Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752844AbdHOXxF (ORCPT ); Tue, 15 Aug 2017 19:53:05 -0400 Received: from anholt.net ([50.246.234.109]:58572 "EHLO anholt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752322AbdHOXxC (ORCPT ); Tue, 15 Aug 2017 19:53:02 -0400 From: Eric Anholt To: dri-devel@lists.freedesktop.org, Archit Taneja , Andrzej Hajda , Laurent Pinchart , Thierry Reding Cc: linux-kernel@vger.kernel.org, Eric Anholt Subject: [PATCH v6 2/5] drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math. Date: Tue, 15 Aug 2017 16:47:19 -0700 Message-Id: <20170815234722.20700-2-eric@anholt.net> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170815234722.20700-1-eric@anholt.net> References: <20170815234722.20700-1-eric@anholt.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1322 Lines: 32 The incoming mode might have a missing vrefresh field if it came from drmModeSetCrtc(), which the kernel is supposed to calculate using drm_mode_vrefresh(). We could either use that or the adjusted_mode's original vrefresh value. However, we can maintain a more exact vrefresh value (not just the integer approximation), by scaling by the ratio of our clocks. v2: Use math suggested by Andrzej Hajda instead. v3: Simplify math now that adjusted_mode->clock isn't padded. Signed-off-by: Eric Anholt --- drivers/gpu/drm/vc4/vc4_dsi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c index eb787eed8abe..2516cd3a1d87 100644 --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -862,7 +862,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, adjusted_mode->clock = pixel_clock_hz / 1000; /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); + adjusted_mode->htotal = (adjusted_mode->clock * mode->htotal / + mode->clock); adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal; -- 2.14.1