5