From patchwork Mon Jun 11 20:02:55 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= X-Patchwork-Id: 10458771 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6E6096020F for ; Mon, 11 Jun 2018 20:03:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5BEC9285C5 for ; Mon, 11 Jun 2018 20:03:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 503F6285C7; Mon, 11 Jun 2018 20:03:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 03CCE285C5 for ; Mon, 11 Jun 2018 20:03:08 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1C6A46E3B5; Mon, 11 Jun 2018 20:03:08 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8DD096E3B5 for ; Mon, 11 Jun 2018 20:03:07 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2018 13:03:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,211,1526367600"; d="scan'208";a="63695445" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.174]) by orsmga001.jf.intel.com with SMTP; 11 Jun 2018 13:02:59 -0700 Received: by stinkbox (sSMTP sendmail emulation); Mon, 11 Jun 2018 23:02:58 +0300 From: Ville Syrjala To: intel-gfx@lists.freedesktop.org Date: Mon, 11 Jun 2018 23:02:55 +0300 Message-Id: <20180611200258.27121-1-ville.syrjala@linux.intel.com> X-Mailer: git-send-email 2.16.4 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 1/4] drm/i915: Fix PIPESTATE irq ack on i965/g4x X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stable@vger.kernel.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP From: Ville Syrjälä On i965/g4x IIR is edge triggered. So in order for IIR to notice that there is still a pending interrupt we have to force and edge in ISR. For the ISR/IIR pipe event bits we can do that by temporarily clearing all the PIPESTAT enable bits when we ack the status bits. This will force the ISR pipe event bit low, and it can then go back high when we restore the PIPESTAT enable bits. This avoids the following race: 1. stat = read(PIPESTAT) 2. an enabled PIPESTAT status bit goes high 3. write(PIPESTAT, enable|stat); 4. write(IIR, PIPE_EVENT) The end result is IIR==0 and ISR!=0. This can lead to nasty vblank wait/flip_done timeouts if another interrupt source doesn't trick us into looking at the PIPESTAT status bits despite the IIR PIPE_EVENT bit being low. Before i965 IIR was level triggered so this problem can't actually happen there. And curiously VLV/CHV went back to the level triggered scheme as well. But for simplicity we'll use the same i965/g4x compatible code for all platforms. Cc: stable@vger.kernel.org Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106033 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105225 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106030 Signed-off-by: Ville Syrjälä Reviewed-by: Chris Wilson --- drivers/gpu/drm/i915/i915_irq.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 2fd92a886789..364e1c85315e 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1893,9 +1893,17 @@ static void i9xx_pipestat_irq_ack(struct drm_i915_private *dev_priv, /* * Clear the PIPE*STAT regs before the IIR + * + * Toggle the enable bits to make sure we get an + * edge in the ISR pipe event bit if we don't clear + * all the enabled status bits. Otherwise the edge + * triggered IIR on i965/g4x wouldn't notice that + * an interrupt is still pending. */ - if (pipe_stats[pipe]) - I915_WRITE(reg, enable_mask | pipe_stats[pipe]); + if (pipe_stats[pipe]) { + I915_WRITE(reg, pipe_stats[pipe]); + I915_WRITE(reg, enable_mask); + } } spin_unlock(&dev_priv->irq_lock); }