From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hiroshi Doyu Subject: Re: [PATCH v2 21/22] iommu/tegra: smmu: Support Multiple ASID Date: Tue, 30 Jul 2013 08:22:53 +0300 Message-ID: <20130730082253.be35a8ddadbe757100e92c10@nvidia.com> References: <1373021097-32420-1-git-send-email-hdoyu@nvidia.com> <1373021097-32420-22-git-send-email-hdoyu@nvidia.com> <51E8535A.30605@wwwdotorg.org> <20130729.133155.1836775489422797370.hdoyu@nvidia.com> <51F6A943.8000004@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51F6A943.8000004-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On Mon, 29 Jul 2013 19:41:23 +0200 Stephen Warren wrote: ... > > I think that this belongs to the system operation policy. Which H/W > > should be configured to which Address Space(AS). This put all AHB > > clients(PPCS) into AS[1](SYSTEM_PROTECTED), and the rest into > > AS[0](SYSTEM_DEFAULT). AHB clients are mainly traditional H/Ws like > > USB and SD/MMC so that they should be kept separated from the smart > > IOMMU clients like host1x. > > > > Is there any place to configure this kind of board specific policy > > rather than here? > > I'm not sure that answers the question I asked. > > I mean that the driver expects that two AS always exist; > SYSTEM_PROTECTED and SYSTEM_DEFAULT. However, the set of extant ASs is > IIRC defined by the DT content. What if the DT doesn't define two ASs? > Shouldn't there at least be an error-check for this case, so the driver > doesn't just blindly continue and access smmu_handle->map[1] when the > map[] array only has 1 entry? OK, now I got it. We can create multiple maps on the same AS in theory. So the limitation is only for how many maps S/W creaed. This can/should be checked only within kernel side. No constraints from DT. From mboxrd@z Thu Jan 1 00:00:00 1970 From: hdoyu@nvidia.com (Hiroshi Doyu) Date: Tue, 30 Jul 2013 08:22:53 +0300 Subject: [PATCH v2 21/22] iommu/tegra: smmu: Support Multiple ASID In-Reply-To: <51F6A943.8000004@wwwdotorg.org> References: <1373021097-32420-1-git-send-email-hdoyu@nvidia.com> <1373021097-32420-22-git-send-email-hdoyu@nvidia.com> <51E8535A.30605@wwwdotorg.org> <20130729.133155.1836775489422797370.hdoyu@nvidia.com> <51F6A943.8000004@wwwdotorg.org> Message-ID: <20130730082253.be35a8ddadbe757100e92c10@nvidia.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 29 Jul 2013 19:41:23 +0200 Stephen Warren wrote: ... > > I think that this belongs to the system operation policy. Which H/W > > should be configured to which Address Space(AS). This put all AHB > > clients(PPCS) into AS[1](SYSTEM_PROTECTED), and the rest into > > AS[0](SYSTEM_DEFAULT). AHB clients are mainly traditional H/Ws like > > USB and SD/MMC so that they should be kept separated from the smart > > IOMMU clients like host1x. > > > > Is there any place to configure this kind of board specific policy > > rather than here? > > I'm not sure that answers the question I asked. > > I mean that the driver expects that two AS always exist; > SYSTEM_PROTECTED and SYSTEM_DEFAULT. However, the set of extant ASs is > IIRC defined by the DT content. What if the DT doesn't define two ASs? > Shouldn't there at least be an error-check for this case, so the driver > doesn't just blindly continue and access smmu_handle->map[1] when the > map[] array only has 1 entry? OK, now I got it. We can create multiple maps on the same AS in theory. So the limitation is only for how many maps S/W creaed. This can/should be checked only within kernel side. No constraints from DT.