From: Wolfram Sang <w.sang@pengutronix•de>
To: Eric Millbrandt <emillbrandt@dekaresearch•com>
Cc: linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH] powerpc/5200: tighten up ac97 reset timing
Date: Fri, 3 Sep 2010 18:02:09 +0200 [thread overview]
Message-ID: <20100903160209.GE4813@pengutronix.de> (raw)
In-Reply-To: <1283528722-15644-1-git-send-email-emillbrandt@dekaresearch.com>
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On Fri, Sep 03, 2010 at 11:45:22AM -0400, Eric Millbrandt wrote:
> Tighten up time timing around the gpio reset functionality. Add a 200ns
> delay before remuxing the pins back to ac97 to comply with the ac97 spec.
> This delay ensures that sync and sdata_out are held low while reset
> transitions to high.
>
> Signed-off-by: Eric Millbrandt <emillbrandt@dekaresearch•com>
> ---
>
> Scope shots are availible upon request.
>
> arch/powerpc/platforms/52xx/mpc52xx_common.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/platforms/52xx/mpc52xx_common.c
> index 6e90531..79adfe7 100644
> --- a/arch/powerpc/platforms/52xx/mpc52xx_common.c
> +++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c
> @@ -326,11 +326,14 @@ int mpc5200_psc_ac97_gpio_reset(int psc_number)
> clrbits8(&wkup_gpio->wkup_dvo, reset);
>
> /* wait at lease 1 us */
Maybe you could fix this typo as well while you are here?
> - udelay(2);
> + udelay(1);
>
> /* Deassert reset */
> setbits8(&wkup_gpio->wkup_dvo, reset);
>
> + /* wait at least 200ns */
> + __delay(7);
ndelay(200)?
> +
> /* Restore pin-muxing */
> out_be32(&simple_gpio->port_config, mux);
>
> --
> 1.6.3.1
>
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--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next prev parent reply other threads:[~2010-09-03 16:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-03 15:45 [PATCH] powerpc/5200: tighten up ac97 reset timing Eric Millbrandt
2010-09-03 16:02 ` Wolfram Sang [this message]
2010-09-03 16:17 ` Eric Millbrandt
2010-09-03 16:22 ` Wolfram Sang
2010-09-03 16:40 ` Eric Millbrandt
2010-09-03 16:49 ` Wolfram Sang
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