Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762162AbcLSOrb (ORCPT ); Mon, 19 Dec 2016 09:47:31 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:36971 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbcLSOrU (ORCPT ); Mon, 19 Dec 2016 09:47:20 -0500 From: Bartosz Golaszewski To: Jyri Sarha , Tomi Valkeinen , David Airlie , Kevin Hilman , Michael Turquette , Sekhar Nori Cc: LKML , linux-drm , Peter Ujfalusi , arm-soc , Bartosz Golaszewski Subject: [PATCH v2] drm: tilcdc: simplify the recovery from sync lost error on rev1 Date: Mon, 19 Dec 2016 15:47:14 +0100 Message-Id: <1482158834-29477-1-git-send-email-bgolaszewski@baylibre.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2517 Lines: 70 Revision 2 of LCDC suffers from an issue where a SYNC_LOST error caused by limited memory bandwidth may leave the picture shifted a couple pixels to the right. This issue has not been observed on revision 1, while the recovery mechanism introduces a different issue, where the END_OF_FRAME interrupt doesn't fire while drm is waiting for vblanks. On rev1: recover from sync lost errors by simply clearing the RASTER_ENABLE bit in the RASTER_CTRL register and re-enabling it again as is suggested by the datasheet. Signed-off-by: Bartosz Golaszewski --- v1 -> v2: - add a check to see if the RASTER_ENABLE bit is set before clearing it drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c index 9942b05..2004107 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c @@ -856,7 +856,7 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc) struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc); struct drm_device *dev = crtc->dev; struct tilcdc_drm_private *priv = dev->dev_private; - uint32_t stat; + uint32_t stat, reg; stat = tilcdc_read_irqstatus(dev); tilcdc_clear_irqstatus(dev, stat); @@ -921,17 +921,26 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc) dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost", __func__, stat); tilcdc_crtc->frame_intact = false; - if (tilcdc_crtc->sync_lost_count++ > - SYNC_LOST_COUNT_LIMIT) { - dev_err(dev->dev, "%s(0x%08x): Sync lost flood detected, recovering", __func__, stat); - queue_work(system_wq, &tilcdc_crtc->recover_work); - if (priv->rev == 1) + if (priv->rev == 1) { + reg = tilcdc_read(dev, LCDC_RASTER_CTRL_REG); + if (reg & LCDC_RASTER_ENABLE) { tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, - LCDC_V1_SYNC_LOST_INT_ENA); - else + LCDC_RASTER_ENABLE); + tilcdc_set(dev, LCDC_RASTER_CTRL_REG, + LCDC_RASTER_ENABLE); + } + } else { + if (tilcdc_crtc->sync_lost_count++ > + SYNC_LOST_COUNT_LIMIT) { + dev_err(dev->dev, + "%s(0x%08x): Sync lost flood detected, recovering", + __func__, stat); + queue_work(system_wq, + &tilcdc_crtc->recover_work); tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG, LCDC_SYNC_LOST); - tilcdc_crtc->sync_lost_count = 0; + tilcdc_crtc->sync_lost_count = 0; + } } } -- 2.9.3