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[109.252.193.102]) by smtp.googlemail.com with ESMTPSA id b6sm526314lff.15.2021.04.28.00.55.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Apr 2021 00:55:17 -0700 (PDT) Subject: Re: [PATCH v2 0/5] iommu: Support identity mappings of reserved-memory regions To: Mikko Perttunen , 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: <8fb43dff-1fd8-3bbb-86e9-19fb3064ec54@gmail.com> Date: Wed, 28 Apr 2021 10:55:17 +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: 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 28.04.2021 08:57, Mikko Perttunen пишет: > On 4/28/21 8:51 AM, Dmitry Osipenko wrote: >> 23.04.2021 19:32, Thierry Reding пишет: >>> Note that there will be no new releases of the bootloader for earlier >>> devices, so adding support for these new DT bindings will not be >>> practical. The bootloaders on those devices do pass information about >>> the active framebuffer via the kernel command-line, so we may want to >>> add code to create reserved regions in the IOMMU based on that. >> >> Since this change requires a bootloader update anyways, why it's not >> possible to fix the bootloader properly, making it to stop all the DMA >> activity before jumping into kernel? >> > > That is not desirable, as then we couldn't have seamless > bootloader-kernel boot splash transition. The seamless transition should be more complicated since it should require to read out the hardware state in order to convert it into DRM state + display panel needs to stay ON. It's a bit questionable whether this is really needed, so far this is not achievable in mainline. Nevertheless, it will be good to have an early simple-framebuffer, which I realized only after sending out the message. 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[109.252.193.102]) by smtp.googlemail.com with ESMTPSA id b6sm526314lff.15.2021.04.28.00.55.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Apr 2021 00:55:17 -0700 (PDT) Subject: Re: [PATCH v2 0/5] iommu: Support identity mappings of reserved-memory regions To: Mikko Perttunen , Thierry Reding , Joerg Roedel , Rob Herring References: <20210423163234.3651547-1-thierry.reding@gmail.com> From: Dmitry Osipenko Message-ID: <8fb43dff-1fd8-3bbb-86e9-19fb3064ec54@gmail.com> Date: Wed, 28 Apr 2021 10:55:17 +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: 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" MjguMDQuMjAyMSAwODo1NywgTWlra28gUGVydHR1bmVuINC/0LjRiNC10YI6Cj4gT24gNC8yOC8y MSA4OjUxIEFNLCBEbWl0cnkgT3NpcGVua28gd3JvdGU6Cj4+IDIzLjA0LjIwMjEgMTk6MzIsIFRo aWVycnkgUmVkaW5nINC/0LjRiNC10YI6Cj4+PiBOb3RlIHRoYXQgdGhlcmUgd2lsbCBiZSBubyBu ZXcgcmVsZWFzZXMgb2YgdGhlIGJvb3Rsb2FkZXIgZm9yIGVhcmxpZXIKPj4+IGRldmljZXMsIHNv IGFkZGluZyBzdXBwb3J0IGZvciB0aGVzZSBuZXcgRFQgYmluZGluZ3Mgd2lsbCBub3QgYmUKPj4+ IHByYWN0aWNhbC4gVGhlIGJvb3Rsb2FkZXJzIG9uIHRob3NlIGRldmljZXMgZG8gcGFzcyBpbmZv cm1hdGlvbiBhYm91dAo+Pj4gdGhlIGFjdGl2ZSBmcmFtZWJ1ZmZlciB2aWEgdGhlIGtlcm5lbCBj b21tYW5kLWxpbmUsIHNvIHdlIG1heSB3YW50IHRvCj4+PiBhZGQgY29kZSB0byBjcmVhdGUgcmVz ZXJ2ZWQgcmVnaW9ucyBpbiB0aGUgSU9NTVUgYmFzZWQgb24gdGhhdC4KPj4KPj4gU2luY2UgdGhp cyBjaGFuZ2UgcmVxdWlyZXMgYSBib290bG9hZGVyIHVwZGF0ZSBhbnl3YXlzLCB3aHkgaXQncyBu b3QKPj4gcG9zc2libGUgdG8gZml4IHRoZSBib290bG9hZGVyIHByb3Blcmx5LCBtYWtpbmcgaXQg dG8gc3RvcCBhbGwgdGhlIERNQQo+PiBhY3Rpdml0eSBiZWZvcmUganVtcGluZyBpbnRvIGtlcm5l bD8KPj4KPiAKPiBUaGF0IGlzIG5vdCBkZXNpcmFibGUsIGFzIHRoZW4gd2UgY291bGRuJ3QgaGF2 ZSBzZWFtbGVzcwo+IGJvb3Rsb2FkZXIta2VybmVsIGJvb3Qgc3BsYXNoIHRyYW5zaXRpb24uCgpU aGUgc2VhbWxlc3MgdHJhbnNpdGlvbiBzaG91bGQgYmUgbW9yZSBjb21wbGljYXRlZCBzaW5jZSBp dCBzaG91bGQKcmVxdWlyZSB0byByZWFkIG91dCB0aGUgaGFyZHdhcmUgc3RhdGUgaW4gb3JkZXIg dG8gY29udmVydCBpdCBpbnRvIERSTQpzdGF0ZSArIGRpc3BsYXkgcGFuZWwgbmVlZHMgdG8gc3Rh eSBPTi4gSXQncyBhIGJpdCBxdWVzdGlvbmFibGUgd2hldGhlcgp0aGlzIGlzIHJlYWxseSBuZWVk ZWQsIHNvIGZhciB0aGlzIGlzIG5vdCBhY2hpZXZhYmxlIGluIG1haW5saW5lLgoKTmV2ZXJ0aGVs ZXNzLCBpdCB3aWxsIGJlIGdvb2QgdG8gaGF2ZSBhbiBlYXJseSBzaW1wbGUtZnJhbWVidWZmZXIs IHdoaWNoCkkgcmVhbGl6ZWQgb25seSBhZnRlciBzZW5kaW5nIG91dCB0aGUgbWVzc2FnZS4KX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KaW9tbXUgbWFpbGlu ZyBsaXN0CmlvbW11QGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBzOi8vbGlzdHMubGlu dXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2lvbW11