From patchwork Wed Oct 5 18:16:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marijn Suijten X-Patchwork-Id: 12999573 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 40DC5C433F5 for ; Wed, 5 Oct 2022 18:17:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4DC3810E73C; Wed, 5 Oct 2022 18:17:34 +0000 (UTC) Received: from m-r2.th.seeweb.it (m-r2.th.seeweb.it [5.144.164.171]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3554D10E741 for ; Wed, 5 Oct 2022 18:17:27 +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-r2.th.seeweb.it (Postfix) with ESMTPSA id 9BF103EF3C; Wed, 5 Oct 2022 20:17:24 +0200 (CEST) From: Marijn Suijten To: phone-devel@vger.kernel.org, Rob Clark , Dmitry Baryshkov , Vinod Koul Subject: [PATCH v2 7/7] drm/msm/dsi: Prevent signed BPG offsets from bleeding into adjacent bits Date: Wed, 5 Oct 2022 20:16:57 +0200 Message-Id: <20221005181657.784375-8-marijn.suijten@somainline.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221005181657.784375-1-marijn.suijten@somainline.org> References: <20221005181657.784375-1-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: freedreno@lists.freedesktop.org, Douglas Anderson , Thomas Zimmermann , Jami Kettunen , Vladimir Lypak , linux-arm-msm@vger.kernel.org, Konrad Dybcio , Abhinav Kumar , dri-devel@lists.freedesktop.org, Javier Martinez Canillas , David Airlie , Martin Botka , ~postmarketos/upstreaming@lists.sr.ht, AngeloGioacchino Del Regno , Alex Deucher , Marijn Suijten , 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 --- 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 4717d49d76be..b3cff3d3aa85 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1806,7 +1806,11 @@ 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 */