public-mirrors/linux
1
0
Fork 0
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-08-04 00:06:36 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

omap: McBSP: Do not enable SRG in slave mode

Browse source 
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 <peter.ujfalusi@nokia.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Peter Ujfalusi 2010-08-31 08:11:44 +00:00 • committed by Tony Lindgren
parent 813f6c5850
commit ce3f054bdd
1 changed files with 8 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
arch/arm/plat-omap/mcbsp.c
View file

@ -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));