On Mon, 5 Mar 2012 15:10:04 -0800, Kevin Hilman <[email protected]> wrote:
> While both level- and edge-triggered GPIOs are capable of generating
> interrupts, only edge-triggered GPIOs are capable of generating a
> module-level wakeup to the PRCM (c.f. 34xx NDA TRM section 25.5.3.2.)
>
> In order to ensure that devices using level-triggered GPIOs as
> interrupts can also cause wakeups (e.g. from idle), this patch enables
> edge-triggering for wakeup-enabled, level-triggered GPIOs when a GPIO
> bank is runtime-suspended (which also happens during idle.)
>
> This fixes a problem found in GPMC-connected network cards with GPIO
> interrupts (e.g. smsc911x on Zoom3, Overo, ...) where network booting
> with NFSroot was very slow since the GPIO IRQs used by the NIC were
> not generating PRCM wakeups, and thus not waking the system from idle.
> NOTE: until v3.3, this boot-time problem was somewhat masked because
> the UART init prevented WFI during boot until the full serial driver
> was available. Preventing WFI allowed regular GPIO interrupts to fire
> and this problem was not seen. After the UART runtime PM cleanups, we
> no longer avoid WFI during boot, so GPIO IRQs that were not causing
> wakeups resulted in very slow IRQ response times.
>
> Tested on platforms using level-triggered GPIOs for network IRQs using
> the SMSC911x NIC: 3530/Overo and 3630/Zoom3.
>
> Reported-by: Tony Lindgren <[email protected]>
> Tested-by: Tarun Kanti DebBarma <[email protected]>
> Tested-by: Tony Lindgren <[email protected]>
> Signed-off-by: Kevin Hilman <[email protected]>
Applied, thx.
g.
> ---
> Grant, here's another one for your gpio/next branch, and applies on
> top of the for_3.4/gpio/runtime-pm-cleanup branch you've already
> pulled from me. While it's a fix, it's not a regressions since
> this problem has been around for awhile, so it can be for 3.4.
>
> drivers/gpio/gpio-omap.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index f49bd6f..752ae9b 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -1196,8 +1196,30 @@ static int omap_gpio_runtime_suspend(struct device
> *dev)
> struct gpio_bank *bank = platform_get_drvdata(pdev);
> u32 l1 = 0, l2 = 0;
> unsigned long flags;
> + u32 wake_low, wake_hi;
>
> spin_lock_irqsave(&bank->lock, flags);
> +
> + /*
> + * Only edges can generate a wakeup event to the PRCM.
> + *
> + * Therefore, ensure any wake-up capable GPIOs have
> + * edge-detection enabled before going idle to ensure a wakeup
> + * to the PRCM is generated on a GPIO transition. (c.f. 34xx
> + * NDA TRM 25.5.3.1)
> + *
> + * The normal values will be restored upon ->runtime_resume()
> + * by writing back the values saved in bank->context.
> + */
> + wake_low = bank->context.leveldetect0 & bank->context.wake_en;
> + if (wake_low)
> + __raw_writel(wake_low | bank->context.fallingdetect,
> + bank->base + bank->regs->fallingdetect);
> + wake_hi = bank->context.leveldetect1 & bank->context.wake_en;
> + if (wake_hi)
> + __raw_writel(wake_hi | bank->context.risingdetect,
> + bank->base + bank->regs->risingdetect);
> +
> if (bank->power_mode != OFF_MODE) {
> bank->power_mode = 0;
> goto update_gpio_context_count;
> @@ -1246,6 +1268,18 @@ static int omap_gpio_runtime_resume(struct device *dev)
>
> spin_lock_irqsave(&bank->lock, flags);
> _gpio_dbck_enable(bank);
> +
> + /*
> + * In ->runtime_suspend(), level-triggered, wakeup-enabled
> + * GPIOs were set to edge trigger also in order to be able to
> + * generate a PRCM wakeup. Here we restore the
> + * pre-runtime_suspend() values for edge triggering.
> + */
> + __raw_writel(bank->context.fallingdetect,
> + bank->base + bank->regs->fallingdetect);
> + __raw_writel(bank->context.risingdetect,
> + bank->base + bank->regs->risingdetect);
> +
> if (!bank->enabled_non_wakeup_gpios || !bank->workaround_enabled) {
> spin_unlock_irqrestore(&bank->lock, flags);
> return 0;
> --
> 1.7.9.2
>
--
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies,Ltd.
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