From: grinberg@compulab•co.il (Igor Grinberg)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/3] ALSA: pxa27x: fix ac97 cold reset
Date: Tue, 08 Jan 2013 10:17:59 +0200 [thread overview]
Message-ID: <50EBD637.8020602@compulab.co.il> (raw)
In-Reply-To: <1357595714-13698-2-git-send-email-mikedunn@newsguy.com>
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@newsguy•com>
Acked-by: Igor Grinberg <grinberg@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.
next prev parent reply other threads:[~2013-01-08 8:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-07 21:55 [PATCH 0/3] ALSA: pxa27x: ac97 reset fixes Mike Dunn
2013-01-07 21:55 ` [PATCH 1/3] ALSA: pxa27x: fix ac97 cold reset Mike Dunn
2013-01-08 8:17 ` Igor Grinberg [this message]
2013-01-07 21:55 ` [PATCH 2/3] ALSA: pxa27x: fix ac97 warm reset Mike Dunn
2013-01-08 8:36 ` Igor Grinberg
2013-01-07 21:55 ` [PATCH 3/3] ALSA: pxa27x: rename pxa27x_assert_ac97reset() Mike Dunn
2013-01-08 8:36 ` Igor Grinberg
2013-01-08 8:44 ` [PATCH 0/3] ALSA: pxa27x: ac97 reset fixes Igor Grinberg
2013-01-08 11:30 ` Mark Brown
2013-01-08 19:16 ` Robert Jarzmik
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