[PATCH v2] powerpc/5200: tighten up ac97 reset timing
grant.likely at secretlab.ca
Thu Sep 9 03:55:36 EST 2010
On Fri, Sep 03, 2010 at 01:27:38PM -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.
> Signed-off-by: Eric Millbrandt <emillbrandt at dekaresearch.com>
> Scope shots availible upon request
> changes since v1
> - amended with comments from Wolfram Sang
> arch/powerpc/platforms/52xx/mpc52xx_common.c | 8 ++++++--
> 1 files changed, 6 insertions(+), 2 deletions(-)
Applied, but the patch was mangled (tabs->spaces) and I had to fix it
up by hand. You'll need to find a way to get out from under your
corporate email manging server.
> diff --git a/arch/powerpc/platforms/52xx/mpc52xx_common.c b/arch/powerpc/platforms/52xx/mpc52xx_common.c
> index 6e90531..41f3a7e 100644
> --- a/arch/powerpc/platforms/52xx/mpc52xx_common.c
> +++ b/arch/powerpc/platforms/52xx/mpc52xx_common.c
> @@ -325,12 +325,16 @@ int mpc5200_psc_ac97_gpio_reset(int psc_number)
> clrbits32(&simple_gpio->simple_dvo, sync | out);
> clrbits8(&wkup_gpio->wkup_dvo, reset);
> - /* wait at lease 1 us */
> - udelay(2);
> + /* wait for 1 us */
> + udelay(1);
> /* Deassert reset */
> setbits8(&wkup_gpio->wkup_dvo, reset);
> + /* wait at least 200ns */
> + /* 7 ~= (200ns * timebase) / ns2sec */
> + __delay(7);
> /* Restore pin-muxing */
> out_be32(&simple_gpio->port_config, mux);
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