linux-kernel - Re: [PATCH v5 3/5] remoteproc: Add prepare/unprepare callbacks

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Date:   Mon, 24 Feb 2020 12:25:14 -0300
From:   Paul Cercueil <paul@...pouillou.net>
To:     Arnaud POULIQUEN <arnaud.pouliquen@...com>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, od@...c.me,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/5] remoteproc: Add prepare/unprepare callbacks

Hi Arnaud,


Le mar., févr. 18, 2020 at 17:31, Arnaud POULIQUEN 
<arnaud.pouliquen@...com> a écrit :
> Hi Paul,
> 
> I still wonder about the use of pm_runtime mechanism as a more 
> generic alternative...

The use of pm_runtime is perfect if CONFIG_PM is enabled, but otherwise 
it's a bit cumbersome, as the clocks must be enabled in the probe.

-Paul

> Else just a minor remark inline.
> 
> On 2/11/20 3:26 PM, Paul Cercueil wrote:
>>  The .prepare() callback is called before the firmware is loaded to
>>  memory. This is useful for instance in the case where some setup is
>>  required for the memory to be accessible.
>> 
>>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  ---
>> 
>>  Notes:
>>      v2-v4: No change
>>      v5: Move calls to prepare/unprepare to 
>> rproc_fw_boot/rproc_shutdown
>> 
>>   drivers/remoteproc/remoteproc_core.c | 16 +++++++++++++++-
>>   include/linux/remoteproc.h           |  4 ++++
>>   2 files changed, 19 insertions(+), 1 deletion(-)
>> 
>>  diff --git a/drivers/remoteproc/remoteproc_core.c 
>> b/drivers/remoteproc/remoteproc_core.c
>>  index fe5c7a2f9767..022b927e176b 100644
>>  --- a/drivers/remoteproc/remoteproc_core.c
>>  +++ b/drivers/remoteproc/remoteproc_core.c
>>  @@ -1373,6 +1373,14 @@ static int rproc_fw_boot(struct rproc 
>> *rproc, const struct firmware *fw)
>> 
>>   	dev_info(dev, "Booting fw image %s, size %zd\n", name, fw->size);
>> 
>>  +	if (rproc->ops->prepare) {
>>  +		ret = rproc->ops->prepare(rproc);
>>  +		if (ret) {
>>  +			dev_err(dev, "Failed to prepare rproc: %d\n", ret);
>>  +			return ret;
>>  +		}
>>  +	}
>>  +
>>   	/*
>>   	 * if enabling an IOMMU isn't relevant for this rproc, this is
>>   	 * just a nop
>>  @@ -1380,7 +1388,7 @@ static int rproc_fw_boot(struct rproc *rproc, 
>> const struct firmware *fw)
>>   	ret = rproc_enable_iommu(rproc);
>>   	if (ret) {
>>   		dev_err(dev, "can't enable iommu: %d\n", ret);
>>  -		return ret;
>>  +		goto unprepare_rproc;
>>   	}
>> 
>>   	rproc->bootaddr = rproc_get_boot_addr(rproc, fw);
>>  @@ -1424,6 +1432,9 @@ static int rproc_fw_boot(struct rproc *rproc, 
>> const struct firmware *fw)
>>   	rproc->table_ptr = NULL;
>>   disable_iommu:
>>   	rproc_disable_iommu(rproc);
>>  +unprepare_rproc:
>>  +	if (rproc->ops->unprepare)
>>  +		rproc->ops->unprepare(rproc);
>>   	return ret;
>>   }
>> 
>>  @@ -1823,6 +1834,9 @@ void rproc_shutdown(struct rproc *rproc)
>> 
>>   	rproc_disable_iommu(rproc);
>> 
>>  +	if (rproc->ops->unprepare)
>>  +		rproc->ops->unprepare(rproc);
>>  +
>>   	/* Free the copy of the resource table */
>>   	kfree(rproc->cached_table);
>>   	rproc->cached_table = NULL;
>>  diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>>  index 5f201f0c86c3..a6272d1ba384 100644
>>  --- a/include/linux/remoteproc.h
>>  +++ b/include/linux/remoteproc.h
>>  @@ -355,6 +355,8 @@ enum rsc_handling_status {
>> 
>>   /**
>>    * struct rproc_ops - platform-specific device handlers
>>  + * @prepare:	prepare the device for power up (before the firmware 
>> is loaded)
>>  + * @unprepare:	unprepare the device after it is stopped
> 
> Would be nice here to precise that these functions are optional
> you can look at rproc_ops struct for example.
> 
> Regards,
> Arnaud
> 
>>    * @start:	power on the device and boot it
>>    * @stop:	power off the device
>>    * @kick:	kick a virtqueue (virtqueue id given as a parameter)
>>  @@ -371,6 +373,8 @@ enum rsc_handling_status {
>>    * @get_boot_addr:	get boot address to entry point specified in 
>> firmware
>>    */
>>   struct rproc_ops {
>>  +	int (*prepare)(struct rproc *rproc);
>>  +	void (*unprepare)(struct rproc *rproc);
>>   	int (*start)(struct rproc *rproc);
>>   	int (*stop)(struct rproc *rproc);
>>   	void (*kick)(struct rproc *rproc, int vqid);
>>