From: Stanimir Varbanov <stanimir.varbanov@linaro.org>
To: "'Stephen Boyd'" <sboyd@codeaurora.org>,
Rajendra Nayak <rnayak@codeaurora.org>
Cc: Sricharan <sricharan@codeaurora.org>,
mturquette@baylibre.com, linux-clk@vger.kernel.org,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
stanimir.varbanov@linaro.org
Subject: Re: [PATCH 3/3] clk: qcom: Set BRANCH_HALT_DELAY flags for venus core0/1 clks
Date: Mon, 12 Dec 2016 17:40:34 +0200 [thread overview]
Message-ID: <904b110d-ca86-43f2-f96a-b57309100ad1@linaro.org> (raw)
In-Reply-To: <20161108223336.GK16026@codeaurora.org>
Hi Stephen,
On 11/09/2016 12:33 AM, 'Stephen Boyd' wrote:
> On 11/07, Rajendra Nayak wrote:
>>
>>
>> On 11/05/2016 01:48 AM, 'Stephen Boyd' wrote:
>>> Well I'm also curious which case is failing. Does turning on the
>>> clocks work after the gdsc is enabled? Does turning off the
>>> clocks fail because we don't know when the gdsc has turned off? I
>>> would hope that the firmware keeps the gdsc on when it's done
>>> processing things, goes idle, and hands back control to software.
>>> Right now I'm failing to see how the halt bits fail to toggle
>>> assuming that firmware isn't misbehaving and the kernel driver is
>>> power controlling in a coordinated manner with the firmware.
>>
>> What fails is turning ON the clocks after the gdsc is put under
>> hardware control (by fails I mean the halt checks fail to indicate
>> the clock is running, but register accesses etc thereafter suggest
>> the clocks are actually running)
>> The halt checks seem to work only while the gdsc is put in SW enabled
>> state.
>>
>
> Um... that is bad. I don't see how that is possible. It sounds
> like the clocks are not turning on when we're asking for them to
> turn on. The register accesses are always working because these
> subcore clks aren't required for register accesses. Most likely
> the GDSC for the subdomains is off (even after we thought we
> enabled it).
>
> Let's take a step back. The video hardware has three GDSCs. One
> for the main logic, and two for each subdomain. We're adding hw
> control for the two subdomains here. From what I can tell there
> isn't any hw control for the main domain. I see that there are
> two registers in the video hardware to control those subdomain hw
> enable signals that go to the GDSC. The reset value is OFF (not
> ON like was stated earlier), so it seems that if we switch the
> subdomain GDSCs on in these patches it will turn on for a short
> time, and then turn off when we switch into hw mode (by virtue of
> the way we enable the GDSC). Presumably we can assert these hw
> signal bits regardless of the subdomain power states, because
> otherwise we're in a chicken-egg situation for the firmware
> controlling this stuff.
>
> The proper sequence sounds like it should be:
>
> 1. Enable GDSC for main domain
> 2. Enable clocks for main domain (video_{core,maxi,ahb,axi}_clk)
> 3. Write the two registers to assert hw signal for subdomains
> 4. Enable GDSCs for two subdomains
> 5. Enable clocks for subdomains (video_subcore{0,1}_clk)
Do you think this sequence 'enable GDSC and the clocks behind it' is
valid for MMAGIC GDSCs too?
1. Enable GDSC for MMAGIC_VIDEO
2. Enable clocks (not sure which they are) -
msm8996_mmssnoc_axi_rpm_clk,
mmss_mmagic_ahb_clk
mmss_mmagic_cfg_ahb_clk,
mmss_mmagic_maxi_clk,
mmagic_video_axi_clk,
smmu_video_ahb_clk,
smmu_video_axi_clk
3. Continue with the sequence above.
--
regards,
Stan
prev parent reply other threads:[~2016-12-12 15:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-24 10:18 [PATCH 0/3] clk: qcom: Add support for hw controlled gdscs/clocks Sricharan R
2016-10-24 10:18 ` [PATCH 1/3] clk: qcom: gdsc: Add support for gdscs with HW control Sricharan R
2016-10-25 13:01 ` Stanimir Varbanov
2016-10-26 4:12 ` Sricharan
2016-11-02 0:18 ` Stephen Boyd
2016-11-02 6:50 ` Sricharan
2016-11-02 6:53 ` Sricharan
2016-11-02 17:59 ` 'Stephen Boyd'
2016-11-03 13:30 ` Sricharan
2016-11-03 20:05 ` 'Stephen Boyd'
2016-10-24 10:18 ` [PATCH 2/3] clk: qcom: Put venus core0/1 gdscs to hw control mode Sricharan R
2016-10-24 10:18 ` [PATCH 3/3] clk: qcom: Set BRANCH_HALT_DELAY flags for venus core0/1 clks Sricharan R
2016-11-03 20:34 ` Stephen Boyd
2016-11-04 9:09 ` Sricharan
2016-11-04 20:18 ` 'Stephen Boyd'
2016-11-07 5:48 ` Rajendra Nayak
2016-11-08 22:33 ` 'Stephen Boyd'
2016-11-09 16:56 ` Sricharan
2016-11-10 2:32 ` Rajendra Nayak
2016-11-10 3:28 ` Sricharan
2016-11-10 23:30 ` 'Stephen Boyd'
2016-11-14 3:51 ` Sricharan
2016-12-12 15:40 ` Stanimir Varbanov [this message]
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