Re: [PATCH v4 2/2] remoteproc: stm32: add capability to detach

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Wed 31 Mar 02:33 CDT 2021, Arnaud Pouliquen wrote:

> A mechanism similar to the shutdown mailbox signal is implemented to
> detach a remote processor.
> 
> Upon detachment, a signal is sent to the remote firmware, allowing it
> to perform specific actions such as stopping rpmsg communication.
> 
> The Cortex-M hold boot is also disabled to allow the remote processor
> to restart in case of crash.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  drivers/remoteproc/stm32_rproc.c | 39 ++++++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
> index 3d45f51de4d0..7353f9e7e7af 100644
> --- a/drivers/remoteproc/stm32_rproc.c
> +++ b/drivers/remoteproc/stm32_rproc.c
> @@ -28,7 +28,7 @@
>  #define RELEASE_BOOT		1
>  
>  #define MBOX_NB_VQ		2
> -#define MBOX_NB_MBX		3
> +#define MBOX_NB_MBX		4
>  
>  #define STM32_SMC_RCC		0x82001000
>  #define STM32_SMC_REG_WRITE	0x1
> @@ -38,6 +38,7 @@
>  #define STM32_MBX_VQ1		"vq1"
>  #define STM32_MBX_VQ1_ID	1
>  #define STM32_MBX_SHUTDOWN	"shutdown"
> +#define STM32_MBX_DETACH	"detach"
>  
>  #define RSC_TBL_SIZE		1024
>  
> @@ -336,6 +337,15 @@ static const struct stm32_mbox stm32_rproc_mbox[MBOX_NB_MBX] = {
>  			.tx_done = NULL,
>  			.tx_tout = 500, /* 500 ms time out */
>  		},
> +	},
> +	{
> +		.name = STM32_MBX_DETACH,
> +		.vq_id = -1,
> +		.client = {
> +			.tx_block = true,
> +			.tx_done = NULL,
> +			.tx_tout = 200, /* 200 ms time out to detach should be fair enough */
> +		},
>  	}
>  };
>  
> @@ -461,6 +471,25 @@ static int stm32_rproc_attach(struct rproc *rproc)
>  	return stm32_rproc_set_hold_boot(rproc, true);
>  }
>  
> +static int stm32_rproc_detach(struct rproc *rproc)
> +{
> +	struct stm32_rproc *ddata = rproc->priv;
> +	int err, dummy_data, idx;
> +
> +	/* Inform the remote processor of the detach */
> +	idx = stm32_rproc_mbox_idx(rproc, STM32_MBX_DETACH);
> +	if (idx >= 0 && ddata->mb[idx].chan) {
> +		/* A dummy data is sent to allow to block on transmit */
> +		err = mbox_send_message(ddata->mb[idx].chan,
> +					&dummy_data);

Seems I posted my comment on v1, rather than this latest version. Please
let me know if we should do anything about this dummy_data.

Regards,
Bjorn

> +		if (err < 0)
> +			dev_warn(&rproc->dev, "warning: remote FW detach without ack\n");
> +	}
> +
> +	/* Allow remote processor to auto-reboot */
> +	return stm32_rproc_set_hold_boot(rproc, false);
> +}
> +
>  static int stm32_rproc_stop(struct rproc *rproc)
>  {
>  	struct stm32_rproc *ddata = rproc->priv;
> @@ -597,7 +626,12 @@ stm32_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
>  	}
>  
>  done:
> -	/* Assuming the resource table fits in 1kB is fair */
> +	/*
> +	 * Assuming the resource table fits in 1kB is fair.
> +	 * Notice for the detach, that this 1 kB memory area has to be reserved in the coprocessor
> +	 * firmware for the resource table. On detach, the remoteproc core re-initializes this
> +	 * entire area by overwriting it with the initial values stored in rproc->clean_table.
> +	 */
>  	*table_sz = RSC_TBL_SIZE;
>  	return (struct resource_table *)ddata->rsc_va;
>  }
> @@ -607,6 +641,7 @@ static const struct rproc_ops st_rproc_ops = {
>  	.start		= stm32_rproc_start,
>  	.stop		= stm32_rproc_stop,
>  	.attach		= stm32_rproc_attach,
> +	.detach		= stm32_rproc_detach,
>  	.kick		= stm32_rproc_kick,
>  	.load		= rproc_elf_load_segments,
>  	.parse_fw	= stm32_rproc_parse_fw,
> -- 
> 2.17.1
>