[ 026/128] ALSA: pxa27x: fix ac97 cold reset

Ben Hutchings
2013-02-03T14:55:25Z

From: Mike Dunn <mikedunn@newsguy.com>

commit 41b645c8624df6ace020a8863ad1449d69140f7d upstream.

Cold reset on the pxa27x currently fails and

pxa2xx_ac97_try_cold_reset: cold reset timeout (GSR=0x44)

appears in the kernel log. Through trial-and-error (the pxa270 developer's
manual is mostly incoherent on the topic of ac97 reset), I got cold reset to
complete by setting the WARM_RST bit in the GCR register (and later noticed that
pxa3xx does this for cold reset as well). Also, a timeout loop is needed to
wait for the reset to complete.

Tested on a palm treo 680 machine.

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
sound/arm/pxa2xx-ac97-lib.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/arm/pxa2xx-ac97-lib.c b/sound/arm/pxa2xx-ac97-lib.c
index 6fc0ae9..1ecd0a66 100644
--- a/sound/arm/pxa2xx-ac97-lib.c
+++ b/sound/arm/pxa2xx-ac97-lib.c
@@ -148,6 +148,8 @@ static inline void pxa_ac97_warm_pxa27x(void)

static inline void pxa_ac97_cold_pxa27x(void)
{
+ unsigned int timeout;
+
GCR &= GCR_COLD_RST; /* clear everything but nCRST */
GCR &= ~GCR_COLD_RST; /* then assert nCRST */

@@ -157,8 +159,10 @@ static inline void pxa_ac97_cold_pxa27x(void)
clk_enable(ac97conf_clk);
udelay(5);
clk_disable(ac97conf_clk);
- GCR = GCR_COLD_RST;
- udelay(50);
+ GCR = GCR_COLD_RST | GCR_WARM_RST;
+ timeout = 100; /* wait for the codec-ready bit to be set */
+ while (!((GSR | gsr_bits) & (GSR_PCR | GSR_SCR)) && timeout--)
+ mdelay(1);
}
#endif