From mboxrd@z Thu Jan 1 00:00:00 1970 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 93603E743F9 for ; Fri, 29 Sep 2023 08:40:22 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3581C10E6DE; Fri, 29 Sep 2023 08:40:20 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id B1EAC10E6DC; Fri, 29 Sep 2023 08:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1695976817; x=1727512817; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=EbLaPvxJrAyVGiU2du4lKUNw/vacEQgskxs2ohyuvb4=; b=c2Tbxxn57DNp9y4mzeUv6PcmuARumAnP0o6MecnQML3HXyyA41B1jPNf 1WkNLNpKQN/F+FCUx6KoFkFtWBdWOZ+Etnu9aaKpVunt3Ggu5qTyaD5JX t3+eEqeWO1EtYKXtjygx9eK1uOXvcHIjmboAqCoF15lNYblQIrh92Alge sOy3ao5Wkks4rOXLAV8DnHtPP15TFVyWxKc+P8hFLkpxI8k7u4nzEhe9p Y9Tx8onFV/5NmLsWE6UA6jgzvLfSWbTatVmtKySFvXWxQx4CQ9HEx5nXI FmzLnq2HI9umGfp8OBiLuSMZVN3F1uyWeLmlkFrJ9q39IR7ZNLbZI5MkK g==; X-IronPort-AV: E=McAfee;i="6600,9927,10847"; a="372611822" X-IronPort-AV: E=Sophos;i="6.03,186,1694761200"; d="scan'208";a="372611822" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 01:40:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10847"; a="699575884" X-IronPort-AV: E=Sophos;i="6.03,186,1694761200"; d="scan'208";a="699575884" Received: from nirmoyda-mobl.ger.corp.intel.com (HELO [10.252.39.203]) ([10.252.39.203]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 01:40:15 -0700 Message-ID: <04e38c7b-3acc-1f5c-7b7a-aba0ef701b84@linux.intel.com> Date: Fri, 29 Sep 2023 10:40:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Content-Language: en-US To: Andrzej Hajda , Nirmoy Das , intel-gfx@lists.freedesktop.org References: <20230928130015.6758-1-nirmoy.das@intel.com> From: Nirmoy Das In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Intel-gfx] [PATCH v7 1/4] drm/i915: Introduce intel_gt_mcr_lock_sanitize() 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: matthew.d.roper@intel.com, dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 9/28/2023 11:42 PM, Andrzej Hajda wrote: > On 28.09.2023 15:00, Nirmoy Das wrote: >> Implement intel_gt_mcr_lock_sanitize() to provide a mechanism >> for cleaning the steer semaphore when absolutely necessary. >> >> v2: remove unnecessary lock(Andi, Matt) >>      improve the kernel doc(Matt) >>      s/intel_gt_mcr_lock_clear/intel_gt_mcr_lock_sanitize >> >> Signed-off-by: Nirmoy Das >> --- >>   drivers/gpu/drm/i915/gt/intel_gt_mcr.c | 22 ++++++++++++++++++++++ >>   drivers/gpu/drm/i915/gt/intel_gt_mcr.h |  1 + >>   2 files changed, 23 insertions(+) >> >> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c >> b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c >> index bf4a933de03a..326c2ed1d99b 100644 >> --- a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c >> +++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c >> @@ -419,6 +419,28 @@ void intel_gt_mcr_unlock(struct intel_gt *gt, >> unsigned long flags) >>           intel_uncore_write_fw(gt->uncore, MTL_STEER_SEMAPHORE, 0x1); >>   } >>   +/** >> + * intel_gt_mcr_lock_sanitize - Sanitize MCR steering lock >> + * @gt: GT structure >> + * >> + * This will be used to sanitize the initial status of the hardware >> lock >> + * during driver load and resume since there won't be any concurrent >> access >> + * from other agents at those times, but it's possible that boot >> firmware >> + * may have left the lock in a bad state. >> + * >> + */ >> +void intel_gt_mcr_lock_sanitize(struct intel_gt *gt) >> +{ >> +    /* >> +     * This gets called at load/resume time, so we shouldn't be >> +     * racing with other driver threads grabbing the mcr lock. >> +     */ >> +    lockdep_assert_not_held(>->mcr_lock); >> + >> +    if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) >> +        intel_uncore_write_fw(gt->uncore, MTL_STEER_SEMAPHORE, 0x1); > > I wonder if it wouldn't be useful to check and report if it is locked > before unconditional release, no strong feelings. Not so useful for user but may be as debug log if we need. > > Reviewed-by: Andrzej Hajda Thanks, Nirmoy > > Regards > Andrzej > > >> +} >> + >>   /** >>    * intel_gt_mcr_read - read a specific instance of an MCR register >>    * @gt: GT structure >> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.h >> b/drivers/gpu/drm/i915/gt/intel_gt_mcr.h >> index 41684495b7da..01ac565a56a4 100644 >> --- a/drivers/gpu/drm/i915/gt/intel_gt_mcr.h >> +++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.h >> @@ -11,6 +11,7 @@ >>   void intel_gt_mcr_init(struct intel_gt *gt); >>   void intel_gt_mcr_lock(struct intel_gt *gt, unsigned long *flags); >>   void intel_gt_mcr_unlock(struct intel_gt *gt, unsigned long flags); >> +void intel_gt_mcr_lock_sanitize(struct intel_gt *gt); >>     u32 intel_gt_mcr_read(struct intel_gt *gt, >>                 i915_mcr_reg_t reg, >