[alsa-devel] [PATCH v7 12/13] slimbus: qcom: Add runtime-pm support using clock-pause

[Charles Keepax]

On Wed, Nov 15, 2017 at 02:10:42PM +0000, srinivas.kandagatla at linaro.org wrote:
> From: Sagar Dharia <sdharia at codeaurora.org>
> 
> Slimbus HW mandates that clock-pause sequence has to be executed
> before disabling relevant interface and core clocks.
> Runtime-PM's autosuspend feature is used here to enter/exit low
> power mode for Qualcomm's Slimbus controller. Autosuspend feature
> enables driver to avoid changing power-modes too frequently since
> entering clock-pause is an expensive sequence
> 
> Signed-off-by: Sagar Dharia <sdharia at codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> ---
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int qcom_slim_suspend(struct device *dev)
> +{
> +	int ret = 0;
> +
> +	if (!pm_runtime_enabled(dev) ||
> +		(!pm_runtime_suspended(dev))) {
> +		dev_dbg(dev, "system suspend");
> +		ret = qcom_slim_runtime_suspend(dev);
> +	}
> +
> +	/*
> +	 * If the clock pause failed due to active channels, there is
> +	 * a possibility that some audio stream is active during suspend.
> +	 * (e.g. modem usecase during suspend)
> +	 * We dont want to return suspend failure in that case so that
> +	 * display and relevant components can still go to suspend.
> +	 * If there is some other error, then it should prevent
> +	 * system level suspend
> +	 */
> +	if (ret == -EISCONN)
> +		ret = 0;

Who actually returns the EISCONN for this to catch? Or will that
be added to slim_ctrl_clk_pause once support for the audio
channels is added?

Thanks,
Charles

> +
> +	return ret;
> +}