From patchwork Sun Oct 9 18:53:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marijn Suijten X-Patchwork-Id: 13002136 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 644BBC433F5 for ; Sun, 9 Oct 2022 18:53:49 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 631EC10E540; Sun, 9 Oct 2022 18:53:48 +0000 (UTC) Received: from relay01.th.seeweb.it (relay01.th.seeweb.it [IPv6:2001:4b7a:2000:18::162]) by gabe.freedesktop.org (Postfix) with ESMTPS id B47E110E540 for ; Sun, 9 Oct 2022 18:53:42 +0000 (UTC) Received: from localhost.localdomain (94-209-172-39.cable.dynamic.v4.ziggo.nl [94.209.172.39]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by m-r1.th.seeweb.it (Postfix) with ESMTPSA id C9E781F986; Sun, 9 Oct 2022 20:53:40 +0200 (CEST) From: Marijn Suijten To: phone-devel@vger.kernel.org Subject: [PATCH v3 10/10] drm/msm/dsi: Prevent signed BPG offsets from bleeding into adjacent bits Date: Sun, 9 Oct 2022 20:53:15 +0200 Message-Id: <20221009185316.462522-3-marijn.suijten@somainline.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221009184824.457416-1-marijn.suijten@somainline.org> References: <20221009184824.457416-1-marijn.suijten@somainline.org> MIME-Version: 1.0 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: Vinod Koul , Jami Kettunen , linux-arm-msm@vger.kernel.org, Vladimir Lypak , Konrad Dybcio , Abhinav Kumar , dri-devel@lists.freedesktop.org, Douglas Anderson , Martin Botka , ~postmarketos/upstreaming@lists.sr.ht, AngeloGioacchino Del Regno , Dmitry Baryshkov , Marijn Suijten , freedreno@lists.freedesktop.org, Sean Paul , linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The bpg_offset array contains negative BPG offsets which fill the full 8 bits of a char thanks to two's complement: this however results in those bits bleeding into the next field when the value is packed into DSC PPS by the drm_dsc_helper function, which only expects range_bpg_offset to contain 6-bit wide values. As a consequence random slices appear corrupted on-screen (tested on a Sony Tama Akatsuki device with sdm845). Use AND operators to limit these two's complement values to 6 bits, similar to the AMD and i915 drivers. Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data") Signed-off-by: Marijn Suijten Reviewed-by: Dmitry Baryshkov Reviewed-by: Abhinav Kumar --- drivers/gpu/drm/msm/dsi/dsi_host.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 46032c576a59..c5c2d70ac27d 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1804,7 +1804,11 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc for (i = 0; i < DSC_NUM_BUF_RANGES; i++) { dsc->rc_range_params[i].range_min_qp = min_qp[i]; dsc->rc_range_params[i].range_max_qp = max_qp[i]; - dsc->rc_range_params[i].range_bpg_offset = bpg_offset[i]; + /* + * Range BPG Offset contains two's-complement signed values that fill + * 8 bits, yet the registers and DCS PPS field are only 6 bits wide. + */ + dsc->rc_range_params[i].range_bpg_offset = bpg_offset[i] & DSC_RANGE_BPG_OFFSET_MASK; } dsc->initial_offset = 6144; /* Not bpp 12 */