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[109.252.91.213]) by smtp.googlemail.com with ESMTPSA id z19-v6sm427749ljk.20.2018.09.25.06.42.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Sep 2018 06:42:01 -0700 (PDT) Subject: Re: [PATCH v4 18/20] iommu/tegra: gart: Don't detach devices from inactive domains To: Thierry Reding Cc: Jonathan Hunter , Joerg Roedel , Rob Herring , Robin Murphy , iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180924004153.8232-1-digetx@gmail.com> <20180924004153.8232-19-digetx@gmail.com> <20180924110047.GO21032@ulmo> <8be80297-3b13-ece6-a5bf-873cc7877989@gmail.com> <20180925100424.GG7097@ulmo> From: Dmitry Osipenko Message-ID: <57704439-66f3-2548-093c-b5a2fc04ee14@gmail.com> Date: Tue, 25 Sep 2018 16:41:55 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180925100424.GG7097@ulmo> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/25/18 1:04 PM, Thierry Reding wrote: > On Mon, Sep 24, 2018 at 09:05:48PM +0300, Dmitry Osipenko wrote: >> On 9/24/18 2:00 PM, Thierry Reding wrote: >>> On Mon, Sep 24, 2018 at 03:41:51AM +0300, Dmitry Osipenko wrote: >>>> There could be unlimited number of allocated domains, but only one domain >>>> can be active at a time. Hence devices must be detached only from the >>>> active domain. >>>> >>>> Signed-off-by: Dmitry Osipenko >>>> --- >>>> drivers/iommu/tegra-gart.c | 8 +++++--- >>>> 1 file changed, 5 insertions(+), 3 deletions(-) >>> >>> Do we have a mechanism of switching out different domains? I don't think >>> we do, so I'm wondering if perhaps a better solution to this would be to >>> just refuse to create more than one domain in the first place. That >>> would also allow us to get rid of the global variable gart_handle. >> >> That's what was done in v1, Robin Murphy suggested that it will be >> better not to restrict allocation of unpopulated domains. It is >> mentioned in the changelog, see comment to v2 changes. > > Okay, fine. Thanks, taking as ACK.