[PATCH 1/3] ALSA: pxa27x: fix ac97 cold reset

[Igor Grinberg]

On 01/07/13 23:55, Mike Dunn wrote:
> 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 at newsguy.com>

Acked-by: Igor Grinberg <grinberg at compulab.co.il>

> ---
>  sound/arm/pxa2xx-ac97-lib.c |    8 ++++++--
>  1 files 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
>  

-- 
Regards,
Igor.