From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0368AC282C3 for ; Thu, 24 Jan 2019 14:01:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD7EC21855 for ; Thu, 24 Jan 2019 14:01:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XfrK273v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728327AbfAXOBx (ORCPT ); Thu, 24 Jan 2019 09:01:53 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:50379 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727799AbfAXOBw (ORCPT ); Thu, 24 Jan 2019 09:01:52 -0500 Received: by mail-wm1-f68.google.com with SMTP id n190so3262755wmd.0 for ; Thu, 24 Jan 2019 06:01:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Zly3uJj3nfd6LGkHaexN+XCtlqBu6G31R9osIiXcn5Y=; b=XfrK273vOJhFqVOf+1SgApy2Ctx3xStj+i54ORpCNbe8b7lmTkF4tOKmiZ6lis2+hC LsTHR17+hOdKX0h1SuhMnDFRP9jkCIzMZoNFEf4sreZzv+0czlzetDK6E0F7Cgho/7FG d42/ZluW2dpJ6LyFMJjupX6yO8G3OWftd4S17aIPb1zUH49AUqlHJD8gdPwwSDnxRT+t B5csQ74gc2Yp8mzwCzyF74+uiPxyDAQcc0PFDznl8O2KAodX0FadGK3CsZLDa3UuUKyD J40QmN9Xi/eudPMhRf/EX2ZJRI4j5gFambT3MdTajwP/5QsRQKHXcwnC+rCjzuki15PU BD0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Zly3uJj3nfd6LGkHaexN+XCtlqBu6G31R9osIiXcn5Y=; b=lQ4ojPfwMAEgmofU3baxjXWQ0jNij4LxOVh1fQSbVAsd/GHGKjenWvv8we7fQzAQDS Z0EzXDzhMICGd5A3dp0RCztM/IkOA9B+YFnRVfla/AnTCOJfrUSWnXKx9oPwUEaZ1Ixa 8pgf2wZnBm/eqaAQT90zxiB5CmbR2uOJe1Xqxw4RKa9Jgd8BdBR2uJCK1obhtMSgKBRi IRQaExUMMJxsfuNoZwEh31K3cbA3jFr+pJHajcYy56LPahtFCpYvLahF6D/ZA782IlHb uzJfVrnvscnjZURJmeUyjPr+Rlea0BOFhd7/3xLTF1HEWBIpFdZRr2DS96Ltu8mqlbs1 63+A== X-Gm-Message-State: AJcUukdU4zUr0AkIP1w96RZsvCoJ42QGNScAJaGL3w26339MZxZKueEv E/W43kBLPgKVvi71CqpQVhAngqytZJNgV8daI2Y= X-Google-Smtp-Source: ALg8bN4yXpHJwSOtUBiqISJ2R6T42zvZijTklQrw9xVkchJxEkh4WkGurfcpm+rih+t/nm+kp2hUROmX7VwwqDnwDH0= X-Received: by 2002:a1c:c87:: with SMTP id 129mr2653509wmm.116.1548338509915; Thu, 24 Jan 2019 06:01:49 -0800 (PST) MIME-Version: 1.0 References: <20190124120658.30288-1-ard.biesheuvel@linaro.org> <3cca35a9-c71c-a100-b29d-31ba0d1d10b1@amd.com> In-Reply-To: From: Alex Deucher Date: Thu, 24 Jan 2019 09:01:37 -0500 Message-ID: Subject: Re: [PATCH] drm: enable uncached DMA optimization for ARM and arm64 To: Ard Biesheuvel Cc: "Koenig, Christian" , "Zhou, David(ChunMing)" , Maxime Ripard , Benjamin Herrenschmidt , Carsten Haitzler , David Airlie , Maarten Lankhorst , dri-devel , "Daenzer, Michel" , "linux-kernel@vger.kernel.org" , Will Deacon , Christoph Hellwig , "Zhang, Jerry" , "Huang, Ray" , amd-gfx list , Daniel Vetter , Michael Ellerman , "Deucher, Alexander" , Sean Paul , "linux-arm-kernel@lists.infradead.org" , Robin Murphy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 24, 2019 at 9:00 AM Ard Biesheuvel wrote: > > On Thu, 24 Jan 2019 at 13:31, Koenig, Christian > wrote: > > > > Am 24.01.19 um 13:06 schrieb Ard Biesheuvel: > > > The DRM driver stack is designed to work with cache coherent devices > > > only, but permits an optimization to be enabled in some cases, where > > > for some buffers, both the CPU and the GPU use uncached mappings, > > > removing the need for DMA snooping and allocation in the CPU caches. > > > > > > The use of uncached GPU mappings relies on the correct implementation > > > of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU > > > will use cached mappings nonetheless. On x86 platforms, this does not > > > seem to matter, as uncached CPU mappings will snoop the caches in any > > > case. However, on ARM and arm64, enabling this optimization on a > > > platform where NoSnoop is ignored results in loss of coherency, which > > > breaks correct operation of the device. Since we have no way of > > > detecting whether NoSnoop works or not, just disable this > > > optimization entirely for ARM and arm64. > > > > > > Cc: Christian Koenig > > > Cc: Alex Deucher > > > Cc: David Zhou > > > Cc: Huang Rui > > > Cc: Junwei Zhang > > > Cc: Michel Daenzer > > > Cc: David Airlie > > > Cc: Daniel Vetter > > > Cc: Maarten Lankhorst > > > Cc: Maxime Ripard > > > Cc: Sean Paul > > > Cc: Michael Ellerman > > > Cc: Benjamin Herrenschmidt > > > Cc: Will Deacon > > > Cc: Christoph Hellwig > > > Cc: Robin Murphy > > > Cc: amd-gfx list > > > Cc: dri-devel > > > Reported-by: Carsten Haitzler > > > Signed-off-by: Ard Biesheuvel > > > > The subject line should probably read "disable uncached...". > > > > Ugh, of course ... > > > With that fixed the patch is Reviewed-by: Christian K=C3=B6nig > > . > > Same: Reviewed-by: Alex Deucher > > Thanks. > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20F97C282C6 for ; 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Thu, 24 Jan 2019 06:01:49 -0800 (PST) MIME-Version: 1.0 References: <20190124120658.30288-1-ard.biesheuvel@linaro.org> <3cca35a9-c71c-a100-b29d-31ba0d1d10b1@amd.com> In-Reply-To: From: Alex Deucher Date: Thu, 24 Jan 2019 09:01:37 -0500 Message-ID: Subject: Re: [PATCH] drm: enable uncached DMA optimization for ARM and arm64 To: Ard Biesheuvel X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190124_140151_357268_A92B82A4 X-CRM114-Status: GOOD ( 26.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Zhou, David\(ChunMing\)" , "Daenzer, Michel" , Carsten Haitzler , Maxime Ripard , Benjamin Herrenschmidt , Maarten Lankhorst , "linux-kernel@vger.kernel.org" , dri-devel , "Zhang, Jerry" , Christoph Hellwig , David Airlie , "Huang, Ray" , amd-gfx list , Daniel Vetter , Michael Ellerman , Will Deacon , "Deucher, Alexander" , Sean Paul , "Koenig, Christian" , "linux-arm-kernel@lists.infradead.org" , Robin Murphy Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVGh1LCBKYW4gMjQsIDIwMTkgYXQgOTowMCBBTSBBcmQgQmllc2hldXZlbAo8YXJkLmJpZXNo ZXV2ZWxAbGluYXJvLm9yZz4gd3JvdGU6Cj4KPiBPbiBUaHUsIDI0IEphbiAyMDE5IGF0IDEzOjMx LCBLb2VuaWcsIENocmlzdGlhbgo+IDxDaHJpc3RpYW4uS29lbmlnQGFtZC5jb20+IHdyb3RlOgo+ ID4KPiA+IEFtIDI0LjAxLjE5IHVtIDEzOjA2IHNjaHJpZWIgQXJkIEJpZXNoZXV2ZWw6Cj4gPiA+ IFRoZSBEUk0gZHJpdmVyIHN0YWNrIGlzIGRlc2lnbmVkIHRvIHdvcmsgd2l0aCBjYWNoZSBjb2hl cmVudCBkZXZpY2VzCj4gPiA+IG9ubHksIGJ1dCBwZXJtaXRzIGFuIG9wdGltaXphdGlvbiB0byBi ZSBlbmFibGVkIGluIHNvbWUgY2FzZXMsIHdoZXJlCj4gPiA+IGZvciBzb21lIGJ1ZmZlcnMsIGJv dGggdGhlIENQVSBhbmQgdGhlIEdQVSB1c2UgdW5jYWNoZWQgbWFwcGluZ3MsCj4gPiA+IHJlbW92 aW5nIHRoZSBuZWVkIGZvciBETUEgc25vb3BpbmcgYW5kIGFsbG9jYXRpb24gaW4gdGhlIENQVSBj YWNoZXMuCj4gPiA+Cj4gPiA+IFRoZSB1c2Ugb2YgdW5jYWNoZWQgR1BVIG1hcHBpbmdzIHJlbGll cyBvbiB0aGUgY29ycmVjdCBpbXBsZW1lbnRhdGlvbgo+ID4gPiBvZiB0aGUgUENJZSBOb1Nub29w IFRMUCBhdHRyaWJ1dGUgYnkgdGhlIHBsYXRmb3JtLCBvdGhlcndpc2UgdGhlIEdQVQo+ID4gPiB3 aWxsIHVzZSBjYWNoZWQgbWFwcGluZ3Mgbm9uZXRoZWxlc3MuIE9uIHg4NiBwbGF0Zm9ybXMsIHRo aXMgZG9lcyBub3QKPiA+ID4gc2VlbSB0byBtYXR0ZXIsIGFzIHVuY2FjaGVkIENQVSBtYXBwaW5n cyB3aWxsIHNub29wIHRoZSBjYWNoZXMgaW4gYW55Cj4gPiA+IGNhc2UuIEhvd2V2ZXIsIG9uIEFS TSBhbmQgYXJtNjQsIGVuYWJsaW5nIHRoaXMgb3B0aW1pemF0aW9uIG9uIGEKPiA+ID4gcGxhdGZv cm0gd2hlcmUgTm9Tbm9vcCBpcyBpZ25vcmVkIHJlc3VsdHMgaW4gbG9zcyBvZiBjb2hlcmVuY3ks IHdoaWNoCj4gPiA+IGJyZWFrcyBjb3JyZWN0IG9wZXJhdGlvbiBvZiB0aGUgZGV2aWNlLiBTaW5j ZSB3ZSBoYXZlIG5vIHdheSBvZgo+ID4gPiBkZXRlY3Rpbmcgd2hldGhlciBOb1Nub29wIHdvcmtz IG9yIG5vdCwganVzdCBkaXNhYmxlIHRoaXMKPiA+ID4gb3B0aW1pemF0aW9uIGVudGlyZWx5IGZv ciBBUk0gYW5kIGFybTY0Lgo+ID4gPgo+ID4gPiBDYzogQ2hyaXN0aWFuIEtvZW5pZyA8Y2hyaXN0 aWFuLmtvZW5pZ0BhbWQuY29tPgo+ID4gPiBDYzogQWxleCBEZXVjaGVyIDxhbGV4YW5kZXIuZGV1 Y2hlckBhbWQuY29tPgo+ID4gPiBDYzogRGF2aWQgWmhvdSA8RGF2aWQxLlpob3VAYW1kLmNvbT4K PiA+ID4gQ2M6IEh1YW5nIFJ1aSA8cmF5Lmh1YW5nQGFtZC5jb20+Cj4gPiA+IENjOiBKdW53ZWkg WmhhbmcgPEplcnJ5LlpoYW5nQGFtZC5jb20+Cj4gPiA+IENjOiBNaWNoZWwgRGFlbnplciA8bWlj aGVsLmRhZW56ZXJAYW1kLmNvbT4KPiA+ID4gQ2M6IERhdmlkIEFpcmxpZSA8YWlybGllZEBsaW51 eC5pZT4KPiA+ID4gQ2M6IERhbmllbCBWZXR0ZXIgPGRhbmllbEBmZndsbC5jaD4KPiA+ID4gQ2M6 IE1hYXJ0ZW4gTGFua2hvcnN0IDxtYWFydGVuLmxhbmtob3JzdEBsaW51eC5pbnRlbC5jb20+Cj4g PiA+IENjOiBNYXhpbWUgUmlwYXJkIDxtYXhpbWUucmlwYXJkQGJvb3RsaW4uY29tPgo+ID4gPiBD YzogU2VhbiBQYXVsIDxzZWFuQHBvb3JseS5ydW4+Cj4gPiA+IENjOiBNaWNoYWVsIEVsbGVybWFu IDxtcGVAZWxsZXJtYW4uaWQuYXU+Cj4gPiA+IENjOiBCZW5qYW1pbiBIZXJyZW5zY2htaWR0IDxi ZW5oQGtlcm5lbC5jcmFzaGluZy5vcmc+Cj4gPiA+IENjOiBXaWxsIERlYWNvbiA8d2lsbC5kZWFj b25AYXJtLmNvbT4KPiA+ID4gQ2M6IENocmlzdG9waCBIZWxsd2lnIDxoY2hAaW5mcmFkZWFkLm9y Zz4KPiA+ID4gQ2M6IFJvYmluIE11cnBoeSA8cm9iaW4ubXVycGh5QGFybS5jb20+Cj4gPiA+IENj OiBhbWQtZ2Z4IGxpc3QgPGFtZC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnPgo+ID4gPiBDYzog ZHJpLWRldmVsIDxkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnPgo+ID4gPiBSZXBvcnRl ZC1ieTogQ2Fyc3RlbiBIYWl0emxlciA8Q2Fyc3Rlbi5IYWl0emxlckBhcm0uY29tPgo+ID4gPiBT aWduZWQtb2ZmLWJ5OiBBcmQgQmllc2hldXZlbCA8YXJkLmJpZXNoZXV2ZWxAbGluYXJvLm9yZz4K PiA+Cj4gPiBUaGUgc3ViamVjdCBsaW5lIHNob3VsZCBwcm9iYWJseSByZWFkICJkaXNhYmxlIHVu Y2FjaGVkLi4uIi4KPiA+Cj4KPiBVZ2gsIG9mIGNvdXJzZSAuLi4KPgo+ID4gV2l0aCB0aGF0IGZp eGVkIHRoZSBwYXRjaCBpcyBSZXZpZXdlZC1ieTogQ2hyaXN0aWFuIEvDtm5pZwo+ID4gPGNocmlz dGlhbi5rb2VuaWdAYW1kLmNvbT4uCj4gPgoKU2FtZToKUmV2aWV3ZWQtYnk6IEFsZXggRGV1Y2hl ciA8YWxleGFuZGVyLmRldWNoZXJAYW1kLmNvbT4KCj4KPiBUaGFua3MuCj4gX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KPiBhbWQtZ2Z4IG1haWxpbmcgbGlz dAo+IGFtZC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCj4gaHR0cHM6Ly9saXN0cy5mcmVlZGVz a3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9hbWQtZ2Z4CgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdAps aW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVh ZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1hcm0ta2VybmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Deucher Subject: Re: [PATCH] drm: enable uncached DMA optimization for ARM and arm64 Date: Thu, 24 Jan 2019 09:01:37 -0500 Message-ID: References: <20190124120658.30288-1-ard.biesheuvel@linaro.org> <3cca35a9-c71c-a100-b29d-31ba0d1d10b1@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Ard Biesheuvel Cc: "Koenig, Christian" , "Zhou, David(ChunMing)" , Maxime Ripard , Benjamin Herrenschmidt , Carsten Haitzler , David Airlie , Maarten Lankhorst , dri-devel , "Daenzer, Michel" , "linux-kernel@vger.kernel.org" , Will Deacon , Christoph Hellwig , "Zhang, Jerry" , "Huang, Ray" , amd-gfx list , Daniel Vetter , Michael Ellerman List-Id: dri-devel@lists.freedesktop.org On Thu, Jan 24, 2019 at 9:00 AM Ard Biesheuvel wrote: > > On Thu, 24 Jan 2019 at 13:31, Koenig, Christian > wrote: > > > > Am 24.01.19 um 13:06 schrieb Ard Biesheuvel: > > > The DRM driver stack is designed to work with cache coherent devices > > > only, but permits an optimization to be enabled in some cases, where > > > for some buffers, both the CPU and the GPU use uncached mappings, > > > removing the need for DMA snooping and allocation in the CPU caches. > > > > > > The use of uncached GPU mappings relies on the correct implementation > > > of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU > > > will use cached mappings nonetheless. On x86 platforms, this does not > > > seem to matter, as uncached CPU mappings will snoop the caches in any > > > case. However, on ARM and arm64, enabling this optimization on a > > > platform where NoSnoop is ignored results in loss of coherency, which > > > breaks correct operation of the device. Since we have no way of > > > detecting whether NoSnoop works or not, just disable this > > > optimization entirely for ARM and arm64. > > > > > > Cc: Christian Koenig > > > Cc: Alex Deucher > > > Cc: David Zhou > > > Cc: Huang Rui > > > Cc: Junwei Zhang > > > Cc: Michel Daenzer > > > Cc: David Airlie > > > Cc: Daniel Vetter > > > Cc: Maarten Lankhorst > > > Cc: Maxime Ripard > > > Cc: Sean Paul > > > Cc: Michael Ellerman > > > Cc: Benjamin Herrenschmidt > > > Cc: Will Deacon > > > Cc: Christoph Hellwig > > > Cc: Robin Murphy > > > Cc: amd-gfx list > > > Cc: dri-devel > > > Reported-by: Carsten Haitzler > > > Signed-off-by: Ard Biesheuvel > > > > The subject line should probably read "disable uncached...". > > > > Ugh, of course ... > > > With that fixed the patch is Reviewed-by: Christian K=C3=B6nig > > . > > Same: Reviewed-by: Alex Deucher > > Thanks. > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx