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[109.252.193.103]) by smtp.googlemail.com with ESMTPSA id t17sm749859ljd.35.2021.04.24.00.26.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 24 Apr 2021 00:26:21 -0700 (PDT) Subject: Re: [PATCH v2 0/5] iommu: Support identity mappings of reserved-memory regions To: Thierry Reding , Joerg Roedel , Rob Herring Cc: Will Deacon , Robin Murphy , Nicolin Chen , Krishna Reddy , devicetree@vger.kernel.org, iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org References: <20210423163234.3651547-1-thierry.reding@gmail.com> From: Dmitry Osipenko Message-ID: <869ec3a2-26df-2ce8-bd21-b681d6ef3985@gmail.com> Date: Sat, 24 Apr 2021 10:26:20 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210423163234.3651547-1-thierry.reding@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 23.04.2021 19:32, Thierry Reding пишет: > Hi, > > this is an updated proposal to solve the problem of passing memory > regions that are actively being accessed during boot. The particular > use-case that I need this for is when the bootloader has set up the > display controller to scan out a boot splash screen. During boot the > DMA/IOMMU glue code will attach devices to an IOMMU domain and by > doing so enable IOMMU translations. Typically this will be before a > device driver has had a chance to either disable the display > controller or set up a new framebuffer and map it to the IOMMU. Hello Thierry, Is it always safe to enable SMMU ASID in a middle of a DMA request made by a memory client? The memory controller supports blocking DMA requests, which we are already using for the memory hot-resetting. A block could be needed before ASID is toggled. This needs to be clarified. 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[109.252.193.103]) by smtp.googlemail.com with ESMTPSA id t17sm749859ljd.35.2021.04.24.00.26.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 24 Apr 2021 00:26:21 -0700 (PDT) Subject: Re: [PATCH v2 0/5] iommu: Support identity mappings of reserved-memory regions To: Thierry Reding , Joerg Roedel , Rob Herring References: <20210423163234.3651547-1-thierry.reding@gmail.com> From: Dmitry Osipenko Message-ID: <869ec3a2-26df-2ce8-bd21-b681d6ef3985@gmail.com> Date: Sat, 24 Apr 2021 10:26:20 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210423163234.3651547-1-thierry.reding@gmail.com> Content-Language: en-US Cc: devicetree@vger.kernel.org, Will Deacon , iommu@lists.linux-foundation.org, Nicolin Chen , linux-tegra@vger.kernel.org, Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" MjMuMDQuMjAyMSAxOTozMiwgVGhpZXJyeSBSZWRpbmcg0L/QuNGI0LXRgjoKPiBIaSwKPiAKPiB0 aGlzIGlzIGFuIHVwZGF0ZWQgcHJvcG9zYWwgdG8gc29sdmUgdGhlIHByb2JsZW0gb2YgcGFzc2lu ZyBtZW1vcnkKPiByZWdpb25zIHRoYXQgYXJlIGFjdGl2ZWx5IGJlaW5nIGFjY2Vzc2VkIGR1cmlu ZyBib290LiBUaGUgcGFydGljdWxhcgo+IHVzZS1jYXNlIHRoYXQgSSBuZWVkIHRoaXMgZm9yIGlz IHdoZW4gdGhlIGJvb3Rsb2FkZXIgaGFzIHNldCB1cCB0aGUKPiBkaXNwbGF5IGNvbnRyb2xsZXIg dG8gc2NhbiBvdXQgYSBib290IHNwbGFzaCBzY3JlZW4uIER1cmluZyBib290IHRoZQo+IERNQS9J T01NVSBnbHVlIGNvZGUgd2lsbCBhdHRhY2ggZGV2aWNlcyB0byBhbiBJT01NVSBkb21haW4gYW5k IGJ5Cj4gZG9pbmcgc28gZW5hYmxlIElPTU1VIHRyYW5zbGF0aW9ucy4gVHlwaWNhbGx5IHRoaXMg d2lsbCBiZSBiZWZvcmUgYQo+IGRldmljZSBkcml2ZXIgaGFzIGhhZCBhIGNoYW5jZSB0byBlaXRo ZXIgZGlzYWJsZSB0aGUgZGlzcGxheQo+IGNvbnRyb2xsZXIgb3Igc2V0IHVwIGEgbmV3IGZyYW1l YnVmZmVyIGFuZCBtYXAgaXQgdG8gdGhlIElPTU1VLgoKSGVsbG8gVGhpZXJyeSwKCklzIGl0IGFs d2F5cyBzYWZlIHRvIGVuYWJsZSBTTU1VIEFTSUQgaW4gYSBtaWRkbGUgb2YgYSBETUEgcmVxdWVz dCBtYWRlCmJ5IGEgbWVtb3J5IGNsaWVudD8KClRoZSBtZW1vcnkgY29udHJvbGxlciBzdXBwb3J0 cyBibG9ja2luZyBETUEgcmVxdWVzdHMsIHdoaWNoIHdlIGFyZQphbHJlYWR5IHVzaW5nIGZvciB0 aGUgbWVtb3J5IGhvdC1yZXNldHRpbmcuIEEgYmxvY2sgY291bGQgYmUgbmVlZGVkCmJlZm9yZSBB U0lEIGlzIHRvZ2dsZWQuIFRoaXMgbmVlZHMgdG8gYmUgY2xhcmlmaWVkLgpfX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwppb21tdSBtYWlsaW5nIGxpc3QKaW9t bXVAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRp b24ub3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU=