Re: [PATCH 6/7] remoteproc: qcom_q6v5_pas: Add hwspinlock bust on stop

[Mukesh Ojha]

On 5/17/2024 4:28 AM, Chris Lew wrote:
> From: Richard Maina <quic_rmaina@xxxxxxxxxxx>
>
> When remoteproc goes down unexpectedly this results in a state where any
> acquired hwspinlocks will remain locked possibly resulting in deadlock.
> In order to ensure all locks are freed we include a call to
> hwspin_lock_bust() during remoteproc shutdown.
>
> For qcom_q6v5_pas remoteprocs, each remoteproc has an assigned id that
> is used to take the hwspinlock. Remoteproc should use this id to try and
> bust the lock on remoteproc stop.
>
> This edge case only occurs with q6v5_pas watchdog crashes. The error
> fatal case has handling to clear the hwspinlock before the error fatal
> interrupt is triggered.
>
> Signed-off-by: Richard Maina <quic_rmaina@xxxxxxxxxxx>
> Signed-off-by: Chris Lew <quic_clew@xxxxxxxxxxx>
> ---
>   drivers/remoteproc/qcom_q6v5_pas.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
>
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index 54d8005d40a3..57178fcb9aa3 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -10,6 +10,7 @@
>   #include <linux/clk.h>
>   #include <linux/delay.h>
>   #include <linux/firmware.h>
> +#include <linux/hwspinlock.h>
>   #include <linux/interrupt.h>
>   #include <linux/kernel.h>
>   #include <linux/module.h>
> @@ -52,6 +53,7 @@ struct adsp_data {
>   	const char *ssr_name;
>   	const char *sysmon_name;
>   	int ssctl_id;
> +	int hwlock_id;
>   
>   	int region_assign_idx;
>   	int region_assign_count;
> @@ -84,6 +86,9 @@ struct qcom_adsp {
>   	bool decrypt_shutdown;
>   	const char *info_name;
>   
> +	struct hwspinlock *hwlock;
> +	int hwlock_id;
> +
>   	const struct firmware *firmware;
>   	const struct firmware *dtb_firmware;
>   
> @@ -399,6 +404,12 @@ static int adsp_stop(struct rproc *rproc)
>   	if (handover)
>   		qcom_pas_handover(&adsp->q6v5);
>   
> +	if (adsp->hwlock) {
> +		ret = hwspin_lock_bust(adsp->hwlock, adsp->hwlock_id);
> +		if (ret)
> +			dev_info(adsp->dev, "failed to bust hwspinlock\n");
> +	}
> +

What if recovery is disabled, fatal case is clearing the hwspinlock but
wdog case is not, right ?

-Mukesh