From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Date: Tue, 13 Dec 2016 07:33:24 +0000 Subject: Re: [RFC PATCH 0/3] staging: remove fbdev drivers Message-Id: <1481614404.27088.64.camel@redhat.com> List-Id: References: <1479888193-23908-1-git-send-email-tomi.valkeinen@ti.com> <1481158879.26959.41.camel@kernel.crashing.org> <20161208101005.6ufl3d4qvwprosju@phenom.ffwll.local> <1481232519.26959.49.camel@kernel.crashing.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dave Airlie Cc: Thomas Petazzoni , Linux Fbdev development list , Teddy Wang , LKML , dri-devel , Tomi Valkeinen , Greg Kroah-Hartman , Sudip Mukherjee , Arnaud Patard Hi, > The acceleration that most of the 2D things provide isn't ever that > great, and shadowing is a lot more effective if done properly. That is probably true for anything pci-ish, because those devices are optimized for memory writes and reads are horribly slow. So you surely want avoid device memory reads and shadowing is a effective way to do this. On arm hardware the tradeoff may look quite different, the cpus are relatively slow and I think most arm gpus don't have dedicated device memory ... cheers, Gerd From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Subject: Re: [RFC PATCH 0/3] staging: remove fbdev drivers Date: Tue, 13 Dec 2016 08:33:24 +0100 Message-ID: <1481614404.27088.64.camel@redhat.com> References: <1479888193-23908-1-git-send-email-tomi.valkeinen@ti.com> <1481158879.26959.41.camel@kernel.crashing.org> <20161208101005.6ufl3d4qvwprosju@phenom.ffwll.local> <1481232519.26959.49.camel@kernel.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTPS id B0A316E4D1 for ; Tue, 13 Dec 2016 08:49:41 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Dave Airlie Cc: Thomas Petazzoni , Linux Fbdev development list , Teddy Wang , LKML , dri-devel , Tomi Valkeinen , Greg Kroah-Hartman , Sudip Mukherjee , Arnaud Patard List-Id: dri-devel@lists.freedesktop.org ICBIaSwKCj4gVGhlIGFjY2VsZXJhdGlvbiB0aGF0IG1vc3Qgb2YgdGhlIDJEIHRoaW5ncyBwcm92 aWRlIGlzbid0IGV2ZXIgdGhhdAo+IGdyZWF0LCBhbmQgc2hhZG93aW5nIGlzIGEgbG90IG1vcmUg ZWZmZWN0aXZlIGlmIGRvbmUgcHJvcGVybHkuCgpUaGF0IGlzIHByb2JhYmx5IHRydWUgZm9yIGFu eXRoaW5nIHBjaS1pc2gsIGJlY2F1c2UgdGhvc2UgZGV2aWNlcyBhcmUKb3B0aW1pemVkIGZvciBt ZW1vcnkgd3JpdGVzIGFuZCByZWFkcyBhcmUgaG9ycmlibHkgc2xvdy4gIFNvIHlvdSBzdXJlbHkK d2FudCBhdm9pZCBkZXZpY2UgbWVtb3J5IHJlYWRzIGFuZCBzaGFkb3dpbmcgaXMgYSBlZmZlY3Rp dmUgd2F5IHRvIGRvCnRoaXMuCgpPbiBhcm0gaGFyZHdhcmUgdGhlIHRyYWRlb2ZmIG1heSBsb29r IHF1aXRlIGRpZmZlcmVudCwgdGhlIGNwdXMgYXJlCnJlbGF0aXZlbHkgc2xvdyBhbmQgSSB0aGlu ayBtb3N0IGFybSBncHVzIGRvbid0IGhhdmUgZGVkaWNhdGVkIGRldmljZQptZW1vcnkgLi4uCgpj aGVlcnMsCiAgR2VyZAoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Au b3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRl dmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932724AbcLMItr convert rfc822-to-8bit (ORCPT ); Tue, 13 Dec 2016 03:49:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57986 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932305AbcLMItl (ORCPT ); Tue, 13 Dec 2016 03:49:41 -0500 Message-ID: <1481614404.27088.64.camel@redhat.com> Subject: Re: [RFC PATCH 0/3] staging: remove fbdev drivers From: Gerd Hoffmann To: Dave Airlie Cc: Benjamin Herrenschmidt , Thomas Petazzoni , Linux Fbdev development list , Teddy Wang , Greg Kroah-Hartman , LKML , dri-devel , Tomi Valkeinen , Sudip Mukherjee , Arnaud Patard Date: Tue, 13 Dec 2016 08:33:24 +0100 In-Reply-To: References: <1479888193-23908-1-git-send-email-tomi.valkeinen@ti.com> <1481158879.26959.41.camel@kernel.crashing.org> <20161208101005.6ufl3d4qvwprosju@phenom.ffwll.local> <1481232519.26959.49.camel@kernel.crashing.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Mime-Version: 1.0 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 13 Dec 2016 08:49:41 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, > The acceleration that most of the 2D things provide isn't ever that > great, and shadowing is a lot more effective if done properly. That is probably true for anything pci-ish, because those devices are optimized for memory writes and reads are horribly slow. So you surely want avoid device memory reads and shadowing is a effective way to do this. On arm hardware the tradeoff may look quite different, the cpus are relatively slow and I think most arm gpus don't have dedicated device memory ... cheers, Gerd