From: Suman Anna <s-anna@ti.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Loic PALLARDY <loic.pallardy@st.com>,
"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
"ohad@wizery.com" <ohad@wizery.com>,
"peng.fan@nxp.com" <peng.fan@nxp.com>,
Arnaud POULIQUEN <arnaud.pouliquen@st.com>,
Fabien DESSENNE <fabien.dessenne@st.com>,
"linux-remoteproc@vger.kernel.org"
<linux-remoteproc@vger.kernel.org>
Subject: Re: [PATCH v2 16/17] remoteproc: Correctly deal with MCU synchronisation when changing state
Date: Thu, 9 Apr 2020 15:40:20 -0500 [thread overview]
Message-ID: <3240a2b3-094d-fb05-e8e9-500f9fe8466d@ti.com> (raw)
In-Reply-To: <20200402204231.GC9160@xps15>
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@linaro.org>
>>>>> Sent: mardi 24 mars 2020 22:46
>>>>> To: bjorn.andersson@linaro.org
>>>>> Cc: ohad@wizery.com; Loic PALLARDY <loic.pallardy@st.com>; s-
>>>>> anna@ti.com; peng.fan@nxp.com; Arnaud POULIQUEN
>>>>> <arnaud.pouliquen@st.com>; Fabien DESSENNE
>>>>> <fabien.dessenne@st.com>; linux-remoteproc@vger.kernel.org
>>>>> 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@linaro.org>
>>>>> ---
>>>>> 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
>>>
next prev parent reply other threads:[~2020-04-09 20:40 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 21:45 [PATCH v2 00/17] remoteproc: Add support for synchronisation with MCU Mathieu Poirier
2020-03-24 21:45 ` [PATCH v2 01/17] remoteproc: Add new operation and state machine for MCU synchronisation Mathieu Poirier
2020-03-30 22:46 ` Suman Anna
2020-03-30 22:49 ` Suman Anna
2020-04-01 21:53 ` Mathieu Poirier
2020-04-09 21:38 ` Suman Anna
2020-04-09 21:38 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 02/17] remoteproc: Introduce function rproc_set_mcu_sync_state() Mathieu Poirier
2020-03-30 22:55 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 03/17] remoteproc: Split firmware name allocation from rproc_alloc() Mathieu Poirier
2020-03-27 11:05 ` Loic PALLARDY
2020-03-30 19:47 ` Suman Anna
2020-04-01 21:58 ` Mathieu Poirier
2020-03-24 21:45 ` [PATCH v2 04/17] remoteproc: Split rproc_ops " Mathieu Poirier
2020-03-30 19:54 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 05/17] remoteproc: Get rid of tedious error path Mathieu Poirier
2020-03-30 20:31 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 06/17] remoteproc: Introduce function rproc_alloc_internals() Mathieu Poirier
2020-03-27 11:10 ` Loic PALLARDY
2020-03-30 20:38 ` Suman Anna
2020-04-01 20:29 ` Mathieu Poirier
2020-04-09 21:53 ` Suman Anna
2020-04-09 21:53 ` Suman Anna
2020-03-30 23:07 ` Mathieu Poirier
2020-03-24 21:45 ` [PATCH v2 07/17] remoteproc: Introduce function rproc_alloc_state_machine() Mathieu Poirier
2020-03-27 13:12 ` Loic PALLARDY
2020-03-30 23:10 ` Suman Anna
2020-04-01 20:41 ` Mathieu Poirier
2020-04-09 18:35 ` Suman Anna
2020-04-09 18:35 ` Suman Anna
2020-03-30 23:13 ` Mathieu Poirier
2020-03-24 21:45 ` [PATCH v2 08/17] remoteproc: Allocate synchronisation state machine Mathieu Poirier
2020-03-27 13:47 ` Loic PALLARDY
2020-03-30 23:16 ` Mathieu Poirier
2020-03-30 23:20 ` Suman Anna
2020-04-01 20:46 ` Mathieu Poirier
2020-03-24 21:45 ` [PATCH v2 09/17] remoteproc: Call the right core function based on synchronisation state Mathieu Poirier
2020-03-31 15:10 ` Suman Anna
2020-04-02 20:16 ` Mathieu Poirier
2020-04-09 18:48 ` Suman Anna
2020-04-09 18:48 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 10/17] remoteproc: Decouple firmware load and remoteproc booting Mathieu Poirier
2020-03-31 21:27 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 11/17] remoteproc: Repurpose function rproc_trigger_auto_boot() Mathieu Poirier
2020-03-31 21:32 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 12/17] remoteproc: Rename function rproc_fw_boot() Mathieu Poirier
2020-03-31 21:42 ` Suman Anna
2020-03-24 21:45 ` [PATCH v2 13/17] remoteproc: Introducting new functions to start and stop an MCU Mathieu Poirier
2020-03-31 18:08 ` Suman Anna
2020-03-31 21:46 ` Suman Anna
2020-04-01 21:55 ` Mathieu Poirier
2020-03-24 21:46 ` [PATCH v2 14/17] remoteproc: Refactor function rproc_trigger_recovery() Mathieu Poirier
2020-03-31 21:52 ` Suman Anna
2020-04-02 20:35 ` Mathieu Poirier
2020-04-09 19:02 ` Suman Anna
2020-04-09 19:02 ` Suman Anna
2020-03-24 21:46 ` [PATCH v2 15/17] remoteproc: Correctly deal with MCU synchronisation when changing FW image Mathieu Poirier
2020-03-27 13:50 ` Loic PALLARDY
2020-03-30 23:21 ` Mathieu Poirier
2020-03-31 22:14 ` Suman Anna
2020-04-01 20:55 ` Mathieu Poirier
2020-04-22 21:29 ` Mathieu Poirier
2020-04-22 21:29 ` Mathieu Poirier
2020-04-22 22:56 ` Suman Anna
2020-04-22 22:56 ` Suman Anna
2020-03-24 21:46 ` [PATCH v2 16/17] remoteproc: Correctly deal with MCU synchronisation when changing state Mathieu Poirier
2020-03-27 14:04 ` Loic PALLARDY
2020-03-30 23:49 ` Mathieu Poirier
2020-03-31 22:35 ` Suman Anna
2020-04-01 21:29 ` Mathieu Poirier
2020-04-09 20:55 ` Suman Anna
2020-04-09 20:55 ` Suman Anna
2020-04-02 20:42 ` Mathieu Poirier
2020-04-09 20:40 ` Suman Anna [this message]
2020-04-09 20:40 ` Suman Anna
2020-03-24 21:46 ` [PATCH v2 17/17] remoteproc: Make MCU synchronisation state changes on stop and crashed Mathieu Poirier
2020-03-27 17:20 ` [PATCH v2 00/17] remoteproc: Add support for synchronisation with MCU Loic PALLARDY
2020-03-31 22:51 ` Suman Anna
2020-04-01 21:39 ` Mathieu Poirier
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