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Subject: Re: [PATCH v4 2/2] remoteproc: stm32: add capability to detach
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
CC:     Ohad Ben-Cohen <ohad@wizery.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Rob Herring <robh@kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-remoteproc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20210331073347.8293-1-arnaud.pouliquen@foss.st.com>
 <20210331073347.8293-3-arnaud.pouliquen@foss.st.com>
 <YHYOd/vqeZCiqkpJ@builder.lan>
From:   Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
Message-ID: <3df5317b-d28a-9362-6876-99442fdb8ef5@foss.st.com>
Date:   Wed, 14 Apr 2021 09:23:56 +0200
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Hello Bjorn

On 4/13/21 11:34 PM, Bjorn Andersson wrote:
> 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.

Thanks for pointing this out, you are right, the mailbox driver is stm32_ipcc
and it only sends a signal to the remote processor.

As message can be queued by the mailbox framework using a local variable seems
not a good option. As this code is a copy/past of the kick and stop?
I propose to get this one and I will send a new patch to fix the usage in the
whole driver.

Thanks,
Arnaud

> 
> 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
>>