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Commit 19db62ea authored by Misael Lopez Cruz's avatar Misael Lopez Cruz Committed by Mark Brown
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ASoC: davinci-mcasp: Logic low for inactive output slots 



The default state when serializers are in inactive slots is Hi-Z.
In some cases, there are no additional components driving the data
lines to a safe state so they might have noise.

While in inactive slots, the McASP AXR pins configured as outputs
can be driven low through the serializer pin drive mode setting
(DISMOD) to prevent such noise.

Signed-off-by: default avatarMisael Lopez Cruz <misael.lopez@ti.com>
Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 518f6bab

sound/soc/davinci/davinci-mcasp.c

+2 −0
Original line number Diff line number Diff line
@@ -686,6 +686,8 @@ static int mcasp_common_hw_param(struct davinci_mcasp *mcasp, int stream, 
		if (mcasp->serial_dir[i] == TX_MODE &&

					tx_ser < max_active_serializers) {

			mcasp_set_bits(mcasp, DAVINCI_MCASP_PDIR_REG, AXR(i));

			mcasp_mod_bits(mcasp, DAVINCI_MCASP_XRSRCTL_REG(i),

				       DISMOD_LOW, DISMOD_MASK);

			tx_ser++;

		} else if (mcasp->serial_dir[i] == RX_MODE &&

					rx_ser < max_active_serializers) {

sound/soc/davinci/davinci-mcasp.h

+4 −1
Original line number Diff line number Diff line
@@ -215,7 +215,10 @@ 
 * DAVINCI_MCASP_XRSRCTL_BASE_REG -  Serializer Control Register Bits

 */

#define MODE(val)	(val)

#define DISMOD		(val)(val<<2)

#define DISMOD_3STATE	(0x0)

#define DISMOD_LOW	(0x2 << 2)

#define DISMOD_HIGH	(0x3 << 2)

#define DISMOD_MASK	DISMOD_HIGH

#define TXSTATE		BIT(4)

#define RXSTATE		BIT(5)

#define SRMOD_MASK	3