Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <da6bee63-6a79-2341-e099-d26b53fb557f@foss.st.com>
Date:   Thu, 24 Feb 2022 15:08:27 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.5.0
Subject: Re: [PATCH V2] remoteproc: support self recovery after rproc crash
Content-Language: en-US
From:   Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
To:     "Peng Fan (OSS)" <peng.fan@oss.nxp.com>,
        <bjorn.andersson@linaro.org>, <mathieu.poirier@linaro.org>,
        <linux-remoteproc@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
CC:     Peng Fan <peng.fan@nxp.com>
References: <20220126085120.3397450-1-peng.fan@oss.nxp.com>
 <67ddf940-6f87-d8cc-8dc6-29a39a022265@foss.st.com>
In-Reply-To: <67ddf940-6f87-d8cc-8dc6-29a39a022265@foss.st.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Peng,

On 2/14/22 19:41, Arnaud POULIQUEN wrote:
> Hi Peng,
> 
> On 1/26/22 09:51, Peng Fan (OSS) wrote:
>> From: Peng Fan <peng.fan@nxp.com>
>>
>> Current logic only support main processor to stop/start the remote
>> processor after rproc crash. However to SoC, such as i.MX8QM/QXP, the
>> remote processor could do self recovery after crash and trigger watchdog
>> reboot. It does not need main processor to load image, stop/start M4
>> core.
> 
> 
> On stm32mp1 platform the remote processor watchdog generates an early interrupt
> that could be used to detach and reattach before the reset of the remote processor.
> I need to test race condition,but I suppose that this should works if the resource
> table is not reinitialized by the remote processor firmware.
> 
> Another option for the stm32mp1 is that remoteproc manages the reset of the 
> remote processor.
> For instance this allows to save a core-dump before manually resetting the remote
> processor.
> But looks like this use case can be handled later, as mentioned below. 
> 
>>
>> This patch add a new flag to indicate whether the SoC has self recovery
>> capability. And introduce two functions: rproc_self_recovery,
>> rproc_assisted_recovery for the two cases. Assisted recovery is as
>> before, let main processor to help recovery, while self recovery is
>> recover itself withou help. To self recovery, we only do detach and
>> attach.
> 
> 
>>
>> Signed-off-by: Peng Fan <peng.fan@nxp.com>
>> ---
>>
>> V2:
>>  Nothing change in V2.
>>  Only move this patch out from
>>  https://patchwork.kernel.org/project/linux-remoteproc/list/?series=604364
>>
>>  drivers/remoteproc/remoteproc_core.c | 66 ++++++++++++++++++++--------
>>  include/linux/remoteproc.h           |  2 +
>>  2 files changed, 49 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
>> index 69f51acf235e..4bd5544dab8f 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -1887,6 +1887,49 @@ static int __rproc_detach(struct rproc *rproc)
>>  	return 0;
>>  }
>>  
>> +static int rproc_self_recovery(struct rproc *rproc)
>> +{
>> +	int ret;
>> +
>> +	mutex_unlock(&rproc->lock);
>> +	ret = rproc_detach(rproc);
>> +	mutex_lock(&rproc->lock);
>> +	if (ret)
>> +		return ret;
> 
> Here we would want to perform a core dump and manually reset the
> co-processor.
> I suppose that a new rproc ops could be called here in a next step.
> 
>> +
>> +	if (atomic_inc_return(&rproc->power) > 1)
>> +		return 0;
> 
> Do you identify a use case that needs to test rproc->power to
> skip the attach?
> If yes could you add a comment to describe it?
> 
>> +	return rproc_attach(rproc);
>> +}
>> +
>> +static int rproc_assisted_recovery(struct rproc *rproc)
>> +{
>> +	const struct firmware *firmware_p;
>> +	struct device *dev = &rproc->dev;
>> +	int ret;
>> +
>> +	ret = rproc_stop(rproc, true);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* generate coredump */
>> +	rproc->ops->coredump(rproc);
>> +
>> +	/* load firmware */
>> +	ret = request_firmware(&firmware_p, rproc->firmware, dev);
>> +	if (ret < 0) {
>> +		dev_err(dev, "request_firmware failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* boot the remote processor up again */
>> +	ret = rproc_start(rproc, firmware_p);
>> +
>> +	release_firmware(firmware_p);
>> +
>> +	return ret;
>> +}
>> +
>>  /**
>>   * rproc_trigger_recovery() - recover a remoteproc
>>   * @rproc: the remote processor
>> @@ -1901,7 +1944,6 @@ static int __rproc_detach(struct rproc *rproc)
>>   */
>>  int rproc_trigger_recovery(struct rproc *rproc)
>>  {
>> -	const struct firmware *firmware_p;
>>  	struct device *dev = &rproc->dev;
>>  	int ret;
>>  
>> @@ -1915,24 +1957,10 @@ int rproc_trigger_recovery(struct rproc *rproc)
>>  
>>  	dev_err(dev, "recovering %s\n", rproc->name);
>>  
>> -	ret = rproc_stop(rproc, true);
>> -	if (ret)
>> -		goto unlock_mutex;
>> -
>> -	/* generate coredump */
>> -	rproc->ops->coredump(rproc);
>> -
>> -	/* load firmware */
>> -	ret = request_firmware(&firmware_p, rproc->firmware, dev);
>> -	if (ret < 0) {
>> -		dev_err(dev, "request_firmware failed: %d\n", ret);
>> -		goto unlock_mutex;
>> -	}
>> -
>> -	/* boot the remote processor up again */
>> -	ret = rproc_start(rproc, firmware_p);
>> -
>> -	release_firmware(firmware_p);
>> +	if (rproc->self_recovery)
>> +		ret = rproc_self_recovery(rproc);
> 
> If some platforms have to manually reset the remote processor (without
> reloading the firmware) the name could not be relevant...
> 
> Following comments are only suggestions that needs to be commented by maintainers
> 
> What about rproc_attach_recovery ?
> 
>> +	else
>> +		ret = rproc_assisted_recovery(rproc);
> 
> and rproc_firmware_recovery ?
> 
> 
>>  
>>  unlock_mutex:
>>  	mutex_unlock(&rproc->lock);
>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>> index e0600e1e5c17..b32ef46f8aa4 100644
>> --- a/include/linux/remoteproc.h
>> +++ b/include/linux/remoteproc.h
>> @@ -529,6 +529,7 @@ struct rproc_dump_segment {
>>   * @elf_machine: firmware ELF machine
>>   * @cdev: character device of the rproc
>>   * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
>> + * @self_recovery: flag to indicate if remoteproc support self recovery
>>   */
>>  struct rproc {
>>  	struct list_head node;
>> @@ -568,6 +569,7 @@ struct rproc {
>>  	u16 elf_machine;
>>  	struct cdev cdev;
>>  	bool cdev_put_on_release;
>> +	bool self_recovery;
> 
> This bool seems needed because we have lost the previous state before crash. 
> I wonder if a new rproc->state such as RPROC_REBOOT could avoid this boolean.
> 
> 
> I will try to test you patch on stm32mp1 next week

I performed few tests on the stm32mp1 with your patch.
Thanks to the resetting of the resource tables on detachment, this works quite well.

Regards,
Arnaud

> 
> Regards,
> Arnaud
> 
>>  };
>>  
>>  /**