From: Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>
Cc: robh+dt@kernel.org, mark.rutland@arm.com, andy.gross@linaro.org,
david.brown@linaro.org, sboyd@kernel.org, will.deacon@arm.com,
mturquette@baylibre.com, jassisinghbrar@gmail.com,
vkoul@kernel.org, niklas.cassel@linaro.org, sibis@codeaurora.org,
georgi.djakov@linaro.org, arnd@arndb.de,
horms+renesas@verge.net.au, heiko@sntech.de,
enric.balletbo@collabora.com, jagan@amarulasolutions.com,
olof@lixom.net, amit.kucheria@linaro.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org
Subject: Re: [PATCH 08/13] clk: qcom: hfpll: CLK_IGNORE_UNUSED
Date: Thu, 17 Jan 2019 09:38:16 +0100 [thread overview]
Message-ID: <9abbe59b-433c-4e30-1e4d-b5eed3afc695@linaro.org> (raw)
In-Reply-To: <20190117063312.GE25498@builder>
On 1/17/19 07:33, Bjorn Andersson wrote:
> On Mon 17 Dec 01:46 PST 2018, Jorge Ramirez-Ortiz wrote:
>
>> When COMMON_CLK_DISABLED_UNUSED is set, in an effort to save power and
>> to keep the software model of the clock in line with reality, the
>> framework transverses the clock tree and disables those clocks that
>> were enabled by the firmware but have not been enabled by any device
>> driver.
>>
>> If CPUFREQ is enabled, early during the system boot, it might attempt
>> to change the CPU frequency ("set_rate"). If the HFPLL is selected as
>> a provider, it will then change the rate for this clock.
>>
>> As boot continues, clk_disable_unused_subtree will run. Since it wont
>> find a valid counter (enable_count) for a clock that is actually
>> enabled it will attempt to disable it which will cause the CPU to
>> stop. Notice that in this driver, calls to check whether the clock is
>> enabled are routed via the is_enabled callback which queries the
>> hardware.
>>
>
> With the CPUFREQ referencing the CPU clock driver, that has decided to
> run off this clock, why is it not refcounted?
COMMON_CLK_DISABLED_UNUSED relies on the enable_count reference counter
to disable the clocks that were enabled by the firwmare and not by the
drivers.
the cpufreq driver does not enable the cpu clock.
so when clk_change_rate is called, the enable_count counter is not
incremented and therefore it just remains null since this was enabled by
the firmware.
I tried doing:
diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index e58bfcb..5a9f83e 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -124,6 +124,10 @@ static int resources_available(void)
return ret;
}
+ ret = clk_prepare_enable(cpu_clk);
+ if (ret)
+ return ret;
+
clk_put(cpu_clk);
name = find_supply_name(cpu_dev);
and that removed the need for CLK_IGNORE_UNUSED. But I am not sure of
the system wide consequences of that change to cpufreq.
maybe Viresh can comment?
>
> Regards,
> Bjorn
>
>> The following commit, rather than marking the clock critical and
>> forcing the clock to be always enabled, addresses the above scenario
>> making sure the clock is not disabled but it continues to rely on the
>> firmware to enable the clock.
>>
>> Co-developed-by: Niklas Cassel <niklas.cassel@linaro.org>
>> Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
>> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
>> ---
>> drivers/clk/qcom/hfpll.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/clk/qcom/hfpll.c b/drivers/clk/qcom/hfpll.c
>> index 0ffed0d..9d92f5d 100644
>> --- a/drivers/clk/qcom/hfpll.c
>> +++ b/drivers/clk/qcom/hfpll.c
>> @@ -58,6 +58,7 @@ static int qcom_hfpll_probe(struct platform_device *pdev)
>> .parent_names = (const char *[]){ "xo" },
>> .num_parents = 1,
>> .ops = &clk_ops_hfpll,
>> + .flags = CLK_IGNORE_UNUSED,
>> };
>>
>> h = devm_kzalloc(dev, sizeof(*h), GFP_KERNEL);
>> --
>> 2.7.4
>>
>
next prev parent reply other threads:[~2019-01-17 8:38 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 9:46 [PATCH 00/13] Support CPU frequency scaling on QCS404 Jorge Ramirez-Ortiz
2018-12-17 9:46 ` [PATCH 01/13] clk: qcom: gcc: limit GPLL0_AO_OUT operating frequency Jorge Ramirez-Ortiz
2018-12-21 11:19 ` Taniya Das
2018-12-21 12:36 ` Jorge Ramirez
2018-12-21 17:58 ` Taniya Das
2018-12-21 19:28 ` Bjorn Andersson
2018-12-21 19:45 ` Jorge Ramirez
2018-12-21 21:40 ` Stephen Boyd
2018-12-21 21:45 ` Jorge Ramirez
2018-12-21 21:51 ` Stephen Boyd
2018-12-17 9:46 ` [PATCH 02/13] mbox: qcom: add APCS child device for QCS404 Jorge Ramirez-Ortiz
2019-01-17 6:25 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 03/13] mbox: qcom: replace integer with valid macro Jorge Ramirez-Ortiz
2019-01-17 6:25 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 04/13] dt-bindings: mailbox: qcom: Add clock-name optional property Jorge Ramirez-Ortiz
2018-12-20 21:37 ` Rob Herring
2019-01-17 6:44 ` Bjorn Andersson
2019-01-28 16:57 ` Jorge Ramirez
2019-01-28 17:46 ` Jorge Ramirez
2018-12-17 9:46 ` [PATCH 05/13] clk: qcom: apcs-msm8916: get parent clock names from DT Jorge Ramirez-Ortiz
2018-12-17 23:37 ` Stephen Boyd
2018-12-18 8:37 ` Jorge Ramirez
2018-12-18 14:35 ` Niklas Cassel
2018-12-26 9:20 ` Jorge Ramirez
2018-12-28 22:28 ` Stephen Boyd
2018-12-31 8:42 ` Jorge Ramirez
2019-01-17 6:54 ` Bjorn Andersson
2018-12-28 22:27 ` Stephen Boyd
2018-12-17 9:46 ` [PATCH 06/13] clk: qcom: hfpll: " Jorge Ramirez-Ortiz
2019-01-17 6:27 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 07/13] clk: qcom: hfpll: register as clock provider Jorge Ramirez-Ortiz
2019-01-17 6:28 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 08/13] clk: qcom: hfpll: CLK_IGNORE_UNUSED Jorge Ramirez-Ortiz
2019-01-17 6:33 ` Bjorn Andersson
2019-01-17 8:38 ` Jorge Ramirez [this message]
2019-01-17 10:08 ` Viresh Kumar
2019-01-17 10:46 ` Jorge Ramirez
2019-01-22 18:47 ` Stephen Boyd
2019-01-22 19:35 ` Jorge Ramirez
2018-12-17 9:46 ` [PATCH 09/13] arm64: dts: qcom: qcs404: Add OPP table Jorge Ramirez-Ortiz
2019-01-17 6:35 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 10/13] arm64: dts: qcom: qcs404: Add HFPLL node Jorge Ramirez-Ortiz
2018-12-17 19:39 ` Stephen Boyd
2019-01-17 6:38 ` Bjorn Andersson
2019-01-22 18:49 ` Stephen Boyd
2018-12-17 9:46 ` [PATCH 11/13] arm64: dts: qcom: qcs404: Add the clocks for APCS mux/divider Jorge Ramirez-Ortiz
2019-01-17 6:35 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 12/13] arm64: dts: qcom: qcs404: Add cpufreq support Jorge Ramirez-Ortiz
2019-01-17 6:36 ` Bjorn Andersson
2018-12-17 9:46 ` [PATCH 13/13] arm64: defconfig: Enable HFPLL Jorge Ramirez-Ortiz
2019-01-17 6:36 ` Bjorn Andersson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9abbe59b-433c-4e30-1e4d-b5eed3afc695@linaro.org \
--to=jorge.ramirez-ortiz@linaro.org \
--cc=amit.kucheria@linaro.org \
--cc=andy.gross@linaro.org \
--cc=arnd@arndb.de \
--cc=bjorn.andersson@linaro.org \
--cc=david.brown@linaro.org \
--cc=devicetree@vger.kernel.org \
--cc=enric.balletbo@collabora.com \
--cc=georgi.djakov@linaro.org \
--cc=heiko@sntech.de \
--cc=horms+renesas@verge.net.au \
--cc=jagan@amarulasolutions.com \
--cc=jassisinghbrar@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mturquette@baylibre.com \
--cc=niklas.cassel@linaro.org \
--cc=olof@lixom.net \
--cc=robh+dt@kernel.org \
--cc=sboyd@kernel.org \
--cc=sibis@codeaurora.org \
--cc=viresh.kumar@linaro.org \
--cc=vkoul@kernel.org \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).