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[109.252.91.252]) by smtp.googlemail.com with ESMTPSA id q17sm1518034lfd.37.2020.10.03.07.06.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 03 Oct 2020 07:06:43 -0700 (PDT) Subject: Re: [PATCH v5 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device() To: Nicolin Chen , thierry.reding@gmail.com, joro@8bytes.org Cc: vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20201003065947.18671-1-nicoleotsuka@gmail.com> <20201003065947.18671-3-nicoleotsuka@gmail.com> From: Dmitry Osipenko Message-ID: <4a5a5b1c-080a-327a-1e2f-dc087948e1a1@gmail.com> Date: Sat, 3 Oct 2020 17:06:42 +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: <20201003065947.18671-3-nicoleotsuka@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 03.10.2020 09:59, Nicolin Chen пишет: > static int tegra_smmu_of_xlate(struct device *dev, > struct of_phandle_args *args) > { > + struct platform_device *iommu_pdev = of_find_device_by_node(args->np); > + struct tegra_mc *mc = platform_get_drvdata(iommu_pdev); > u32 id = args->args[0]; > > + put_device(&iommu_pdev->dev); > + > + if (!mc || !mc->smmu) > + return -EPROBE_DEFER; I'm not very excited by seeing code in the patches that can't be explained by the patch authors and will appreciate if you could provide a detailed explanation about why this NULL checking is needed because I think it is unneeded, especially given that other IOMMU drivers don't have such check. I'm asking this question second time now, please don't ignore review comments next time.