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envelope-from=gerhard@engleder-embedded.com; receiver= Received: from mx10lb.world4you.com (mx10lb.world4you.com [81.19.149.120]) by smtp4.osuosl.org (Postfix) with ESMTPS id 026F340811 for ; Fri, 11 Oct 2024 20:25:01 +0000 (UTC) Received: from [88.117.56.173] (helo=hornet.engleder.at) by mx10lb.world4you.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1szLiQ-000000005uk-0ndw; Fri, 11 Oct 2024 21:54:22 +0200 From: Gerhard Engleder To: anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Date: Fri, 11 Oct 2024 21:54:12 +0200 Message-Id: <20241011195412.51804-1-gerhard@engleder-embedded.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-AV-Do-Run: Yes X-ACL-Warn: X-W4Y-Internal X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=engleder-embedded.com; s=dkim11; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=ALLXedTczsskWYT8EyWguub+TKfvEY+dZAtEEz5BF6A=; b=tmFZL+Mdx2UCrMPSH5SSONiv7C Wun4H9fmG2lzNzLGYknVliPJ7j8auJhJwzz7Vv3osQVtSqUCevRQbb6VaG+xB9qQ3+0nQdx8HA7rR rYu6P87NnnLjdupiwra907grmj4ub/yamTTGIRkH7RaaOXGL/bLCPaM3rZxebXXS30RE=; X-Mailman-Original-Authentication-Results: smtp4.osuosl.org; dmarc=pass (p=none dis=none) header.from=engleder-embedded.com X-Mailman-Original-Authentication-Results: smtp4.osuosl.org; dkim=pass (1024-bit key, unprotected) header.d=engleder-embedded.com header.i=@engleder-embedded.com header.a=rsa-sha256 header.s=dkim11 header.b=tmFZL+Md Subject: [Intel-wired-lan] [PATCH RFC net-next] e1000e: Fix real-time violations on link up X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gerhard Engleder , netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org, Gerhard Engleder Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" From: Gerhard Engleder Link down and up triggers update of MTA table. This update executes many PCIe writes and a final flush. Thus, PCIe will be blocked until all writes are flushed. As a result, DMA transfers of other targets suffer from delay in the range of 50us. The result are timing violations on real-time systems during link down and up of e1000e. Execute a flush after every single write. This prevents overloading the interconnect with posted writes. As this also increases the time spent for MTA table update considerable this change is limited to PREEMPT_RT. Signed-off-by: Gerhard Engleder --- drivers/net/ethernet/intel/e1000e/mac.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/e1000e/mac.c b/drivers/net/ethernet/intel/e1000e/mac.c index d7df2a0ed629..f4693d355886 100644 --- a/drivers/net/ethernet/intel/e1000e/mac.c +++ b/drivers/net/ethernet/intel/e1000e/mac.c @@ -331,9 +331,15 @@ void e1000e_update_mc_addr_list_generic(struct e1000_hw *hw, } /* replace the entire MTA table */ - for (i = hw->mac.mta_reg_count - 1; i >= 0; i--) + for (i = hw->mac.mta_reg_count - 1; i >= 0; i--) { E1000_WRITE_REG_ARRAY(hw, E1000_MTA, i, hw->mac.mta_shadow[i]); +#ifdef CONFIG_PREEMPT_RT + e1e_flush(); +#endif + } +#ifndef CONFIG_PREEMPT_RT e1e_flush(); +#endif } /**