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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 5F60BC433DF for ; Mon, 18 May 2020 08:13:52 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 39E59207D4 for ; Mon, 18 May 2020 08:13:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 39E59207D4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6488A89B48; Mon, 18 May 2020 08:13:51 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0B9B489B48 for ; Mon, 18 May 2020 08:13:50 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 4B3F2AB89; Mon, 18 May 2020 08:13:51 +0000 (UTC) Subject: Re: [PATCH 1/2] drm/shmem: Use cached mappings by default To: Daniel Vetter References: <20200513150312.21421-1-tzimmermann@suse.de> <20200513150312.21421-2-tzimmermann@suse.de> <20200514124050.GV206103@phenom.ffwll.local> <6cec8a8a-d642-cd93-906a-eafab49a12d7@suse.de> <20200515141044.GH206103@phenom.ffwll.local> From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= mQENBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAG0J1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPokBVAQTAQgAPhYh BHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJbOdLgAhsDBQkDwmcABQsJCAcCBhUKCQgLAgQWAgMB Ah4BAheAAAoJEGgNwR1TC3ojR80H/jH+vYavwQ+TvO8ksXL9JQWc3IFSiGpuSVXLCdg62AmR irxW+qCwNncNQyb9rd30gzdectSkPWL3KSqEResBe24IbA5/jSkPweJasgXtfhuyoeCJ6PXo clQQGKIoFIAEv1s8l0ggPZswvCinegl1diyJXUXmdEJRTWYAtxn/atut1o6Giv6D2qmYbXN7 mneMC5MzlLaJKUtoH7U/IjVw1sx2qtxAZGKVm4RZxPnMCp9E1MAr5t4dP5gJCIiqsdrVqI6i KupZstMxstPU//azmz7ZWWxT0JzgJqZSvPYx/SATeexTYBP47YFyri4jnsty2ErS91E6H8os Bv6pnSn7eAq5AQ0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRH UE9eosYbT6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgT RjP+qbU63Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+R dhgATnWWGKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zb ehDda8lvhFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r 12+lqdsAEQEAAYkBPAQYAQgAJhYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJbOdLgAhsMBQkD wmcAAAoJEGgNwR1TC3ojpfcIAInwP5OlcEKokTnHCiDTz4Ony4GnHRP2fXATQZCKxmu4AJY2 h9ifw9Nf2TjCZ6AMvC3thAN0rFDj55N9l4s1CpaDo4J+0fkrHuyNacnT206CeJV1E7NYntxU n+LSiRrOdywn6erjxRi9EYTVLCHcDhBEjKmFZfg4AM4GZMWX1lg0+eHbd5oL1as28WvvI/uI aMyV8RbyXot1r/8QLlWldU3NrTF5p7TMU2y3ZH2mf5suSKHAMtbE4jKJ8ZHFOo3GhLgjVrBW HE9JXO08xKkgD+w6v83+nomsEuf6C6LYrqY/tsZvyEX6zN8CtirPdPWu/VXNRYAl/lat7lSI 3H26qrE= Message-ID: <3e09cc7d-c609-e10a-3fe9-f40f3bbfaeaf@suse.de> Date: Mon, 18 May 2020 10:13:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200515141044.GH206103@phenom.ffwll.local> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , Sean Paul , Emil Velikov , dri-devel , Gerd Hoffmann , Sam Ravnborg Content-Type: multipart/mixed; boundary="===============0071580316==" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --===============0071580316== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bbX7xtiq38HQrZ827mU9oydf9VzfYU3DW" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --bbX7xtiq38HQrZ827mU9oydf9VzfYU3DW Content-Type: multipart/mixed; boundary="67mlwVANhpy136gtBHCw5CzyD0izA2gsK"; protected-headers="v1" From: Thomas Zimmermann To: Daniel Vetter Cc: Rob Herring , Sam Ravnborg , David Airlie , Emil Velikov , dri-devel , Gerd Hoffmann , Sean Paul Message-ID: <3e09cc7d-c609-e10a-3fe9-f40f3bbfaeaf@suse.de> Subject: Re: [PATCH 1/2] drm/shmem: Use cached mappings by default References: <20200513150312.21421-1-tzimmermann@suse.de> <20200513150312.21421-2-tzimmermann@suse.de> <20200514124050.GV206103@phenom.ffwll.local> <6cec8a8a-d642-cd93-906a-eafab49a12d7@suse.de> <20200515141044.GH206103@phenom.ffwll.local> In-Reply-To: <20200515141044.GH206103@phenom.ffwll.local> --67mlwVANhpy136gtBHCw5CzyD0izA2gsK Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Am 15.05.20 um 16:10 schrieb Daniel Vetter: > On Fri, May 15, 2020 at 08:58:02AM +0200, Thomas Zimmermann wrote: >> Hi >> >> Am 14.05.20 um 22:36 schrieb Rob Herring: >>> On Thu, May 14, 2020 at 7:40 AM Daniel Vetter wrote= : >>>> >>>> On Wed, May 13, 2020 at 05:03:11PM +0200, Thomas Zimmermann wrote: >>>>> SHMEM-buffer backing storage is allocated from system memory; which= is >>>>> typically cachable. Currently, only virtio uses cachable mappings; = udl >>>>> uses its own vmap/mmap implementation for cachable mappings. Other >>>>> drivers default to writecombine mappings. >>>> >>>> I'm pretty sure this breaks all these drivers. quick grep on a few >>>> functions says this is used by lima, panfrost, v3d. And they definit= ely >>>> need uncached/wc stuff afaiui. Or I'm completely missing something? >>> >> >> OK. I think I'll just make a patch that adds a .gem_create_object help= er >> that sets the map_cached flag. So drivers can opt-in. >> >>> Yes, that would be my guess. DMA is usually non-coherent on Arm. >> >> Can one of you give me some pointer to what you're looking at? For >> example, I grepped for use of vmap within lima and only found [1]. >> That's a for memcpy with no DMA involved. There's got to be something >> I'm missing. >> >> Best regards >> Thomas >> >> [1] >> https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/lima/lim= a_sched.c#n391 >=20 > $ git grep drm_gem_shmem_mmap >=20 > We also need correct access from userspace, otherwise the gpu is going = to > be sad. I've been thinking about this, and I think it means that we can never have cached mappings anywhere. Even if shmem supports it internally for most drivers, as soon as the page are exported, the importer could expect uncached memory. Given that, I think the correct thing to do is to udl's gem code and use the default implementation. Best regards Thomas > -Daniel >> >>> >>> Rob >>> >> >> --=20 >> Thomas Zimmermann >> Graphics Driver Developer >> SUSE Software Solutions Germany GmbH >> Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany >> (HRB 36809, AG N=C3=BCrnberg) >> Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer >> >=20 >=20 >=20 >=20 --=20 Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany (HRB 36809, AG N=C3=BCrnberg) Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer --67mlwVANhpy136gtBHCw5CzyD0izA2gsK-- --bbX7xtiq38HQrZ827mU9oydf9VzfYU3DW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEchf7rIzpz2NEoWjlaA3BHVMLeiMFAl7CQ7sACgkQaA3BHVML eiNTAQgAvvsZkoGMVzridqLRvskYrf+RUnLywiMJH1FAQQb9A4PhB4EhiKV9/R3G RmDGG6cdvZQvM+vAfg/03DtZ8Z//1cJa4Ryzab8gnaIMeONgQjxufzjZ2Ypv2wu5 LO0ZSJWTOJDwSydyDhDlxQFKNObz6OzSHwpRe8T9YHhmeW+AJQLzxRScsRzOAKBG eEFzn/tUNcMUUxOeDQJx/IHtDM10dvOzqYeZsQqIYP4xU/DGeramQqQClab7ofE8 C9OVZ2xJnch/y/oxNGoauYqKvFGrWA3aar5BXIzgXKxqDEqCSQrNgb9e9l1p0KGA z1XXZk34rIlR9qMaYX4Km2LQe/jOAw== =Qvj4 -----END PGP SIGNATURE----- --bbX7xtiq38HQrZ827mU9oydf9VzfYU3DW-- --===============0071580316== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel --===============0071580316==--