From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967055AbdADJas (ORCPT ); Wed, 4 Jan 2017 04:30:48 -0500 Received: from lelnx193.ext.ti.com ([198.47.27.77]:31525 "EHLO lelnx193.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758561AbdADJar (ORCPT ); Wed, 4 Jan 2017 04:30:47 -0500 Subject: Re: [PATCH v2] drm: tilcdc: simplify the recovery from sync lost error on rev1 To: Bartosz Golaszewski , Tomi Valkeinen , David Airlie , Kevin Hilman , Michael Turquette , Sekhar Nori References: <1482158834-29477-1-git-send-email-bgolaszewski@baylibre.com> CC: LKML , linux-drm , Peter Ujfalusi , arm-soc From: Jyri Sarha Message-ID: <8282435c-7ee4-61bd-8399-4c58a9fc5279@ti.com> Date: Wed, 4 Jan 2017 11:29:46 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <1482158834-29477-1-git-send-email-bgolaszewski@baylibre.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19/16 16:47, Bartosz Golaszewski wrote: > 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 After testing I'll send this as fixes pull req for tilcdc 4.10. Reviewed-by: Jyri Sarha > --- > 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; > + } > } > } > >