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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: Kevin Wangtao <kevin.wangtao@hisilicon.com>,
	Leo Yan <leo.yan@linaro.org>,
	Jassi Brar <jaswinder.singh@linaro.org>,
	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: Mon, 12 Jul 2021 09:44:08 +0530	[thread overview]
Message-ID: <20210712041408.5dgtwcp55pgt7twn@vireshk-i7> (raw)
In-Reply-To: <20210709085704.GA10180@arm.com>

On 09-07-21, 09:57, Ionela Voinescu wrote:
> On Thursday 08 Jul 2021 at 13:23:53 (+0530), Viresh Kumar wrote:
> > 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".
> > 
> 
> I think what was strange to me was that the frequency never seems to
> change, there isn't just a delay in the new frequency taking effect, as
> I would expect in these cases. Or if there is a delay, that's quite large
> - at least a second.

No idea on what the firmware is doing behind the scene :)

> > 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);
> > +
> 
> I gave this a try an it does work for me.

Good, so that kind of proves what I was suspecting. The mailbox driver looks
buggy here.

> > -------------------------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.
> > 
> 
> I'll give this a try as well when there is consensus. I might even try to
> review it, if the time allows.

Sure, lets see what the platform guys think about this first.

Kevin, Kaihua ?

-- 
viresh

WARNING: multiple messages have this Message-ID
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: Kevin Wangtao <kevin.wangtao@hisilicon.com>,
	Leo Yan <leo.yan@linaro.org>,
	Jassi Brar <jaswinder.singh@linaro.org>,
	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: Mon, 12 Jul 2021 09:44:08 +0530	[thread overview]
Message-ID: <20210712041408.5dgtwcp55pgt7twn@vireshk-i7> (raw)
In-Reply-To: <20210709085704.GA10180@arm.com>

On 09-07-21, 09:57, Ionela Voinescu wrote:
> On Thursday 08 Jul 2021 at 13:23:53 (+0530), Viresh Kumar wrote:
> > 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".
> > 
> 
> I think what was strange to me was that the frequency never seems to
> change, there isn't just a delay in the new frequency taking effect, as
> I would expect in these cases. Or if there is a delay, that's quite large
> - at least a second.

No idea on what the firmware is doing behind the scene :)

> > 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);
> > +
> 
> I gave this a try an it does work for me.

Good, so that kind of proves what I was suspecting. The mailbox driver looks
buggy here.

> > -------------------------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.
> > 
> 
> I'll give this a try as well when there is consensus. I might even try to
> review it, if the time allows.

Sure, lets see what the platform guys think about this first.

Kevin, Kaihua ?

-- 
viresh

_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-07-12  4:14 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
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 [this message]
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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