Message-Id: <VUEPBQ.GMXO6YRLF7N22@crapouillou.net>
Date:   Wed, 10 Jun 2020 11:40:07 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Suman Anna <s-anna@...com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Arnaud Pouliquen <arnaud.pouliquen@...com>,
        Loic Pallardy <loic.pallardy@...com>, od@...c.me,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Tero Kristo <t-kristo@...com>
Subject: Re: [PATCH v7 3/5] remoteproc: Add support for runtime PM

Hi,

Le lun. 8 juin 2020 à 18:10, Suman Anna <s-anna@...com> a écrit :
> Hi Paul,
> 
> On 6/8/20 5:46 PM, Paul Cercueil wrote:
>> Hi Suman,
>> 
>>>>> On 5/15/20 5:43 AM, Paul Cercueil wrote:
>>>>>> Call pm_runtime_get_sync() before the firmware is loaded, and
>>>>>> pm_runtime_put() after the remote processor has been stopped.
>>>>>> 
>>>>>> Even though the remoteproc device has no PM callbacks, this 
>>>>>> allows the
>>>>>> parent device's PM callbacks to be properly called.
>>>>> 
>>>>> I see this patch staged now for 5.8, and the latest -next branch 
>>>>> has broken the pm-runtime autosuspend feature we have in 
>>>>> the OMAP remoteproc driver. See commit 5f31b232c674 
>>>>> ("remoteproc/omap: Add support for runtime 
>>>>> auto-suspend/resume").
>>>>> 
>>>>> What was the original purpose of this patch, because there can be 
>>>>> differing backends across different SoCs.
>>>> 
>>>> Did you try pm_suspend_ignore_children()? It looks like it was 
>>>> made for your use-case.
>>> 
>>> Sorry for the delay in getting back. So, using 
>>> pm_suspend_ignore_children() does fix my current issue.
>>> 
>>> But I still fail to see the original purpose of this patch in the 
>>> remoteproc core especially given that the core itself does not 
>>> have any callbacks. If the sole intention was to call the parent 
>>> pdev's callbacks, then I feel that state-machine is better 
>>> managed within that particular platform driver itself, as the 
>>> sequencing/device management can vary with different platform 
>>> drivers.
>> 
>> The problem is that with Ingenic SoCs some clocks must be enabled in 
>> order to load the firmware, and the core doesn't give you an option 
>> to register a callback to be called before loading it.
> 
> Yep, I have similar usage in one of my remoteproc drivers (see 
> keystone_remoteproc.c), and I think this all stems from the need to 
> use/support loading into a processor's internal memories. My driver 
> does leverage the pm-clks backend plugged into pm_runtime, so you 
> won't see explicit calls on the clocks.
> 
> I guess the question is what exact PM features you are looking for 
> with the Ingenic SoC. I do see you are using pm_runtime autosuspend, 
> and your callbacks are managing the clocks, but reset is managed only 
> in start/stop.
> 
>> The first version of my patchset added .prepare/.unprepare 
>> callbacks to the struct rproc_ops, but the feedback from the 
>> maintainers was that I should do it via runtime PM. However, it was 
>> not possible to keep it contained in the driver, since again the 
>> core doesn't provide a "prepare" callback, so no place to call 
>> pm_runtime_get_sync().
> FWIW, the .prepare/.unprepare callbacks is actually now part of the 
> rproc core. Looks like multiple developers had a need for this, and 
> this functionality went in at the same time as your driver :). Not 
> sure if you looked up the prior patches, I leveraged the patch that 
> Loic had submitted a long-time ago, and a revised version of it is 
> now part of 5.8-rc1.

WTF maintainers, you refuse my patchset for adding a 
.prepare/.unprepare, ask me to do it via runtime PM, then merge another 
patchset that adds these callback. At least be constant in your 
decisions.

Anyway, now we have two methods added to linux-next for doing the exact 
same thing. What should we do about it?

-Paul

> So we settled with having runtime
>> PM in the core without callbacks, which will trigger the runtime PM 
>> callbacks of the driver at the right moment.
> 
> Looks like we can do some cleanup on the Ingenic SoC driver depending 
> on the features you want.
> 
> regards
> Suman
> 
>> 
>> Sorry if that caused you trouble.
>> 
>> Cheers,
>> -Paul
>>>>> 
>> 
>>>>> 
>>>>>> 
>>>>>> 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
>>>>>>      v6: Instead of prepare/unprepare callbacks, use PM runtime 
>>>>>> callbacks
>>>>>>      v7: Check return value of pm_runtime_get_sync()
>>>>>> 
>>>>>>   drivers/remoteproc/remoteproc_core.c | 17 ++++++++++++++++-
>>>>>>   1 file changed, 16 insertions(+), 1 deletion(-)
>>>>>> 
>>>>>> diff --git a/drivers/remoteproc/remoteproc_core.c 
>>>>>> b/drivers/remoteproc/remoteproc_core.c
>>>>>> index a7f96bc98406..e33d1ef27981 100644
>>>>>> --- a/drivers/remoteproc/remoteproc_core.c
>>>>>> +++ b/drivers/remoteproc/remoteproc_core.c
>>>>>> @@ -29,6 +29,7 @@
>>>>>>   #include <linux/devcoredump.h>
>>>>>>   #include <linux/rculist.h>
>>>>>>   #include <linux/remoteproc.h>
>>>>>> +#include <linux/pm_runtime.h>
>>>>>>   #include <linux/iommu.h>
>>>>>>   #include <linux/idr.h>
>>>>>>   #include <linux/elf.h>
>>>>>> @@ -1382,6 +1383,12 @@ static int rproc_fw_boot(struct rproc 
>>>>>> *rproc, const struct firmware *fw)
>>>>>>       if (ret)
>>>>>>           return ret;
>>>>>>   +    ret = pm_runtime_get_sync(dev);
>>>>>> +    if (ret < 0) {
>>>>>> +        dev_err(dev, "pm_runtime_get_sync failed: %d\n", ret);
>>>>>> +        return ret;
>>>>>> +    }
>>>>>> +
>>>>>>       dev_info(dev, "Booting fw image %s, size %zd\n", name, 
>>>>>> fw->size);
>>>>>>         /*
>>>>>> @@ -1391,7 +1398,7 @@ 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 put_pm_runtime;
>>>>>>       }
>>>>>>         rproc->bootaddr = rproc_get_boot_addr(rproc, fw);
>>>>>> @@ -1435,6 +1442,8 @@ static int rproc_fw_boot(struct rproc 
>>>>>> *rproc, const struct firmware *fw)
>>>>>>       rproc->table_ptr = NULL;
>>>>>>   disable_iommu:
>>>>>>       rproc_disable_iommu(rproc);
>>>>>> +put_pm_runtime:
>>>>>> +    pm_runtime_put(dev);
>>>>>>       return ret;
>>>>>>   }
>>>>>>   @@ -1840,6 +1849,8 @@ void rproc_shutdown(struct rproc *rproc)
>>>>>>         rproc_disable_iommu(rproc);
>>>>>>   +    pm_runtime_put(dev);
>>>>>> +
>>>>>>       /* Free the copy of the resource table */
>>>>>>       kfree(rproc->cached_table);
>>>>>>       rproc->cached_table = NULL;
>>>>>> @@ -2118,6 +2129,9 @@ struct rproc *rproc_alloc(struct device 
>>>>>> *dev, const char *name,
>>>>>>         rproc->state = RPROC_OFFLINE;
>>>>>>   +    pm_runtime_no_callbacks(&rproc->dev);
>>>>>> +    pm_runtime_enable(&rproc->dev);
>>>>>> +
>>>>>>       return rproc;
>>>>>>   }
>>>>>>   EXPORT_SYMBOL(rproc_alloc);
>>>>>> @@ -2133,6 +2147,7 @@ EXPORT_SYMBOL(rproc_alloc);
>>>>>>    */
>>>>>>   void rproc_free(struct rproc *rproc)
>>>>>>   {
>>>>>> +    pm_runtime_disable(&rproc->dev);
>>>>>>       put_device(&rproc->dev);
>>>>>>   }
>>>>>>   EXPORT_SYMBOL(rproc_free);
>>>>>> 
>>>>> 
>> 
>> 
> 

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