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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Ionela Voinescu <ionela.voinescu@arm.com>,
	Kevin Wangtao <kevin.wangtao@hisilicon.com>,
	Leo Yan <leo.yan@linaro.org>,
	Jassi Brar <jaswinder.singh@linaro.org>
Cc: zhongkaihua@huawei.com, Dmitry Osipenko <digetx@gmail.com>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Rafael Wysocki <rjw@rjwysocki.net>,
	Sibi Sankar <sibis@codeaurora.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/13] opp: Keep track of currently programmed OPP
Date: Thu, 8 Jul 2021 13:23:53 +0530	[thread overview]
Message-ID: <20210708075353.ivsuc4y47i6bbhgz@vireshk-i7> (raw)
In-Reply-To: <20210707102410.GA4357@arm.com>

On 07-07-21, 11:24, Ionela Voinescu wrote:
> Now comes the interesting part: what seems to fix it is a call to
> clk_get_rate(opp_table->clk) in _set_opp(), which is what basically
> happened before this patch, as _find_current_opp() was always called.
> I do not need to do anything with the returned frequency.

Wow, thanks for narrowing it down this far :)

I had a quick look and this is what I think is the problem here.

This platform uses mailbox API to send its frequency change requests to another
processor.  And the way it is written currently, I don't see any guarantee
whatsoever which say

  "once clk_set_rate() returns, the frequency would have already changed".

And this may exactly be the thing you are able to hit, luckily because of this
patchset :)

As a quick way of checking if that is right or not, this may make it work:

diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
index 395ddc250828..9856c1c84dcf 100644
--- a/drivers/mailbox/hi3660-mailbox.c
+++ b/drivers/mailbox/hi3660-mailbox.c
@@ -201,6 +201,9 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)

        /* Trigger data transferring */
        writel(BIT(mchan->ack_irq), base + MBOX_SEND_REG);
+
+       hi3660_mbox_check_state(chan);
+
        return 0;
 }

-------------------------8<-------------------------

As a proper fix, something like this (not even compile tested) is required I
believe as I don't see the clients would know if the transfer is over. Cc'ing
mailbox guys to see what can be done.

diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
index 3a653d54bee0..c1e62ea4cf01 100644
--- a/drivers/clk/hisilicon/clk-hi3660-stub.c
+++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
@@ -89,7 +89,6 @@ static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
                stub_clk->msg[0], stub_clk->msg[1]);
 
        mbox_send_message(stub_clk_chan.mbox, stub_clk->msg);
-       mbox_client_txdone(stub_clk_chan.mbox, 0);
 
        stub_clk->rate = rate;
        return 0;
@@ -131,7 +130,7 @@ static int hi3660_stub_clk_probe(struct platform_device *pdev)
        /* Use mailbox client without blocking */
        stub_clk_chan.cl.dev = dev;
        stub_clk_chan.cl.tx_done = NULL;
-       stub_clk_chan.cl.tx_block = false;
+       stub_clk_chan.cl.tx_block = true;
        stub_clk_chan.cl.knows_txdone = false;
 
        /* Allocate mailbox channel */
diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
index 395ddc250828..8f6b787c0aba 100644
--- a/drivers/mailbox/hi3660-mailbox.c
+++ b/drivers/mailbox/hi3660-mailbox.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-// Copyright (c) 2017-2018 HiSilicon Limited.
+// Copyright (c) 2017-2018 Hisilicon Limited.
 // Copyright (c) 2017-2018 Linaro Limited.
 
 #include <linux/bitops.h>
@@ -83,7 +83,7 @@ static struct hi3660_mbox *to_hi3660_mbox(struct mbox_controller *mbox)
        return container_of(mbox, struct hi3660_mbox, controller);
 }
 
-static int hi3660_mbox_check_state(struct mbox_chan *chan)
+static bool hi3660_mbox_last_tx_done(struct mbox_chan *chan)
 {
        unsigned long ch = (unsigned long)chan->con_priv;
        struct hi3660_mbox *mbox = to_hi3660_mbox(chan->mbox);
@@ -94,20 +94,20 @@ static int hi3660_mbox_check_state(struct mbox_chan *chan)
 
        /* Mailbox is ready to use */
        if (readl(base + MBOX_MODE_REG) & MBOX_STATE_READY)
-               return 0;
+               return true;
 
        /* Wait for acknowledge from remote */
        ret = readx_poll_timeout_atomic(readl, base + MBOX_MODE_REG,
                        val, (val & MBOX_STATE_ACK), 1000, 300000);
        if (ret) {
                dev_err(mbox->dev, "%s: timeout for receiving ack\n", __func__);
-               return ret;
+               return false;
        }
 
        /* clear ack state, mailbox will get back to ready state */
        writel(BIT(mchan->ack_irq), base + MBOX_ICLR_REG);
 
-       return 0;
+       return true;
 }
 
 static int hi3660_mbox_unlock(struct mbox_chan *chan)
@@ -182,10 +182,6 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
        unsigned int i;
        int ret;
 
-       ret = hi3660_mbox_check_state(chan);
-       if (ret)
-               return ret;
-
        /* Clear mask for destination interrupt */
        writel_relaxed(~BIT(mchan->dst_irq), base + MBOX_IMASK_REG);
 
@@ -207,6 +203,7 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
 static const struct mbox_chan_ops hi3660_mbox_ops = {
        .startup        = hi3660_mbox_startup,
        .send_data      = hi3660_mbox_send_data,
+       .last_tx_done   = hi3660_mbox_last_tx_done,
 };
 
 static struct mbox_chan *hi3660_mbox_xlate(struct mbox_controller *controller,
@@ -259,6 +256,7 @@ static int hi3660_mbox_probe(struct platform_device *pdev)
        mbox->controller.num_chans = MBOX_CHAN_MAX;
        mbox->controller.ops = &hi3660_mbox_ops;
        mbox->controller.of_xlate = hi3660_mbox_xlate;
+       mbox->controller.txdone_poll = true;
 
        /* Initialize mailbox channel data */
        chan = mbox->chan;

-- 
viresh

WARNING: multiple messages have this Message-ID
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Ionela Voinescu <ionela.voinescu@arm.com>,
	Kevin Wangtao <kevin.wangtao@hisilicon.com>,
	Leo Yan <leo.yan@linaro.org>,
	Jassi Brar <jaswinder.singh@linaro.org>
Cc: zhongkaihua@huawei.com, Dmitry Osipenko <digetx@gmail.com>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	linux-pm@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Rafael Wysocki <rjw@rjwysocki.net>,
	Sibi Sankar <sibis@codeaurora.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/13] opp: Keep track of currently programmed OPP
Date: Thu, 8 Jul 2021 13:23:53 +0530	[thread overview]
Message-ID: <20210708075353.ivsuc4y47i6bbhgz@vireshk-i7> (raw)
In-Reply-To: <20210707102410.GA4357@arm.com>

On 07-07-21, 11:24, Ionela Voinescu wrote:
> Now comes the interesting part: what seems to fix it is a call to
> clk_get_rate(opp_table->clk) in _set_opp(), which is what basically
> happened before this patch, as _find_current_opp() was always called.
> I do not need to do anything with the returned frequency.

Wow, thanks for narrowing it down this far :)

I had a quick look and this is what I think is the problem here.

This platform uses mailbox API to send its frequency change requests to another
processor.  And the way it is written currently, I don't see any guarantee
whatsoever which say

  "once clk_set_rate() returns, the frequency would have already changed".

And this may exactly be the thing you are able to hit, luckily because of this
patchset :)

As a quick way of checking if that is right or not, this may make it work:

diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
index 395ddc250828..9856c1c84dcf 100644
--- a/drivers/mailbox/hi3660-mailbox.c
+++ b/drivers/mailbox/hi3660-mailbox.c
@@ -201,6 +201,9 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)

        /* Trigger data transferring */
        writel(BIT(mchan->ack_irq), base + MBOX_SEND_REG);
+
+       hi3660_mbox_check_state(chan);
+
        return 0;
 }

-------------------------8<-------------------------

As a proper fix, something like this (not even compile tested) is required I
believe as I don't see the clients would know if the transfer is over. Cc'ing
mailbox guys to see what can be done.

diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
index 3a653d54bee0..c1e62ea4cf01 100644
--- a/drivers/clk/hisilicon/clk-hi3660-stub.c
+++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
@@ -89,7 +89,6 @@ static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
                stub_clk->msg[0], stub_clk->msg[1]);
 
        mbox_send_message(stub_clk_chan.mbox, stub_clk->msg);
-       mbox_client_txdone(stub_clk_chan.mbox, 0);
 
        stub_clk->rate = rate;
        return 0;
@@ -131,7 +130,7 @@ static int hi3660_stub_clk_probe(struct platform_device *pdev)
        /* Use mailbox client without blocking */
        stub_clk_chan.cl.dev = dev;
        stub_clk_chan.cl.tx_done = NULL;
-       stub_clk_chan.cl.tx_block = false;
+       stub_clk_chan.cl.tx_block = true;
        stub_clk_chan.cl.knows_txdone = false;
 
        /* Allocate mailbox channel */
diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
index 395ddc250828..8f6b787c0aba 100644
--- a/drivers/mailbox/hi3660-mailbox.c
+++ b/drivers/mailbox/hi3660-mailbox.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-// Copyright (c) 2017-2018 HiSilicon Limited.
+// Copyright (c) 2017-2018 Hisilicon Limited.
 // Copyright (c) 2017-2018 Linaro Limited.
 
 #include <linux/bitops.h>
@@ -83,7 +83,7 @@ static struct hi3660_mbox *to_hi3660_mbox(struct mbox_controller *mbox)
        return container_of(mbox, struct hi3660_mbox, controller);
 }
 
-static int hi3660_mbox_check_state(struct mbox_chan *chan)
+static bool hi3660_mbox_last_tx_done(struct mbox_chan *chan)
 {
        unsigned long ch = (unsigned long)chan->con_priv;
        struct hi3660_mbox *mbox = to_hi3660_mbox(chan->mbox);
@@ -94,20 +94,20 @@ static int hi3660_mbox_check_state(struct mbox_chan *chan)
 
        /* Mailbox is ready to use */
        if (readl(base + MBOX_MODE_REG) & MBOX_STATE_READY)
-               return 0;
+               return true;
 
        /* Wait for acknowledge from remote */
        ret = readx_poll_timeout_atomic(readl, base + MBOX_MODE_REG,
                        val, (val & MBOX_STATE_ACK), 1000, 300000);
        if (ret) {
                dev_err(mbox->dev, "%s: timeout for receiving ack\n", __func__);
-               return ret;
+               return false;
        }
 
        /* clear ack state, mailbox will get back to ready state */
        writel(BIT(mchan->ack_irq), base + MBOX_ICLR_REG);
 
-       return 0;
+       return true;
 }
 
 static int hi3660_mbox_unlock(struct mbox_chan *chan)
@@ -182,10 +182,6 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
        unsigned int i;
        int ret;
 
-       ret = hi3660_mbox_check_state(chan);
-       if (ret)
-               return ret;
-
        /* Clear mask for destination interrupt */
        writel_relaxed(~BIT(mchan->dst_irq), base + MBOX_IMASK_REG);
 
@@ -207,6 +203,7 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
 static const struct mbox_chan_ops hi3660_mbox_ops = {
        .startup        = hi3660_mbox_startup,
        .send_data      = hi3660_mbox_send_data,
+       .last_tx_done   = hi3660_mbox_last_tx_done,
 };
 
 static struct mbox_chan *hi3660_mbox_xlate(struct mbox_controller *controller,
@@ -259,6 +256,7 @@ static int hi3660_mbox_probe(struct platform_device *pdev)
        mbox->controller.num_chans = MBOX_CHAN_MAX;
        mbox->controller.ops = &hi3660_mbox_ops;
        mbox->controller.of_xlate = hi3660_mbox_xlate;
+       mbox->controller.txdone_poll = true;
 
        /* Initialize mailbox channel data */
        chan = mbox->chan;

-- 
viresh

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  reply	other threads:[~2021-07-08  7:53 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21 11:17 [PATCH 00/13] opp: Implement dev_pm_opp_set_opp() Viresh Kumar
2021-01-21 11:17 ` Viresh Kumar
2021-01-21 11:17 ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 01/13] opp: Rename _opp_set_rate_zero() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 02/13] opp: No need to check clk for errors Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 03/13] opp: Keep track of currently programmed OPP Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 21:41   ` Dmitry Osipenko
2021-01-21 21:41     ` Dmitry Osipenko
2021-01-22  4:45     ` Viresh Kumar
2021-01-22  4:45       ` Viresh Kumar
2021-01-22 14:31       ` Dmitry Osipenko
2021-01-22 14:31         ` Dmitry Osipenko
2021-01-25  3:12         ` Viresh Kumar
2021-01-25  3:12           ` Viresh Kumar
2021-01-27 16:31       ` Akhil P Oommen
2021-01-28  4:14         ` Viresh Kumar
2021-01-28  4:14           ` Viresh Kumar
2021-07-07 10:24   ` Ionela Voinescu
2021-07-07 10:24     ` Ionela Voinescu
2021-07-08  7:53     ` Viresh Kumar [this message]
2021-07-08  7:53       ` Viresh Kumar
2021-07-09  8:57       ` Ionela Voinescu
2021-07-09  8:57         ` Ionela Voinescu
2021-07-12  4:14         ` Viresh Kumar
2021-07-12  4:14           ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 04/13] opp: Split _set_opp() out of dev_pm_opp_set_rate() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 05/13] opp: Allow _set_opp() to work for non-freq devices Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 06/13] opp: Allow _generic_set_opp_regulator() " Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 07/13] opp: Allow _generic_set_opp_clk_only() " Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 20:26   ` Dmitry Osipenko
2021-01-21 20:26     ` Dmitry Osipenko
2021-01-22  4:35     ` Viresh Kumar
2021-01-22  4:35       ` Viresh Kumar
2021-01-25 21:09       ` Dmitry Osipenko
2021-01-25 21:09         ` Dmitry Osipenko
2021-01-27  6:58         ` Viresh Kumar
2021-01-27  6:58           ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 08/13] opp: Update parameters of _set_opp_custom() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 09/13] opp: Implement dev_pm_opp_set_opp() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 10/13] cpufreq: qcom: Migrate to dev_pm_opp_set_opp() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 11/13] devfreq: tegra30: " Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 21:36   ` Dmitry Osipenko
2021-01-21 21:36     ` Dmitry Osipenko
2021-01-22  6:26     ` Viresh Kumar
2021-01-22  6:26       ` Viresh Kumar
2021-01-22 15:28       ` Dmitry Osipenko
2021-01-22 15:28         ` Dmitry Osipenko
2021-01-25  3:14         ` Viresh Kumar
2021-01-25  3:14           ` Viresh Kumar
2021-01-25 16:00           ` Dmitry Osipenko
2021-01-25 16:00             ` Dmitry Osipenko
2021-01-27  9:10   ` [PATCH V2 " Viresh Kumar
2021-01-27 10:02     ` Viresh Kumar
2021-01-27 15:58       ` Dmitry Osipenko
2021-01-28  7:01         ` Viresh Kumar
2021-02-01  0:21     ` Chanwoo Choi
2021-02-01 19:57     ` Dmitry Osipenko
2021-01-21 11:17 ` [PATCH 12/13] drm: msm: " Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar
2021-01-21 11:17 ` [PATCH 13/13] opp: Remove dev_pm_opp_set_bw() Viresh Kumar
2021-01-21 11:17   ` Viresh Kumar

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