From patchwork Thu Nov 30 11:35:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Coelho X-Patchwork-Id: 13474260 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7B4B8C4167B for ; Thu, 30 Nov 2023 11:35:25 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0CD1710E6E0; Thu, 30 Nov 2023 11:35:25 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) by gabe.freedesktop.org (Postfix) with ESMTPS id AE69310E6E4; Thu, 30 Nov 2023 11:35:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701344124; x=1732880124; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=8j3k9V3ij+DNfcZXh7xDix4C/OTMUFDMdhm5NaSWbLA=; b=Tp2dXAmbgO4atczu3i3FrujB/IsYhIMmLbB7/lH3hVrK2bDnEMmlKTwX 0l4zJ5MfqPJyj/oesJjhO7hzy6KEkDu+DGqEYKzNiEZw4muhsQD6UhKiX gLhpCywhbvFW38V4/aCSg2MyTYuGF9XEo3pwaOwr1TkTMlECFxkqdUTJX SBDQQqJfXnHQGhC4UPfAKLJbFOfJ9RBL98fABSWiKRlPgohGnY1nR6Gjb Sx9MlqTHppxCpR9QFp2gEaciOwDyVZuMz3zm438c74KnuiKrsbkaI7vQD r+MuaBsyMCSyPQekeAHtM6JaNwjWhmPiVsKCF0vBpBI/F7+ekmGZaCld6 g==; X-IronPort-AV: E=McAfee;i="6600,9927,10909"; a="14861508" X-IronPort-AV: E=Sophos;i="6.04,237,1695711600"; d="scan'208";a="14861508" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Nov 2023 03:35:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10909"; a="745604704" X-IronPort-AV: E=Sophos;i="6.04,237,1695711600"; d="scan'208";a="745604704" Received: from avandeve-mobl1.amr.corp.intel.com (HELO hazy.ger.corp.intel.com) ([10.252.59.111]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Nov 2023 03:35:21 -0800 From: Luca Coelho To: intel-gfx@lists.freedesktop.org Date: Thu, 30 Nov 2023 13:35:05 +0200 Message-Id: <20231130113505.1321348-1-luciano.coelho@intel.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v6] drm/i915: handle uncore spinlock when not available X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-xe@lists.freedesktop.org, rodrigo.vivi@intel.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The uncore code may not always be available (e.g. when we build the display code with Xe), so we can't always rely on having the uncore's spinlock. To handle this, split the spin_lock/unlock_irqsave/restore() into spin_lock/unlock() followed by a call to local_irq_save/restore() and create wrapper functions for locking and unlocking the uncore's spinlock. In these functions, we have a condition check and only actually try to lock/unlock the spinlock when I915 is defined, and thus uncore is available. This keeps the ifdefs contained in these new functions and all such logic inside the display code. Cc: Tvrtko Ursulin Cc: Jani Nikula Cc: Ville Syrjala Reviewed-by: Rodrigo Vivi Signed-off-by: Luca Coelho --- In v2: * Renamed uncore_spin_*() to intel_spin_*() * Corrected the order: save, lock, unlock, restore In v3: * Undid the change to pass drm_i915_private instead of the lock itself, since we would have to include i915_drv.h and that pulls in a truckload of other includes. In v4: * After a brief attempt to replace this with a different patch, we're back to this one; * Pass drm_i195_private again, and move the functions to intel_vblank.c, so we don't need to include i915_drv.h in a header file and it's already included in intel_vblank.c; In v5: * Remove stray include in intel_display.h; * Remove unnecessary inline modifiers in the new functions. In v6: * Just removed the umlauts from Ville's name, because patchwork didn't catch my patch and I suspect it was some UTF-8 confusion. drivers/gpu/drm/i915/display/intel_vblank.c | 49 ++++++++++++++++----- 1 file changed, 39 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c index 2cec2abf9746..221fcd6bf77b 100644 --- a/drivers/gpu/drm/i915/display/intel_vblank.c +++ b/drivers/gpu/drm/i915/display/intel_vblank.c @@ -265,6 +265,30 @@ int intel_crtc_scanline_to_hw(struct intel_crtc *crtc, int scanline) return (scanline + vtotal - crtc->scanline_offset) % vtotal; } +/* + * The uncore version of the spin lock functions is used to decide + * whether we need to lock the uncore lock or not. This is only + * needed in i915, not in Xe. + * + * This lock in i915 is needed because some old platforms (at least + * IVB and possibly HSW as well), which are not supported in Xe, need + * all register accesses to the same cacheline to be serialized, + * otherwise they may hang. + */ +static void intel_vblank_section_enter(struct drm_i915_private *i915) +{ +#ifdef I915 + spin_lock(&i915->uncore.lock); +#endif +} + +static void intel_vblank_section_exit(struct drm_i915_private *i915) +{ +#ifdef I915 + spin_unlock(&i915->uncore.lock); +#endif +} + static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, bool in_vblank_irq, int *vpos, int *hpos, @@ -302,11 +326,12 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, } /* - * Lock uncore.lock, as we will do multiple timing critical raw - * register reads, potentially with preemption disabled, so the - * following code must not block on uncore.lock. + * Enter vblank critical section, as we will do multiple + * timing critical raw register reads, potentially with + * preemption disabled, so the following code must not block. */ - spin_lock_irqsave(&dev_priv->uncore.lock, irqflags); + local_irq_save(irqflags); + intel_vblank_section_enter(dev_priv); /* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */ @@ -374,7 +399,8 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ - spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); + intel_vblank_section_exit(dev_priv); + local_irq_restore(irqflags); /* * While in vblank, position will be negative @@ -412,9 +438,13 @@ int intel_get_crtc_scanline(struct intel_crtc *crtc) unsigned long irqflags; int position; - spin_lock_irqsave(&dev_priv->uncore.lock, irqflags); + local_irq_save(irqflags); + intel_vblank_section_enter(dev_priv); + position = __intel_get_crtc_scanline(crtc); - spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); + + intel_vblank_section_exit(dev_priv); + local_irq_restore(irqflags); return position; } @@ -537,7 +567,7 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, * Need to audit everything to make sure it's safe. */ spin_lock_irqsave(&i915->drm.vblank_time_lock, irqflags); - spin_lock(&i915->uncore.lock); + intel_vblank_section_enter(i915); drm_calc_timestamping_constants(&crtc->base, &adjusted_mode); @@ -546,7 +576,6 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, crtc->mode_flags = mode_flags; crtc->scanline_offset = intel_crtc_scanline_offset(crtc_state); - - spin_unlock(&i915->uncore.lock); + intel_vblank_section_exit(i915); spin_unlock_irqrestore(&i915->drm.vblank_time_lock, irqflags); }