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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT 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 2CA1DC43381 for ; Mon, 11 Mar 2019 14:12:37 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EFE8C2075C for ; Mon, 11 Mar 2019 14:12:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qlea6xYx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFE8C2075C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=q2u0UW8m7umc4W4Qhfm6y8BLLL7k2gq7yfmrxvb6+QE=; b=qlea6xYxk5LjvjTj9UV6NHkqy DO+/dXoR3R8qckmsk4OoPV94CwAu08KUI9opQY417RuzOWH+EsbLI3KIXhP4W2IHBLNGUYlHjiWNh wzB2K4qxUfvMUw0zceCyEHmntsP4fxSEbuE8aZDT4SShtKznYyYzOXqREHZdAtYAzOtc+pu0t6+XD O3gFEs6u7ABmvhH0F5CY50qjmQolJ87eB35sHmd1oO/wOQ5vPnagKtRx3oqpDNKY6ChjATLlmMzDo u9VRkUNvv4JPNMybhZ8xUTMXjCb+xflLDO750UFsG3NonRj4w3A3hm/G74z0Z/dRxdulpuILR+Hqv Lhm1Zj8aw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h3LfI-0004sn-4h; Mon, 11 Mar 2019 14:12:28 +0000 Received: from relay5-d.mail.gandi.net ([217.70.183.197]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h3LfD-0004sQ-W5 for linux-arm-kernel@lists.infradead.org; Mon, 11 Mar 2019 14:12:26 +0000 X-Originating-IP: 90.88.150.179 Received: from localhost (aaubervilliers-681-1-31-179.w90-88.abo.wanadoo.fr [90.88.150.179]) (Authenticated sender: maxime.ripard@bootlin.com) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id B296D1C0017; Mon, 11 Mar 2019 14:12:11 +0000 (UTC) Date: Mon, 11 Mar 2019 15:12:11 +0100 From: Maxime Ripard To: Jagan Teki Subject: Re: [PATCH v2 3/9] drm/sun4i: dsi: Change the start delay calculation Message-ID: <20190311141211.uhxtrrdkp3q3dvt5@flea> References: <6e5f72e68f47ca0223877464bf12f0c3f3978de8.1549619502.git-series.maxime.ripard@bootlin.com> MIME-Version: 1.0 In-Reply-To: User-Agent: NeoMutt/20180716 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190311_071224_335225_733C89FF X-CRM114-Status: GOOD ( 23.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bbrezillon@kernel.org, Maarten Lankhorst , dri-devel , Paul Kocialkowski , Chen-Yu Tsai , Sean Paul , Thomas Petazzoni , Jagan Teki , linux-arm-kernel Content-Type: multipart/mixed; boundary="===============4450036364996955666==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============4450036364996955666== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="6gv2u2dfivms4zdf" Content-Disposition: inline --6gv2u2dfivms4zdf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 07, 2019 at 11:24:01PM +0530, Jagan Teki wrote: > Hi Maxime, >=20 > On Fri, Feb 8, 2019 at 3:23 PM Maxime Ripard = wrote: > > > > The current calculation for the video start delay in the current DSI dr= iver > > is that it is the total vertical size, minus the front porch and sync l= ength, > > plus 1. This equals to the active vertical size plus the back porch plu= s 1. > > > > That 1 is coming in the Allwinner BSP from an variable that is set to 1. > > However, if we look at the Allwinner BSP more closely, and especially in > > the "legacy" code for the display (in drivers/video/sunxi/legacy/), we = can > > see that this variable is actually computed from the porches and the sy= nc > > minus 10, clamped between 8 and 100. > > > > This fixes the start delay symptom we've seen on some panels (vblank > > timeouts with vertical white stripes at the bottom of the panel). > > > > Signed-off-by: Maxime Ripard > > --- > > drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/s= un4i/sun6i_mipi_dsi.c > > index 380fc527a707..9471fa695ec7 100644 > > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c > > @@ -357,7 +357,9 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *d= si, > > static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi, > > struct drm_display_mode *mod= e) > > { > > - return mode->vtotal - (mode->vsync_end - mode->vdisplay) + 1; > > + u16 start =3D clamp(mode->vtotal - mode->vdisplay - 10, 8, 100); > > + > > + return mode->vtotal - (mode->vsync_end - mode->vdisplay) + star= t; > > } >=20 > As you stated in commit message about result as "active vertical size > + Back porch" which indeed correct in reverse way of previous code. > but the change seems incorrect to me. > > =3D> mode->vtotal - (mode->vsync_end - mode->vdisplay) + start > =3D> mode->vtotal - (mode->vsync_end - mode->vdisplay) + (mode->vtotal - > mode->vdisplay) # bypass 10 for now > =3D> mode->vtotal - mode->vsync_end + mode->vdisplay + mode->vtotal - > mode->vdisplay > =3D> (mode->vtotal - mode->vsync_end) + mode->vtotal > =3D> Back porch + mode->vtotal >=20 > but not > =3D> Back porch + mode->vdisplay Why do you think it should be this result? Maxime --=20 Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --6gv2u2dfivms4zdf Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXIZsuwAKCRDj7w1vZxhR xQhKAP97rFdiYd/MMkrr8iIg4ycpmJGWPQC4KR13WrNCMdoHJAEAqAF/a2ODC6Kg WPrjT+YuxLVhuHk9YgJscX/PHDLNQAE= =46JF -----END PGP SIGNATURE----- --6gv2u2dfivms4zdf-- --===============4450036364996955666== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============4450036364996955666==--