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=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 990ADC433B4 for ; Tue, 13 Apr 2021 15:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71709613B6 for ; Tue, 13 Apr 2021 15:51:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346171AbhDMPvj (ORCPT ); Tue, 13 Apr 2021 11:51:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:40584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345974AbhDMPvf (ORCPT ); Tue, 13 Apr 2021 11:51:35 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5E620613B6; Tue, 13 Apr 2021 15:51:15 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lWLJp-007Gjb-Ai; Tue, 13 Apr 2021 16:51:13 +0100 Date: Tue, 13 Apr 2021 16:51:12 +0100 Message-ID: <87tuoambdb.wl-maz@kernel.org> From: Marc Zyngier To: Peter Geis Cc: Thomas Gleixner , "open list:ARM/Rockchip SoC..." , Linux Kernel Mailing List Subject: Re: [RFC] ITS fails to allocate on rk3568/rk3566 In-Reply-To: References: <871rbeo7wf.wl-maz@kernel.org> <87y2dmmggt.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: pgwipeout@gmail.com, tglx@linutronix.de, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 13 Apr 2021 16:03:51 +0100, Peter Geis wrote: > > On Tue, Apr 13, 2021 at 10:01 AM Marc Zyngier wrote: [...] > > What happens if you hack all the allocations to happen in the low 4GB > > of the PA space? > > It seems to work correctly. > The downstream hacks used GFP_DMA32 which gets discarded by > kmalloc_fix_flags on certain allocations. > Switching to GFP_DMA seems to have satisfied it, but it feels wrong > using this code. > Need to check the corner cases to make sure I'm not missing something. The problem is that GFP_DMA doesn't always mean the same thing. Overall, we need to hear from Rockchip about the exact nature of the problem, and then we *may* be able to work something out. I'd also like to understand whether it is broken because you happen to have pre-release silicon that will never make it into the wild, or if this is the real thing that is going to ship on millions of devices. Thanks, M. -- Without deviation from the norm, progress is not possible.