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From: houlong wei <houlong.wei@mediatek.com>
To: Eizan Miyamoto <eizan@chromium.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "wenst@chromium.org" <wenst@chromium.org>,
	"Yong Wu (吴勇)" <Yong.Wu@mediatek.com>,
	"enric.balletbo@collabora.com" <enric.balletbo@collabora.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>,
	"Andrew-CT Chen (陳智迪)" <Andrew-CT.Chen@mediatek.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Minghsiu Tsai (蔡明修)" <Minghsiu.Tsai@mediatek.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	houlong.wei@mediatek.com
Subject: Re: [PATCH v6 4/9] media: mtk-mdp: don't pm_run_time_get/put for master comp in clock_on
Date: Mon, 16 Aug 2021 09:10:33 +0800	[thread overview]
Message-ID: <bef757c4a081bfb87aa3b429970e628641bf95a5.camel@mediatek.com> (raw)
In-Reply-To: <20210802220943.v6.4.Ifd87681955689a08cce4c65e72ee5e8c6d09af95@changeid>

On Mon, 2021-08-02 at 20:12 +0800, Eizan Miyamoto wrote:
> The original intent of commit 86698b9505bbc ("media: mtk-mdp: convert
> mtk_mdp_dev.comp array to list") was to create a list to track all
> the
> MDP components that needed to have their clocks enabled/disabled when
> calling mtk_mdp_comp_clock_on/off. However, there was a bug inside
> mtk_mdp_register_component where the args to a call to list_add were
> swapped. The result is that only one component was added to
> mtk_mdp_dev.comp_list because comp_list was instead being
> repeatedly added to the single element lists headed by each
> mtk_mdp_comp.
> 
> The order of the args to list_add in mtk_mdp_register_component was
> fixed in https://patchwork.kernel.org/patch/11742895/ (Fix Null
> pointer
> dereference when calling list_add).
> 
> Then, as a result of https://patchwork.kernel.org/patch/11530769/
> (mtk-mdp: use pm_runtime in MDP component driver) if all the
> components
> are added to the component list, the mdp "master" / rdma0 component
> ends up having pm_runtime_get_sync() called on it twice recursively:
> 
>     rpm_resume+0x694/0x8f8
>     __pm_runtime_resume+0x7c/0xa0 ***NOTE***
>     mtk_mdp_comp_clock_on+0x48/0x104 [mtk_mdp]
>     mtk_mdp_pm_resume+0x2c/0x44 [mtk_mdp]
>     pm_generic_runtime_resume+0x34/0x48
>     __genpd_runtime_resume+0x6c/0x80
>     genpd_runtime_resume+0x104/0x1ac
>     __rpm_callback+0x120/0x238
>     rpm_callback+0x34/0x8c
>     rpm_resume+0x7a0/0x8f8
>     __pm_runtime_resume+0x7c/0xa0 ***NOTE***
>     mtk_mdp_m2m_start_streaming+0x2c/0x3c [mtk_mdp]
> 
> (The calls to pm_runtime_get_sync are inlined and correspond to the
> calls to __pm_runtime_resume). It is not correct to have
> pm_runtime_get_sync called recursively and the second call will block
> indefinitely.
> 
> As a result of all that, this change factors
> mtk_mdp_comp_clock_on/off
> into mtk_mdp_comp_power_on/off and moves the calls to
> pm_runtime_get/put into the power_on/off functions.
> 
> This change then special-cases the master/rdma0 MDP component and
> does
> these things:
> - the master/rdma0 component is not added to mtk_mdp_dev.comp_list
> - the master/rdma0 component has its clocks (*but not power*) toggled
>   by mtk_mpd_comp_clock_on/off inside mtk_mdp_clock_on/off.
> - the other components have their clocks *and* power toggled with
>   mtk_mdp_comp_power_on/off.
> 
> This change introduces the assumption that mtk_mdp_pm_resume will
> always be called though a callback from pm_runtime_get_sync made on
> the
> master / rdma0 component.
> 
> Signed-off-by: Eizan Miyamoto <eizan@chromium.org>
> ---
> 

Reviewed-by: Houlong Wei <houlong.wei@mediatek.com>

> (no changes since v1)
> 
[...]

  parent reply	other threads:[~2021-08-16  1:10 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02 12:12 [PATCH v6 0/9] Refactor MTK MDP driver into core/components Eizan Miyamoto
2021-08-02 12:12 ` [PATCH v6 1/9] mtk-mdp: propagate errors from clock_on Eizan Miyamoto
2021-08-03 10:26   ` Enric Balletbo Serra
2021-08-05  6:06   ` Dafna Hirschfeld
2021-08-09  3:23     ` Eizan Miyamoto
2021-08-09  7:42       ` Dafna Hirschfeld
2021-08-16  0:46   ` houlong wei
2021-08-02 12:12 ` [PATCH v6 2/9] mtk-mdp: add driver to probe mdp components Eizan Miyamoto
2021-08-03 10:26   ` Enric Balletbo Serra
2021-08-05  6:40   ` Dafna Hirschfeld
2021-08-09  3:23     ` Eizan Miyamoto
2021-08-09  7:53       ` Dafna Hirschfeld
2021-08-11 11:15         ` Eizan Miyamoto
2021-08-16  1:05   ` houlong wei
2021-08-02 12:12 ` [PATCH v6 3/9] mtk-mdp: use pm_runtime in MDP component driver Eizan Miyamoto
2021-08-03 10:26   ` Enric Balletbo Serra
2021-08-16  1:07   ` houlong wei
2021-08-02 12:12 ` [PATCH v6 4/9] media: mtk-mdp: don't pm_run_time_get/put for master comp in clock_on Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-16  1:10   ` houlong wei [this message]
2021-08-02 12:12 ` [PATCH v6 5/9] mtk-mdp: make mdp driver to be loadable by platform_device_register*() Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-16  1:15   ` houlong wei
2021-08-16  3:37   ` houlong wei
2021-08-02 12:12 ` [PATCH v6 6/9] soc: mediatek: mmsys: instantiate mdp virtual device from mmsys Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-16  1:18   ` houlong wei
2021-08-02 12:12 ` [PATCH v6 7/9] media: mtk-mdp: use mdp-rdma0 alias to point to MDP master Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-03 11:46     ` Eizan Miyamoto
2021-08-16  3:00   ` houlong wei
2021-08-16  4:52     ` houlong wei
2021-08-18  7:50       ` Eizan Miyamoto
2021-08-18 15:42         ` houlong wei
2021-08-18  7:43     ` Eizan Miyamoto
2021-08-18 15:34       ` houlong wei
2021-08-02 12:12 ` [PATCH v6 8/9] dts: mtk-mdp: remove mediatek,vpu property from primary MDP device Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-02 12:12 ` [PATCH v6 9/9] dt-bindings: mediatek: remove vpu requirement from mtk-mdp Eizan Miyamoto
2021-08-03 10:27   ` Enric Balletbo Serra
2021-08-06 21:47   ` Rob Herring
2021-08-03 10:29 ` [PATCH v6 0/9] Refactor MTK MDP driver into core/components Enric Balletbo Serra

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