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Message-ID: <73d5ee87-5985-4880-aefb-449eac3ee149@bootlin.com>
Date: Mon, 1 Jul 2024 18:49:40 +0200
From: Richard GENOUD <richard.genoud@...tlin.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
Philipp Zabel <p.zabel@...gutronix.de>, Suman Anna <s-anna@...com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Udit Kumar <u-kumar1@...com>, Thomas Richard <thomas.richard@...tlin.com>,
Gregory CLEMENT <gregory.clement@...tlin.com>, Hari Nagalla
<hnagalla@...com>, Théo Lebrun <theo.lebrun@...tlin.com>,
linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] remoteproc: k3-r5: k3_r5_rproc_stop: code reorder
Le 01/07/2024 à 18:35, Mathieu Poirier a écrit :
> On Mon, Jul 01, 2024 at 10:03:22AM +0200, Richard GENOUD wrote:
>> Le 28/06/2024 à 23:18, Mathieu Poirier a écrit :
>>> On Fri, Jun 21, 2024 at 05:00:57PM +0200, Richard Genoud wrote:
>>>> In the next commit, a RP_MBOX_SHUTDOWN message will be sent in
>>>> k3_r5_rproc_stop() to the remote proc (in lockstep on not)
>>>> Thus, the sanity check "do not allow core 0 to stop before core 1"
>>>> should be moved at the beginning of the function so that the generic case
>>>> can be dealt with.
>>>>
>>>> In order to have an easier patch to review, those actions are broke in
>>>> two patches:
>>>> - this patch: moving the sanity check at the beginning (No functional
>>>> change).
>>>> - next patch: doing the real job (sending shutdown messages to remote
>>>> procs before halting them).
>>>>
>>>> Basically, we had:
>>>> - cluster_mode actions
>>>> - !cluster_mode sanity check
>>>> - !cluster_mode actions
>>>> And now:
>>>> - !cluster_mode sanity check
>>>> - cluster_mode actions
>>>> - !cluster_mode actions
>>>>
>>>> Signed-off-by: Richard Genoud <richard.genoud@...tlin.com>
>>>> ---
>>>> drivers/remoteproc/ti_k3_r5_remoteproc.c | 24 ++++++++++++++----------
>>>> 1 file changed, 14 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>>>> index 1f18b08618c8..a2ead87952c7 100644
>>>> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>>>> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>>>> @@ -636,16 +636,8 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>>>> struct k3_r5_core *core1, *core = kproc->core;
>>>> int ret;
>>>> - /* halt all applicable cores */
>>>> - if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
>>>> - list_for_each_entry(core, &cluster->cores, elem) {
>>>> - ret = k3_r5_core_halt(core);
>>>> - if (ret) {
>>>> - core = list_prev_entry(core, elem);
>>>> - goto unroll_core_halt;
>>>> - }
>>>> - }
>>>> - } else {
>>>> +
>>>> + if (cluster->mode != CLUSTER_MODE_LOCKSTEP) {
>>>> /* do not allow core 0 to stop before core 1 */
>>>> core1 = list_last_entry(&cluster->cores, struct k3_r5_core,
>>>> elem);
>>>> @@ -656,6 +648,18 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>>>> ret = -EPERM;
>>>> goto out;
>>>> }
>>>> + }
>>>> +
>>>> + /* halt all applicable cores */
>>>> + if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
>>>> + list_for_each_entry(core, &cluster->cores, elem) {
>>>> + ret = k3_r5_core_halt(core);
>>>> + if (ret) {
>>>> + core = list_prev_entry(core, elem);
>>>> + goto unroll_core_halt;
>>>> + }
>>>> + }
>>>> + } else {
>>>> ret = k3_r5_core_halt(core);
>>>> if (ret)
>>>
>>> With this patch, the "else" in this "if" condition is coupled with the "if" from
>>> the lockstep mode, making the code extremaly hard to read. The original code
>>> has a k3_r5_core_halt() in both "if" conditions, making the condition
>>> independent from one another.
>>>
>> I'm not sure I understand what you mean.
>
> With your patch applied I get the following: https://pastebin.com/yTZ0pKcS
>
> Let's say the R5 is in split mode and k3_r5_rproc_stop() called on core1. The
> if() that deal with that condition is on line 10, while the function that halts
> the remote processor is online 34, part of the else clause that handles lockstep
> mode. The two if() clauses are entangled and nothing good can come out of that.
Ok, I see your point now.
Thanks !
>
>> Anyway, I'm not happy with this diff, it doesn't reflect what was intended.
>> (which is moving the check "core 0 should not be stop before core 1" at the beginning)
>>
>> Tweaking around with the diff algorithms, I came with something way easier to read I think:
>>
>> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> index 1f18b08618c8..a2ead87952c7 100644
>> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> @@ -636,6 +636,20 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>> struct k3_r5_core *core1, *core = kproc->core;
>> int ret;
>> +
>> + if (cluster->mode != CLUSTER_MODE_LOCKSTEP) {
>> + /* do not allow core 0 to stop before core 1 */
>> + core1 = list_last_entry(&cluster->cores, struct k3_r5_core,
>> + elem);
>> + if (core != core1 && core1->rproc->state != RPROC_OFFLINE &&
>> + core1->rproc->state != RPROC_SUSPENDED) {
>> + dev_err(dev, "%s: can not stop core 0 before core 1\n",
>> + __func__);
>> + ret = -EPERM;
>> + goto out;
>> + }
>> + }
>> +
>> /* halt all applicable cores */
>> if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
>> list_for_each_entry(core, &cluster->cores, elem) {
>> @@ -646,16 +660,6 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>> }
>> }
>> } else {
>> - /* do not allow core 0 to stop before core 1 */
>> - core1 = list_last_entry(&cluster->cores, struct k3_r5_core,
>> - elem);
>> - if (core != core1 && core1->rproc->state != RPROC_OFFLINE &&
>> - core1->rproc->state != RPROC_SUSPENDED) {
>> - dev_err(dev, "%s: can not stop core 0 before core 1\n",
>> - __func__);
>> - ret = -EPERM;
>> - goto out;
>> - }
>> ret = k3_r5_core_halt(core);
>> if (ret)
>>
>>
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