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[91.76.12.16]) by smtp.googlemail.com with ESMTPSA id z186sm2970938lfa.6.2020.07.23.07.01.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Jul 2020 07:01:44 -0700 (PDT) Subject: Re: [PATCH 5/7] i2c: tegra: enable second level clock gating To: Krishna Yarlagadda , linux-i2c@vger.kernel.org, thierry.reding@gmail.com Cc: jonathanh@nvidia.com, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, ldewangan@nvidia.com, smohammed@nvidia.com, rgumasta@nvidia.com References: <1595506733-10307-1-git-send-email-kyarlagadda@nvidia.com> <1595506733-10307-5-git-send-email-kyarlagadda@nvidia.com> From: Dmitry Osipenko Message-ID: <1f51823f-09ea-80d5-69dd-7772474a3fb1@gmail.com> Date: Thu, 23 Jul 2020 17:01:43 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1595506733-10307-5-git-send-email-kyarlagadda@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org 23.07.2020 15:18, Krishna Yarlagadda пишет: > Enable Second Level Clock Gating feature for supported chips. > With SLCG enabled, software need not control clocks anymore > and leave clocks enabled always on. What problem is solved by this patch? If there is no real problem, then I'm not sure that this is a worthwhile patch. Please explain. ... > @@ -1932,7 +1946,8 @@ static int __maybe_unused tegra_i2c_suspend(struct device *dev) > struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev); > int err = 0; > > - i2c_mark_adapter_suspended(&i2c_dev->adapter); Why i2c_mark_adapter_suspended() is removed? > + if (i2c_dev->is_clkon_always) > + clk_disable(i2c_dev->div_clk); Why clk needs to be disabled on suspend? > if (!pm_runtime_status_suspended(dev)) > err = tegra_i2c_runtime_suspend(dev); > @@ -1968,6 +1983,15 @@ static int __maybe_unused tegra_i2c_resume(struct device *dev) > return err; > } > > + if (i2c_dev->is_clkon_always) { > + err = clk_enable(i2c_dev->div_clk); > + if (err < 0) { > + dev_err(i2c_dev->dev, "clock enable failed %d\n", > + err); > + return err; > + } > + } Would be nice if it all could be wrapped into tegra_i2c_div_clk_enable/disable() helpers. > i2c_mark_adapter_resumed(&i2c_dev->adapter); > > return 0; >