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Fri, 28 Aug 2020 10:35:20 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20200828013519epsmtip2cb4c7fb54f955a09e82cac16c65c1415~vSrG0NQaN0625906259epsmtip2I; Fri, 28 Aug 2020 01:35:19 +0000 (GMT) Subject: Re: [PATCH v5 13/36] PM / devfreq: tegra30: Use MC timings for building OPP table To: Dmitry Osipenko , Thierry Reding , Jonathan Hunter , Georgi Djakov , Rob Herring , Michael Turquette , Stephen Boyd , Peter De Schrijver , MyungJoo Ham , Kyungmin Park , Mikko Perttunen Cc: linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <2a255211-5426-d78f-d266-cdb958f4c658@samsung.com> Date: Fri, 28 Aug 2020 10:47:46 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <1de8aa41-8001-cf46-026c-b00f8df0b9a3@gmail.com> Content-Language: en-US Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrBJsWRmVeSWpSXmKPExsWy7bCmnm5EvEe8QdsSI4t3n56yWsw/co7V YvXHx4wWV76+Z7OYvncTm0XLrEUsFmeb3rBbXN41h83ic+8RRovOL7PYLC6ecrW43biCzWLS 2qmMFq17j7Bb/Lu2kcXi5655LA4CHu9vtLJ77Jx1l93j0rk/zB6bVnWyedy5tofN4373cSaP 3uZ3bB59W1YxenzeJBfAGZVtk5GamJJapJCal5yfkpmXbqvkHRzvHG9qZmCoa2hpYa6kkJeY m2qr5OIToOuWmQP0hpJCWWJOKVAoILG4WEnfzqYov7QkVSEjv7jEVim1ICWnwLJArzgxt7g0 L10vOT/XytDAwMgUqDAhO2Nx4ySmgvN8FR/udrE2ML7i7mLk5JAQMJFoe7CftYuRi0NIYAej xMMt/UwgCSGBT4wSc7ZoQCS+MUq8/tPBDNNxccN0RojEXkaJ9ncXmSGc94wSTQv/sINUCQvE SJyZt5EdJCEicIRZYnXncUaQBLPADEaJO3uUQWw2AS2J/S9usIHY/AKKEld/PAar4RWwk5j8 4xtYnEVAVeLa28tgN4kKhEmc3NYCVSMocXLmExYQm1PAVmLd/jUsEPPFJW49mc8EYctLNG+d DXadhMB/Dompp38DNXMAOS4SGz87Q7wjLPHq+BZ2CFtK4mV/G5RdLbHy5BE2iN4ORokt+y+w QiSMJfYvncwEModZQFNi/S59iLCixM7fc6F+5JN497WHFWIVr0RHmxBEibLE5Qd3mSBsSYnF 7Z1sExiVZiH5ZhaSD2Yh+WAWwrIFjCyrGMVSC4pz01OLDQuMkWN7EyM4iWuZ72Cc9vaD3iFG Jg7GQ4wSHMxKIryvj7rHC/GmJFZWpRblxxeV5qQWH2I0BYbvRGYp0eR8YB7JK4k3NDUyNja2 MDE0MzU0VBLnfXhLIV5IID2xJDU7NbUgtQimj4mDU6qByYib2++EtvOLZX+/Vcxcq7R3blRs I2vBnh2Zq6wFVLoSQ5O/CU+dsePmukmeb0NXrZQJirqRn1NouVb91d8ff4Imq9xgvTulzmLR BEHlHbJvL7VZr4x737P4+eNglcSPAd8WMDaqGR05/3d1G/8/foZGl2T7+Xq1SbIzg00nqUgu 4nqeu/BipNfVCY92REqvnZR2UjOt8q7JXZZn/7fJMxREvln26s2WaKUEv0lme57KpHzOTir1 VCmsKZ0jd93GYMHVfblicmGGcmdSJk9OTdYJC+WV0J6TxZgWIdJ1bXa4q/7Ut0pzu9ND77L4 9u3Z5J2hImw46Yqhm8MEqcOma/gqWyU3M60wrzeK+HNIiaU4I9FQi7moOBEAfmno22sEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKIsWRmVeSWpSXmKPExsWy7bCSvG5EvEe8wZlOJot3n56yWsw/co7V YvXHx4wWV76+Z7OYvncTm0XLrEUsFmeb3rBbXN41h83ic+8RRovOL7PYLC6ecrW43biCzWLS 2qmMFq17j7Bb/Lu2kcXi5655LA4CHu9vtLJ77Jx1l93j0rk/zB6bVnWyedy5tofN4373cSaP 3uZ3bB59W1YxenzeJBfAGcVlk5Kak1mWWqRvl8CVsbhxElPBeb6KD3e7WBsYX3F3MXJySAiY SFzcMJ2xi5GLQ0hgN6PE9u3bmSESkhLTLh4FsjmAbGGJw4eLIWreMkpM2PkIrEZYIEbizLyN 7CAJEYFjzBKbTp9mAnGYBWYwSvzZAJEREpjDJHF0zjw2kBY2AS2J/S9ugNn8AooSV388ZgSx eQXsJCb/+AYWZxFQlbj29jITiC0qECaxc8ljJogaQYmTM5+wgNicArYS6/avAbOZBdQl/sy7 xAxhi0vcejKfCcKWl2jeOpt5AqPwLCTts5C0zELSMgtJywJGllWMkqkFxbnpucWGBYZ5qeV6 xYm5xaV56XrJ+bmbGMExraW5g3H7qg96hxiZOBgPMUpwMCuJ8L4+6h4vxJuSWFmVWpQfX1Sa k1p8iFGag0VJnPdG4cI4IYH0xJLU7NTUgtQimCwTB6dUA1Ob1I9zPnO5j8zS4d637czuA4wW 5XOKmsoOZL5omCt+7cvyRcFzL5QavJoSuPdN3zn3rfl+zRKnGDh2xrk5lwtm/5itoSE26dJh xVLZ/kVHF3Vf2yehcTF93ZNpDblPr642Wv/g+PZHtxoD2atnJlhZzvEO/BUsm7rSgttBYVWn Y5tXfKPb+6tukrsqD1dttXmoUeBXMlFKdFPgvdbv6TN01wbdmVK5pUHPoXj3zGV3G/eukb/6 TD/6jv7JX/rGD761TH4nfT+Pf0nN9MnCTEs7mF4Gnt6gvJHn6dzIyU47LzDI/uBtEFhrnL49 b8VmWVvNY5/PtbZxvhRm1efxNP6tz1Qf9ftOu0RpSJuScbQSS3FGoqEWc1FxIgB9F1inWAMA AA== X-CMS-MailID: 20200828013520epcas1p2bc32bd495a6427a36bc7e016dea98e27 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: 20200814000944epcas1p3dfd0104c5fa640695dfcd4949f6b1818 References: <20200814000621.8415-1-digetx@gmail.com> <20200814000621.8415-14-digetx@gmail.com> <1b0d75fe-79af-70eb-8450-999a3bc72bac@samsung.com> <1de8aa41-8001-cf46-026c-b00f8df0b9a3@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 8/15/20 1:47 AM, Dmitry Osipenko wrote: > 14.08.2020 05:02, Chanwoo Choi пишет: >> Hi Dmitry, >> >> I add the minor comment. Except of some comments, it looks good to me. > > Hello, Chanwoo! Thank you for the review! > > ... >>> +struct tegra_devfreq_soc_data { >>> + const char *mc_compatible; >>> +}; >>> + >>> +static const struct tegra_devfreq_soc_data tegra30_soc = { >>> + .mc_compatible = "nvidia,tegra30-mc", >>> +}; >>> + >>> +static const struct tegra_devfreq_soc_data tegra124_soc = { >>> + .mc_compatible = "nvidia,tegra124-mc", >>> +}; > . >>> + soc_data = of_device_get_match_data(&pdev->dev); >> >> I think that better to check whether 'soc_data' is not NULL. > > It's a quite common misconception among kernel developers that > of_device_get_match_data() may "accidentally" return NULL, but it > couldn't if every driver's of_match[] entry has a non-NULL .data field > and because the OF-matching already happened at the driver's probe-time > [1], which is the case of this driver. > > [1] https://elixir.bootlin.com/linux/v5.8/source/drivers/of/device.c#L189 > > Hence the NULL-checking is unnecessary. > > When I first encountered the of_device_get_match_data(), I was also > thinking that adding the NULL-checks is a good idea, but later on > somebody pointed out to me (maybe Thierry) that it's unnecessary to do. OK. Thanks. > >>> + >>> + mc = tegra_get_memory_controller(soc_data->mc_compatible); >>> + if (IS_ERR(mc)) >>> + return PTR_ERR(mc); >> >> You better to add error log. > > In practice we should get only -EPROBE_DEFER here ever. I'll consider > adding the message in the next revision, at least just for consistency. In order to handle -EPROBE_DEFER, recommend the using of dev_err_probe(). (snip) -- Best Regards, Chanwoo Choi Samsung Electronics