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=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 72F37C43441 for ; Mon, 19 Nov 2018 14:18:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45D3D20851 for ; Mon, 19 Nov 2018 14:18:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45D3D20851 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sntech.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729480AbeKTAma (ORCPT ); Mon, 19 Nov 2018 19:42:30 -0500 Received: from gloria.sntech.de ([185.11.138.130]:38384 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727324AbeKTAma (ORCPT ); Mon, 19 Nov 2018 19:42:30 -0500 Received: from we0660.dip.tu-dresden.de ([141.76.178.148] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.0:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1gOkNm-0007v7-2B; Mon, 19 Nov 2018 15:18:34 +0100 From: Heiko Stuebner To: Damian Kos Cc: Chris Zhong , Sandy Huang , David Airlie , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/rockchip: fix for mailbox read size Date: Mon, 19 Nov 2018 15:18:33 +0100 Message-ID: <7088529.fTnRXqZmiP@phil> In-Reply-To: <1541518625-25984-1-git-send-email-dkos@cadence.com> References: <1541518625-25984-1-git-send-email-dkos@cadence.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 6. November 2018, 16:37:05 CET schrieb Damian Kos: > Some of the functions (like cdn_dp_dpcd_read, cdn_dp_get_edid_block) > allow to read 64KiB, but the cdn_dp_mailbox_read_receive, that is > used by them, can read only up to 255 bytes at once. Normally, it's > not a big issue as DPCD or EDID reads won't (hopefully) exceed that > value. > The real issue here is the revocation list read during the HDCP > authentication process. (problematic use case: > https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/drm/rockchip/cdn-dp-reg.c#1152) > The list can reach 127*5+4 bytes (num devs * 5 bytes per ID/Bksv + > 4 bytes of an additional info). > In other words - CTSes with HDCP Repeater won't pass without this > fix. Oh, and the driver will most likely stop working (best case > scenario). > > Signed-off-by: Damian Kos applied to drm-misc-next Thanks Heiko