[PATCH 2/4] ALSA: pxa27x: fix ac97 warm reset bug work-around code
Igor Grinberg
grinberg at compulab.co.il
Mon Jan 7 04:31:51 EST 2013
On 01/06/13 21:13, Mike Dunn wrote:
> This patch fixes some code that implements a work-around to a hardware bug in
> the ac97 controller on the pxa27x. A bug in the controller's warm reset
> functionality requires that the mfp used by the controller as the AC97_nRESET
> line be temporarily reconfigured as a generic output gpio (AF0) and manually
> held high for the duration of the warm reset cycle. This is what was done in
> the original code, but it was broken long ago by commit
> fb1bf8cd13bfa7ed0364ab0d82f717fc020d35f6
> ([ARM] pxa: introduce processor specific pxa27x_assert_ac97reset())
> which changed the mfp to a GPIO input instead of a high output.
>
> Tested on a palm treo 680 machine. Reportedly, this broken code only prevents a
> warm reset on hardware that lacks a pull-up on the line, which appears to be the
> case for me.
>
> Signed-off-by: Mike Dunn <mikedunn at newsguy.com>
> ---
>
> An earlier version of this patch failed to drive the output high as intended.
> Thanks again Igor! Warm reset now works and need not be skipped.
>
> arch/arm/mach-pxa/include/mach/mfp-pxa27x.h | 3 +++
> arch/arm/mach-pxa/pxa27x.c | 13 +++++++++++--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h b/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
> index a611ad3..8281e17 100644
> --- a/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
> +++ b/arch/arm/mach-pxa/include/mach/mfp-pxa27x.h
> @@ -463,6 +463,9 @@
> GPIO76_LCD_PCLK, \
> GPIO77_LCD_BIAS
>
> +/* these enable a work-around for a hw bug in pxa27x during ac97 warm reset */
> +#define GPIO113_AC97_nRESET_GPIO_HIGH MFP_CFG_OUT(GPIO113, AF0, DRIVE_HIGH)
> +#define GPIO95_AC97_nRESET_GPIO_HIGH MFP_CFG_OUT(GPIO95, AF0, DRIVE_HIGH)
Do we really need to change the LPM? Because DRIVE_* only affect LPM.
>
> extern int keypad_set_wake(unsigned int on);
> #endif /* __ASM_ARCH_MFP_PXA27X_H */
> diff --git a/arch/arm/mach-pxa/pxa27x.c b/arch/arm/mach-pxa/pxa27x.c
> index 8047ee0..eea90fe 100644
> --- a/arch/arm/mach-pxa/pxa27x.c
> +++ b/arch/arm/mach-pxa/pxa27x.c
> @@ -47,14 +47,23 @@ void pxa27x_clear_otgph(void)
> EXPORT_SYMBOL(pxa27x_clear_otgph);
>
> static unsigned long ac97_reset_config[] = {
> - GPIO113_GPIO,
> + GPIO113_AC97_nRESET_GPIO_HIGH,
> GPIO113_AC97_nRESET,
> - GPIO95_GPIO,
> + GPIO95_AC97_nRESET_GPIO_HIGH,
> GPIO95_AC97_nRESET,
> };
>
> void pxa27x_assert_ac97reset(int reset_gpio, int on)
> {
> + /* set direction and level before switching from ac97 alt fn to gpio */
> + if (on) {
> + int ret = gpio_direction_output(reset_gpio, 1);
> + if (ret) {
> + pr_err("%s: gpio_direction_output failed: %d\n",
> + __func__, ret);
> + return;
> + }
> + }
Same concern, as you raised in reply to my patch.
As pxa2xx_mfp_config() changes GPDR for input,
the above should be done after the MFP AF0 switch.
> if (reset_gpio == 113)
> pxa2xx_mfp_config(on ? &ac97_reset_config[0] :
> &ac97_reset_config[1], 1);
--
Regards,
Igor.
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