From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH 1/6] iommu/tegra124: smmu: optionaly AHB enables SMMU Date: Mon, 16 Dec 2013 13:37:35 -0700 Message-ID: <52AF648F.70608@wwwdotorg.org> References: <1386246319-17851-1-git-send-email-hdoyu@nvidia.com> <1386246319-17851-2-git-send-email-hdoyu@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1386246319-17851-2-git-send-email-hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hiroshi Doyu , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 12/05/2013 05:25 AM, Hiroshi Doyu wrote: > SMMU used to depend on AHB bus. AHB driver needs to be populated and > AHB_XBAR_CTRL_SMMU_INIT_DONE bit needs to be set earliear than SMMU > being populated. Later Tegra SoC (>= T124) doesn't need AHB to enable > SMMU on AHB_XBAR_CTRL for AHB_XBAR_CTRL_SMMU_INIT_DONE any more. This > setting bit is now optional, depending on DT passing ahb phandle or > not. This patch should happen after 1/3, and the "platform data" should indicate whether tegra_ahb_enable_smmu() needs to be called, so that on Tegra30... > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c > @@ -1284,9 +1287,6 @@ static int tegra_smmu_probe(struct platform_device *pdev) > smmu->ahb = of_parse_phandle(dev->of_node, "nvidia,ahb", 0); > - if (!smmu->ahb) > - return -ENODEV; ... that error-checking is still in place, yet on Tegra124, of_parse_phandle() isn't even called.