[PATCH] powerpc/5200: tighten up ac97 reset timing
emillbrandt at dekaresearch.com
Sat Sep 4 02:17:33 EST 2010
On Fri, 3 Sep 2010 at 12:02:09 Wolfram Sang wrote:
> 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 at 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
>> 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);
Is ndelay defined for powerpc? I was under the impression that it was
being redefined to udelay in linux/delay.h.
static inline void ndelay(unsigned long x)
#define ndelay(x) ndelay(x)
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