From patchwork Fri Oct 15 14:38:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen Naidu X-Patchwork-Id: 12562219 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FD2BC433EF for ; Fri, 15 Oct 2021 14:44:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8F0061041 for ; Fri, 15 Oct 2021 14:44:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240644AbhJOOqM (ORCPT ); Fri, 15 Oct 2021 10:46:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240633AbhJOOqJ (ORCPT ); Fri, 15 Oct 2021 10:46:09 -0400 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ACAD2C061762; Fri, 15 Oct 2021 07:44:02 -0700 (PDT) Received: by mail-pj1-x102f.google.com with SMTP id d13-20020a17090ad3cd00b0019e746f7bd4so9521546pjw.0; Fri, 15 Oct 2021 07:44:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=MJKYZ0DmEpP1c+Cyc4zstBHahVie6foEwa+j6qM9UhA=; b=PB5yktV/ub7HqC20LufS0j08yKPnVALPVgzyvDwsxvrVrVcQixB/EB6YPc+JIMu+ar yoENAo4stX/Y6X2yBLrRWo9YWjJo+AQ/CGhVh88rXCrlyusLG8mADi0TLW37tnEKWKXV ZDZPwyHP+DjuY+La534/Rdb5RXEzZbdjDEIm+dCCMLyFbDYkAIgwBL5eMIPKLynktEv+ MdPiMm9RTNI6/inp3ScRrGDXxmyNbkqwmS+l0+X2OrlW716XPJ1Hjxx7rdbjEFzyAwk9 HI20wPgr7JmeLpb5drVfenrAS1th9QPRhhpk/XKcsO9mRK0pM5FXtTrqOBdZAKk1cSjy tm1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=MJKYZ0DmEpP1c+Cyc4zstBHahVie6foEwa+j6qM9UhA=; b=sXYq5jAEG1uPt0p3VPm6eJ/7OokPp/agOpPud5D1eY/21gQVPTxAJZiRc0ISfRpW6I Q4SXrNyZ8Cd8rwvcSo/R7sZN7upyR5+UYJt20hpYdqU1lQRC4qJ9C0Ixtj5+YEqMBFkr mX+6CrUKOLjoswoYNLJVyG2OXeg8emBIgZs5ehHsjBLseU8zEytFFMZ/f2a/1+9YWQz0 NIKhbnb0+T7/Gf3f0L+EFjAlAZ4EX/uKZerMg08KDNsIW9p7fdHXnp/rB94eXMKYH72j ESmmTVh7kA0bjd92fjvVVNQzbRqme3lCDVAebHUPh+4F4MpI/GNbn7D59Bo/mTPV7Yw5 i48w== X-Gm-Message-State: AOAM531PNFXw8/te6ZTN77QolRK/BfqYVDUL2s6wyFQ3zi+WEat9vEmI e9opM/j0lQQMujulZR/sz48= X-Google-Smtp-Source: ABdhPJwFF4cjJO6JehPcfRawKHCZyqAMPX+66Ii/ds5YGW7OM7k+bLu2mTJzx+lW8crVIAUkT/oqmg== X-Received: by 2002:a17:90b:1644:: with SMTP id il4mr28408623pjb.179.1634309042196; Fri, 15 Oct 2021 07:44:02 -0700 (PDT) Received: from localhost.localdomain ([2406:7400:63:4806:9a51:7f4b:9b5c:337a]) by smtp.gmail.com with ESMTPSA id f18sm5293491pfa.60.2021.10.15.07.43.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Oct 2021 07:44:01 -0700 (PDT) From: Naveen Naidu To: bhelgaas@google.com Cc: Naveen Naidu , linux-kernel-mentees@lists.linuxfoundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Jingoo Han , Lorenzo Pieralisi , Rob Herring , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org (moderated list:PCI DRIVER FOR SAMSUNG EXYNOS), linux-samsung-soc@vger.kernel.org (open list:PCI DRIVER FOR SAMSUNG EXYNOS) Subject: [PATCH v2 08/24] PCI: exynos: Remove redundant error fabrication when device read fails Date: Fri, 15 Oct 2021 20:08:49 +0530 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org An MMIO read from a PCI device that doesn't exist or doesn't respond causes a PCI error. There's no real data to return to satisfy the CPU read, so most hardware fabricates ~0 data. The host controller drivers sets the error response values (~0) and returns an error when faulty hardware read occurs. But the error response value (~0) is already being set in PCI_OP_READ and PCI_USER_READ_CONFIG whenever a read by host controller driver fails. Thus, it's no longer necessary for the host controller drivers to fabricate any error response. This helps unify PCI error response checking and make error check consistent and easier to find. Signed-off-by: Naveen Naidu --- drivers/pci/controller/dwc/pci-exynos.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/dwc/pci-exynos.c b/drivers/pci/controller/dwc/pci-exynos.c index c24dab383654..f9526d6de160 100644 --- a/drivers/pci/controller/dwc/pci-exynos.c +++ b/drivers/pci/controller/dwc/pci-exynos.c @@ -216,10 +216,8 @@ static int exynos_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn, { struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata); - if (PCI_SLOT(devfn)) { - *val = ~0; + if (PCI_SLOT(devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } *val = dw_pcie_read_dbi(pci, where, size); return PCIBIOS_SUCCESSFUL;