From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [PATCH v2 03/19] PM / devfreq: tegra: Don't ignore clk errors Date: Tue, 16 Apr 2019 10:52:44 +0900 Message-ID: <1e4038d1-0fd3-f6d2-4e01-d34b16aeddbd@samsung.com> References: <20190415145505.18397-1-digetx@gmail.com> <20190415145505.18397-4-digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190415145505.18397-4-digetx@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-tegra@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