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Tue, 16 Jul 2019 20:48:12 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20190716114812epsmtip1ab6e8f6885a4894f29421f436be0c765~x4MdYFEv81787417874epsmtip1g; Tue, 16 Jul 2019 11:48:12 +0000 (GMT) Subject: Re: [PATCH v4 04/24] PM / devfreq: tegra30: Drop write-barrier To: Dmitry Osipenko , Thierry Reding , MyungJoo Ham , Kyungmin Park , Jonathan Hunter , Tomeu Vizoso Cc: linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <1aaa2e01-dcb3-7499-61ef-0b5fe4b94e77@samsung.com> Date: Tue, 16 Jul 2019 20:51:19 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190707223303.6755-5-digetx@gmail.com> Content-Language: en-US Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA02Se2xLURzHnfb29k7Ujs7jZwnmysLKrFdX7mQV8SwmW0K8YuZmu2lnfaW3 EyNiVNDFY0yyKFrPGCJeQ9thUfNcbMz7MRZb4hEhw8Y2Ru/uxP77/L75/s75fc/5UXL1KTKW yrW5eKeNs9Bkb+Li9QRt4tpgYqb2aJ2MPdnciNiN3kMEe2/DJyX7MLSPZL9tq0Ks57uXZF+u LyPZtpCPYLefqiMnRxkD9UeQMeitVxq3uT+Txu3lJ5Dx27mhGYolealmnsvhnXG8Lduek2sz Geg587KmZunHa5lEJoWdQMfZOCtvoKelZSTOyLVEBqLjVnKW/IiUwQkCnTQp1WnPd/FxZrvg MtC8I8fiSHGMFTirkG8zjc22WycyWu04fcS4PM8cqmgkHKdjVl39oSlEb6OLUBQFOBl2NQWI ItSbUuMAgidl12RS8RXBwacVSqloRVDa+UTxr+VPwzulyGp8BUG7Z4XEXxBcaE0pQhQVg2dC aYdG7O2POxF42tyk6JHjxXA9eFImMok1UPn+WZcejYfD45+NSGQVngSH7h8kRCZwPJwPbO66 dwBeBHerfITk6Qd39jR1cRTWQ/NzP5LOHwQvmvwyiYeB+8JeuTgE4D8k+F4/UEoBpkHH01ZS 4hj4eKu8W4+FDzs2dfMaOH6nipSatyAor7zfnV4HlUdLZGJKOU6A06EkSR4OwY793UP0hc8t WxWiBbAKtmxSS5YR8LChXibxYDi82UMWI9rbI463RwRvjwje/5cdQMQJNJB3CFYTLzAOXc+/ Poe6VlUzIYDO1KSFEaYQ3Ud1+/KYTLWCWykUWMMIKDndX2VoGZ2pVuVwBat5pz3LmW/hhTDS R157pzx2QLY9svg2VxajH6fT6dhkZryeYehBKt+vhEw1NnEuPo/nHbzzX5+MiootRAtTZdF7 VKN26/L8r6YUezoXKGB2rX/prMKGN+3JBYKX14f33lpX0qduRK+pGxvnNuP45BLf4PQf+huT zQnm+uoQ1JbPTWtv25k0Pdx88dKyRYGrAw2GTw3Pz4ycv2+00n3DXxr/yPTbUeMeQp59lB1c U1FYfMyTWvvu5uWC9K3VLTQhmDlGI3cK3F90pMzFwAMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJIsWRmVeSWpSXmKPExsWy7bCSnG7NTt1Yg6cHVSxWf3zMaNEyaxGL xdmmN+wWl3fNYbP43HuE0aLzyyw2i9uNK9gsfu6ax2LRt/YSmwOnx467Sxg9ds66y+7R2/yO zaNvyypGj8+b5AJYo7hsUlJzMstSi/TtErgydu1+zFKwXrhi33etBsZH/F2MnBwSAiYS/x88 Z+9i5OIQEtjNKLHj/gZGiISkxLSLR5m7GDmAbGGJw4eLIWreMkrsOvucESQuLOAuMf23Fkhc RKCJSWJT7wV2kF5mgUiJnrlb2CAaNjNKXLm3iQkkwSagJbH/xQ02EJtfQFHi6o/HYMt4Bewk Fl1YyAJiswioSmze0c4KYosKREhMuraTBaJGUOLkzCdgNqeAqcTHm/MZIZapS/yZd4kZwhaX uPVkPhOELS/RvHU28wRG4VlI2mchaZmFpGUWkpYFjCyrGCVTC4pz03OLDQsM81LL9YoTc4tL 89L1kvNzNzGCI0xLcwfj5SXxhxgFOBiVeHhP7NGJFWJNLCuuzD3EKMHBrCTCa/tVO1aINyWx siq1KD++qDQntfgQozQHi5I479O8Y5FCAumJJanZqakFqUUwWSYOTqkGxsDzE33WHZniq/K+ ab+TVoJ4xGrWJkVh7/oqXsOqukMaTWe/+83PDCx7dGXObKHfLBWXv6aJCrmerZ9WWtXPvOV7 jFbN+jvpp9NU1A1nm4Y4fo/1UYg9czQ7xtrV9/XKlV3SBp/YVKaVR3zvuNBle51v0WSZR+rb /1WvnzyVc2uOmt58814mJZbijERDLeai4kQAHCWz5KwCAAA= X-CMS-MailID: 20190716114812epcas1p2b2b823e4c878060cfe751a094897fa0f X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20190707223727epcas4p450b911e20b59833cf68975099c7e4bfa References: <20190707223303.6755-1-digetx@gmail.com> <20190707223303.6755-5-digetx@gmail.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hi Dmitry, On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote: > There is no need in a write-barrier now, given that interrupt masking is > handled by CPU's GIC now. Hence we know exactly that interrupt won't fire > after stopping the devfreq's governor. In other cases we don't care about > potential buffering of the writes to hardware and thus there is no need to > stall CPU. > > Signed-off-by: Dmitry Osipenko > --- > drivers/devfreq/tegra30-devfreq.c | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c > index 5e606ae3f238..4be7858c33bc 100644 > --- a/drivers/devfreq/tegra30-devfreq.c > +++ b/drivers/devfreq/tegra30-devfreq.c > @@ -230,12 +230,6 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra, > ACTMON_DEV_LOWER_WMARK); > } > > -static void actmon_write_barrier(struct tegra_devfreq *tegra) > -{ > - /* ensure the update has reached the ACTMON */ > - readl(tegra->regs + ACTMON_GLB_STATUS); > -} > - > static void actmon_isr_device(struct tegra_devfreq *tegra, > struct tegra_devfreq_device *dev) > { > @@ -287,8 +281,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra, > device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL); > > device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS); > - > - actmon_write_barrier(tegra); > } > > static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra, > @@ -376,8 +368,6 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb, > tegra_devfreq_update_wmark(tegra, dev); > } > > - actmon_write_barrier(tegra); > - > return NOTIFY_OK; > } > > @@ -423,8 +413,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra) > for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) > tegra_actmon_configure_device(tegra, &tegra->devices[i]); > > - actmon_write_barrier(tegra); > - > enable_irq(tegra->irq); > } > > @@ -439,8 +427,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra) > device_writel(&tegra->devices[i], ACTMON_INTR_STATUS_CLEAR, > ACTMON_DEV_INTR_STATUS); > } > - > - actmon_write_barrier(tegra); > } > > static int tegra_devfreq_target(struct device *dev, unsigned long *freq, > Reviewed-by: Chanwoo Choi -- Best Regards, Chanwoo Choi Samsung Electronics