On 4/2/20 3:42 PM, Mathieu Poirier wrote:
> Hi Suman,
>
> On Tue, Mar 31, 2020 at 05:35:58PM -0500, Suman Anna wrote:
>> Hi Mathieu,
>>
>> On 3/30/20 6:49 PM, Mathieu Poirier wrote:
>>> On Fri, Mar 27, 2020 at 02:04:36PM +0000, Loic PALLARDY wrote:
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>>>>> Sent: mardi 24 mars 2020 22:46
>>>>> To: bjorn.andersson@xxxxxxxxxx
>>>>> Cc: ohad@xxxxxxxxxx; Loic PALLARDY <loic.pallardy@xxxxxx>; s-
>>>>> anna@xxxxxx; peng.fan@xxxxxxx; Arnaud POULIQUEN
>>>>> <arnaud.pouliquen@xxxxxx>; Fabien DESSENNE
>>>>> <fabien.dessenne@xxxxxx>; linux-remoteproc@xxxxxxxxxxxxxxx
>>>>> Subject: [PATCH v2 16/17] remoteproc: Correctly deal with MCU
>>>>> synchronisation when changing state
>>>>>
>>>>> This patch deals with state changes when synchronising with an MCU. More
>>>>> specifically it prevents the MCU from being started if it already has been
>>>>> started by another entity. Similarly it prevents the AP from stopping the
>>>>> MCU if it hasn't been given the capability by platform firmware.
>>>>>
>>>>> Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>>>>> ---
>>>>> drivers/remoteproc/remoteproc_sysfs.c | 32
>>>>> ++++++++++++++++++++++++++-
>>>>> 1 file changed, 31 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/remoteproc/remoteproc_sysfs.c
>>>>> b/drivers/remoteproc/remoteproc_sysfs.c
>>>>> index 4956577ad4b4..741a3c152b82 100644
>>>>> --- a/drivers/remoteproc/remoteproc_sysfs.c
>>>>> +++ b/drivers/remoteproc/remoteproc_sysfs.c
>>>>> @@ -108,6 +108,29 @@ static ssize_t state_show(struct device *dev, struct
>>>>> device_attribute *attr,
>>>>> return sprintf(buf, "%s\n", rproc_state_string[state]);
>>>>> }
>>>>>
>>>>> +static int rproc_can_shutdown(struct rproc *rproc)
>>>>> +{
>>>>> + /* The MCU is not running, obviously an invalid operation. */
>>>>> + if (rproc->state != RPROC_RUNNING)
>>>>> + return false;
>>>>> +
>>>>> + /*
>>>>> + * The MCU is not running (see above) and the remoteproc core is
>>>>> the
>>>>> + * lifecycle manager, no problem calling for a shutdown.
>>>>> + */
>>>>> + if (!rproc_sync_with_mcu(rproc))
>>>>> + return true;
>>>>> +
>>>>> + /*
>>>>> + * The MCU has been loaded by another entity (see above) and the
>>>>> + * platform code has _not_ given us the capability of stopping it.
>>>>> + */
>>>>> + if (!rproc->sync_ops->stop)
>>>>> + return false;
>>>>
>>>> Test could be simplified
>>>> if (rproc_sync_with_mcu(rproc)) && !rproc->sync_ops->stop)
>>>> return false;
>>>
>>> I laid out the test individually on purpose. That way there is no coupling
>>> between conditions, it is plane to see what is going on and remains maintainable
>>> as we add new tests.
>>>
>>>>
>>>>> +
>>>>> + return true;
>>>>> +}
>>>>> +
>>>>> /* Change remote processor state via sysfs */
>>>>> static ssize_t state_store(struct device *dev,
>>>>> struct device_attribute *attr,
>>>>> @@ -120,11 +143,18 @@ static ssize_t state_store(struct device *dev,
>>>>> if (rproc->state == RPROC_RUNNING)
>>>>> return -EBUSY;
>>>>>
>>>>> + /*
>>>>> + * In synchronisation mode, booting the MCU is the
>>>>> + * responsibility of an external entity.
>>>>> + */
>>>>> + if (rproc_sync_with_mcu(rproc))
>>>>> + return -EINVAL;
>>>>> +
>>>> I don't understand this restriction, simply because it is preventing to resynchronize with a
>>>> coprocessor after a "stop".
>>
>> There's actually one more scenario even without "stop". If auto_boot is
>> set to false, then rproc_actuate will never get called.
>>
>>>> In the following configuration which can be configuration for coprocessor with romed/flashed
>>>> firmware (no reload needed):
>>>> on_init = true
>>>> after_stop = true
>>>> after_crash = true
>>>> Once you stop it via sysfs interface, you can't anymore restart/resync to it.
>>>
>>> Very true. The MCU will get restarted by another entity but the AP won't
>>> synchronise with it. I need more time to think about the best way to deal with
>>> this and may have to get back to you for further discussions.
>>>
>>>>
>>>> I think it will be better to modify rproc_boot() to take into account rproc_sync_with_mcu()
>>>> as below:
>>>>
>>>> int rproc_boot(struct rproc *rproc)
>>>> {
>>>> - const struct firmware *firmware_p;
>>>> + const struct firmware *firmware_p = NULL;
>>>> struct device *dev = &rproc->dev;
>>>> int ret;
>>>>
>>>> if (!rproc) {
>>>> pr_err("invalid rproc handle\n");
>>>> return -EINVAL;
>>>> }
>>>>
>>>> /* load firmware */
>>>> - ret = request_firmware(&firmware_p, rproc->firmware, dev);
>>>> - if (ret < 0) {
>>>> - dev_err(dev, "request_firmware failed: %d\n", ret);
>>>> - return ret;
>>>> + if (!rproc_sync_with_mcu(rproc)) {
>>
>> I guess this is what the original skip_fw_load was doing. And with the
>> current series, the userspace loading support usecase I have cannot be
>> achieved. If this is added back, I can try if that works for my usecases.
>
> I didn't notice this comment upon first read... Can you give me more details on
> what your usecase is order to see how best to deal with it?
We have a userspace loader usecase, where we use a daemon/server that
does the loading, and talks to the keystone remoteproc driver over a
character driver to publish the resource table and boot vectors, and to
start/stop the processor. You can find more details on the downstream
commit [1] we have. We exercise the regular kernel rproc state-machine
and suppress the firmware segment loading portion of it.
regards
Suman
[1]
https://git.ti.com/gitweb?p=rpmsg/remoteproc.git;a=commit;h=c41f591ccaaeef66bd4ccbb883ae72f6b0d173d7
>
> Thanks,
> Mathieu
>
>>
>>>> + ret = request_firmware(&firmware_p, rproc->firmware, dev);
>>>> + if (ret < 0) {
>>>> + dev_err(dev, "request_firmware failed: %d\n", ret);
>>>> + return ret;
>>>> + }
>>>> }
>>>>
>>>> ret = rproc_actuate(rproc, firmware_p);
>>>>
>>>> - release_firmware(firmware_p);
>>>> + if (firmware_p)
>>>> + release_firmware(firmware_p);
>>>>
>>>> return ret;
>>>> }
>>>>
>>>> Thanks to these modifications, I'm able to resync after a stop with coprocessor without reloading firmware.
>>>>
>>>>> ret = rproc_boot(rproc);
>>>>> if (ret)
>>>>> dev_err(&rproc->dev, "Boot failed: %d\n", ret);
>>>>> } else if (sysfs_streq(buf, "stop")) {
>>>>> - if (rproc->state != RPROC_RUNNING)
>>>>> + if (!rproc_can_shutdown(rproc))
>>>>> return -EINVAL;
>>>>>
>>>>> rproc_shutdown(rproc);
>>>> As rproc shutdown is also accessible as kernel API, I propose to move
>>>> rproc_can_shutdown() check inside rproc_shutdown() and to test
>>>> returned error
>>>
>>> Ah yes, it is public... As you point out, I think we'll need to move
>>> rproc_can_shutdown() in rproc_shutdown().
>>
>> I am assuming only the new conditions, right?
>>
>> regards
>> Suman
>>
>>>
>>> Thank you for taking the time to review this set,
>>> Mathieu
>>>
