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SubjectRe: [Patch v6 4/7] slimbus: Add support for 'clock-pause' feature
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Thanks for the review comments



On 07/10/17 09:06, Jonathan Neuschäfer wrote:
> Hi, some trivial comments below.
>
> On Fri, Oct 06, 2017 at 05:51:33PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> Per slimbus specification, a reconfiguration sequence known as
>> 'clock pause' needs to be broadcast over the bus while entering low-
>> power mode. Clock-pause is initiated by the controller driver.
>> To exit clock-pause, controller typically wakes up the framer device.
>> Since wakeup precedure is controller-specific, framework calls it via
>> controller's function pointer to invoke it.
>>
>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
> [...]
>> @@ -429,6 +444,14 @@ void slim_return_tx(struct slim_controller *ctrl, int err)
>> cur.cb(cur.ctx, err);
>>
>> up(&ctrl->tx_sem);
>> + if (!cur.clk_pause && (!cur.need_tid || err)) {
>> + /**
>
> This isn't really a kerneldoc comment.
Will fix all such instances in next version.
>
>> + * remove runtime-pm vote if this was TX only, or
>> + * if there was error during this transaction
>> + */
>> + pm_runtime_mark_last_busy(ctrl->dev.parent);
>> + pm_runtime_put_autosuspend(ctrl->dev.parent);
>> + }
>> }
>> EXPORT_SYMBOL_GPL(slim_return_tx);
>>
> [...]
>> +/**
>> + * slim_ctrl_clk_pause: Called by slimbus controller to enter/exit 'clock pause'
>> + * Slimbus specification needs this sequence to turn-off clocks for the bus.
>> + * The sequence involves sending 3 broadcast messages (reconfiguration
>> + * sequence) to inform all devices on the bus.
>> + * To exit clock-pause, controller typically wakes up active framer device.
>> + * @ctrl: controller requesting bus to be paused or woken up
>> + * @wakeup: Wakeup this controller from clock pause.
>> + * @restart: Restart time value per spec used for clock pause. This value
>> + * isn't used when controller is to be woken up.
>> + * This API executes clock pause reconfiguration sequence if wakeup is false.
>> + * If wakeup is true, controller's wakeup is called.
>> + * For entering clock-pause, -EBUSY is returned if a message txn in pending.
>> + */
>> +int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart)
>> +{
>> + int i, ret = 0;
>> + unsigned long flags;
>> + struct slim_sched *sched = &ctrl->sched;
>> + struct slim_val_inf msg = {0, 0, NULL, NULL, NULL, NULL};
>> +
>> + DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION,
>> + 3, SLIM_LA_MANAGER, &msg);
>> +
>> + if (wakeup == false && restart > SLIM_CLK_UNSPECIFIED)
>> + return -EINVAL;
>> +
>> + mutex_lock(&sched->m_reconf);
>> + if (wakeup) {
>> + if (sched->clk_state == SLIM_CLK_ACTIVE) {
>> + mutex_unlock(&sched->m_reconf);
>> + return 0;
>> + }
>> +
>> + /**
>
> ditto
>
>> + * Fine-tune calculation based on clock gear,
>> + * message-bandwidth after bandwidth management
>> + */
>> + ret = wait_for_completion_timeout(&sched->pause_comp,
>> + msecs_to_jiffies(100));
>> + if (!ret) {
>> + mutex_unlock(&sched->m_reconf);
>> + pr_err("Previous clock pause did not finish");
>> + return -ETIMEDOUT;
>> + }
>> + ret = 0;
>> +
>> + /**
>
> ditto
>
>> + * Slimbus framework will call controller wakeup
>> + * Controller should make sure that it sets active framer
>> + * out of clock pause
>> + */
>> + if (sched->clk_state == SLIM_CLK_PAUSED && ctrl->wakeup)
>> + ret = ctrl->wakeup(ctrl);
>> + if (!ret)
>> + sched->clk_state = SLIM_CLK_ACTIVE;
>> + mutex_unlock(&sched->m_reconf);
>> +
>> + return ret;
>> + }
> [...]
>
>
> Thanks,
> Jonathan Neuschäfer
>

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