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 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 88634FB519E for ; Tue, 7 Apr 2026 07:02:04 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BE61910E2D6; Tue, 7 Apr 2026 07:02:03 +0000 (UTC) Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) by gabe.freedesktop.org (Postfix) with ESMTPS id 92CFE10E2D6 for ; Tue, 7 Apr 2026 07:02:02 +0000 (UTC) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1wA0Rl-0006G9-7N; Tue, 07 Apr 2026 09:02:01 +0200 Received: from lupine.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::4e] helo=lupine) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wA0Rk-0048Zo-2v; Tue, 07 Apr 2026 09:02:00 +0200 Received: from pza by lupine with local (Exim 4.98.2) (envelope-from ) id 1wA0Rk-00000000CqD-3TTF; Tue, 07 Apr 2026 09:02:00 +0200 Message-ID: <7ae7cad05e1d0894772bc76d7de242d94ad356da.camel@pengutronix.de> Subject: Re: [PATCH] drm/imx/ipuv3: do not adjust hactive for non-8-pixel-aligned modes From: Philipp Zabel To: Magnus =?ISO-8859-1?Q?H=F6rlin?= Cc: dri-devel@lists.freedesktop.org, imx@lists.linux.dev Date: Tue, 07 Apr 2026 09:02:00 +0200 In-Reply-To: <20260406153654.2094908-1-magnus@alefors.se> References: <20260406153654.2094908-1-magnus@alefors.se> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2-0+deb13u1 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: dri-devel@lists.freedesktop.org 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mo, 2026-04-06 at 17:36 +0200, Magnus H=C3=B6rlin wrote: > The IPUv3 display driver rounds up hactive to 8-pixel alignment in > mode_set_nofb(), stealing pixels from the front porch. > ipu_src_rect_width() applies the same rounding to the IDMAC read > width. While this keeps the DC and IDMAC in sync, it causes the > display to receive more active pixels than the mode specifies. >=20 > On fixed-pixel displays whose native width is not 8-pixel aligned > (e.g. 854x480), the extra pixels cause visible skewing: each > scanline is offset, making vertical lines lean. >=20 > Remove both alignment overrides. The IDMAC and DC now use the exact > mode width. This partially reverts 94dfec48fca7 ("drm/imx: Add 8 pixel alignment fix") [1] without mentioning it, so I assume this patch breaks imx6dl- b105pv2. [1] https://lore.kernel.org/all/20210428222953.235280-6-sebastian.reichel@c= ollabora.com/ > The DMA burst size is already adapted to arbitrary > widths by ipu_calculate_bursts(), so no alignment is required at > the pixel level. The reference manual mentions burst size (NPB) has to be a multiple of 8 pixels at least for planar and semi-planar YUV formats. Without the width alignment, ipu_calculate_bursts() doesn't guarantee this. > Demote the DC warning about non-8-aligned hactive to dev_dbg, since > it is informational rather than indicative of a problem. >=20 > Signed-off-by: Magnus H=C3=B6rlin I wonder why the 8-pixel alignment check in ipu_di_adjust_videomode() which has not been removed, doesn't cause ipu_crtc_mode_fixup() to fail. regards Philipp