From patchwork Tue Apr 21 11:16:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Marek_Beh=C3=BAn?= X-Patchwork-Id: 1274170 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=nic.cz Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=nic.cz header.i=@nic.cz header.a=rsa-sha256 header.s=default header.b=P+gtIP4y; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4961HQ4x70z9sSW for ; Tue, 21 Apr 2020 21:17:06 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728654AbgDULRF (ORCPT ); Tue, 21 Apr 2020 07:17:05 -0400 Received: from mail.nic.cz ([217.31.204.67]:40748 "EHLO mail.nic.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728610AbgDULRF (ORCPT ); Tue, 21 Apr 2020 07:17:05 -0400 Received: from dellmb.labs.office.nic.cz (unknown [IPv6:2001:1488:fffe:6:cac7:3539:7f1f:463]) by mail.nic.cz (Postfix) with ESMTP id 98EEA141337; Tue, 21 Apr 2020 13:17:02 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nic.cz; s=default; t=1587467822; bh=WWdULTS/yrmI1pxEZNYpKN5Ix1wCZmr0xU/efBMkzws=; h=From:To:Date; b=P+gtIP4yAlKb6dV434lUbdneEyqVTityTaylZAxiUnA5wMFgnQ3Em6U39xDbgV3h4 rqPE/1U8s0i4j8zcbQDDSPsBVgzsmrmDCYVoR1Af+AwkifZ6+H/gxJV0IKNqJCAjCq qwXu5ef/jVZ7qGyugZ37PamWbUWz93L89Gobnl7I= From: =?utf-8?q?Marek_Beh=C3=BAn?= To: linux-pci@vger.kernel.org Cc: Jason Cooper , Andrew Lunn , Gregory Clement , Sebastian Hesselbarth , Thomas Petazzoni , Lorenzo Pieralisi , Andrew Murray , Bjorn Helgaas , Remi Pommarel , Tomasz Maciej Nowak , Xogium , =?utf-8?q?Pali_Roh=C3=A1r?= Subject: [PATCH v2 2/9] PCI: aardvark: don't write to read-only register Date: Tue, 21 Apr 2020 13:16:54 +0200 Message-Id: <20200421111701.17088-3-marek.behun@nic.cz> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200421111701.17088-1-marek.behun@nic.cz> References: <20200421111701.17088-1-marek.behun@nic.cz> MIME-Version: 1.0 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on mail.nic.cz X-Spam-Status: No, score=0.00 X-Spamd-Bar: / X-Virus-Scanned: clamav-milter 0.101.4 at mail X-Virus-Status: Clean Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Pali Rohár Trying to change Link Status register does not have any effect as this is a read-only register. Trying to overwrite bits for Negotiated Link Width does not make sense. In future proper change of link width can be done via Lane Count Select bits in PCIe Control 0 register. Trying to unconditionally enable ASPM L0s via ASPM Control bits in Link Control register is wrong. There should be at least some detection if endpoint supports L0s as isn't mandatory. Moreover ASPM Control bits in Link Control register are controlled by pcie/aspm.c code which sets it according to system ASPM settings, immediately after aardvark driver probes. So setting these bits by aardvark driver has no long running effect. Remove code which touches ASPM L0s bits from this driver and let kernel's ASPM implementation to set ASPM state properly. Some users are reporting issues that this code is problematic for some Intel wifi cards and removing it fixes them, see e.g.: https://bugzilla.kernel.org/show_bug.cgi?id=196339 If problems with Intel wifi cards occur even after this commit, then pcie/aspm.c code could be modified / hooked to not enable ASPM L0s state for affected problematic cards. Signed-off-by: Pali Rohár --- drivers/pci/controller/pci-aardvark.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index b59198a102d0..551d98174613 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -356,10 +356,6 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) advk_pcie_wait_for_link(pcie); - reg = PCIE_CORE_LINK_L0S_ENTRY | - (1 << PCIE_CORE_LINK_WIDTH_SHIFT); - advk_writel(pcie, reg, PCIE_CORE_LINK_CTRL_STAT_REG); - reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); reg |= PCIE_CORE_CMD_MEM_ACCESS_EN | PCIE_CORE_CMD_IO_ACCESS_EN |