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Tue, 16 Apr 2019 10:51:49 +0900 (KST) Received: from epsmtrp1.samsung.com (unknown [182.195.40.13]) by epcas1p1.samsung.com (KnoxPortal) with ESMTPA id 20190416015149epcas1p15bb993e9d8436dd766a9ab7b4c6838ef~V0WxJ4zEQ0996509965epcas1p1h; Tue, 16 Apr 2019 01:51:49 +0000 (GMT) Received: from epsmgms1p1new.samsung.com (unknown [182.195.42.41]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20190416015149epsmtrp1bc7bc8f31f648e9939cf57ca52b65bdb~V0WxGI4J_3124131241epsmtrp1P; Tue, 16 Apr 2019 01:51:49 +0000 (GMT) X-AuditID: b6c32a37-f31ff7000000102f-6e-5cb535354105 Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgms1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id 68.CE.03692.53535BC5; Tue, 16 Apr 2019 10:51:49 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20190416015149epsmtip1dff38df0cbdff2f118e9fd0e08ca8836~V0Ww8ZIN20286502865epsmtip1J; Tue, 16 Apr 2019 01:51:49 +0000 (GMT) Subject: Re: [PATCH v2 03/19] PM / devfreq: tegra: Don't ignore clk errors To: Dmitry Osipenko , Thierry Reding , Jonathan Hunter , MyungJoo Ham , Kyungmin Park , Tomeu Vizoso Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <1e4038d1-0fd3-f6d2-4e01-d34b16aeddbd@samsung.com> Date: Tue, 16 Apr 2019 10:52:44 +0900 User-Agent: Mozilla/5.0 (X11; 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charset="utf-8" CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20190415145811epcas2p45772ac8ae956928341d76b80d3fa5e91 References: <20190415145505.18397-1-digetx@gmail.com> <20190415145505.18397-4-digetx@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 19. 4. 15. 오후 11:54, Dmitry Osipenko wrote: > The clk_set_min_rate() could fail and in this case clk_set_rate() sets > rate to 0, which may drop EMC rate to minimum and make machine very > difficult to use. > > Signed-off-by: Dmitry Osipenko > --- > drivers/devfreq/tegra-devfreq.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c > index 0c0909fba545..69581c9082d4 100644 > --- a/drivers/devfreq/tegra-devfreq.c > +++ b/drivers/devfreq/tegra-devfreq.c > @@ -487,6 +487,7 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq, > struct tegra_devfreq *tegra = dev_get_drvdata(dev); > struct dev_pm_opp *opp; > unsigned long rate; > + int err; > > opp = devfreq_recommended_opp(dev, freq, flags); > if (IS_ERR(opp)) { > @@ -496,8 +497,13 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq, > rate = dev_pm_opp_get_freq(opp); > dev_pm_opp_put(opp); > > - clk_set_min_rate(tegra->emc_clock, rate); > - clk_set_rate(tegra->emc_clock, 0); > + err = clk_set_min_rate(tegra->emc_clock, rate); > + if (err) > + return err; > + > + err = clk_set_rate(tegra->emc_clock, 0); > + if (err) Why don't you restore the previous minimum clock for tegra->emc_clock when failed to execute 'clk_set_rate(tegra->emc_clock, 0);'? I think that if you control the restoring the previous minimum clock, it is more nice to handle the error handling. > + return err; > > return 0; > } > -- Best Regards, Chanwoo Choi Samsung Electronics