From patchwork Thu Nov 18 14:03:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Naveen Naidu X-Patchwork-Id: 12627109 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 AE9C1C433FE for ; Thu, 18 Nov 2021 14:06:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 987C461AE2 for ; Thu, 18 Nov 2021 14:06:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232378AbhKROJo (ORCPT ); Thu, 18 Nov 2021 09:09:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232300AbhKROJo (ORCPT ); Thu, 18 Nov 2021 09:09:44 -0500 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 20C76C061570; Thu, 18 Nov 2021 06:06:44 -0800 (PST) Received: by mail-pf1-x42b.google.com with SMTP id z6so6101143pfe.7; Thu, 18 Nov 2021 06:06:44 -0800 (PST) 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=n/yt+ar9LeJXp+LgPRjnz08fHYE7Y6D7uP8N5v1qSeQ=; b=ju5IgyBkawORLGdE5+lvjqmVMlAJUBHJQunyAtZAHZeDq2OXPFfbOCXZ/z6XcreEmd 8Gb5fyu/w7VxIygaGX06SKEUiejhTJb+VroQuBSLQUew7HaeAiJfxxhAxBh34f7i2HVA zZM8dL5hfTR+iWHlqmLBHG8qMmBc0uN9ZJv4QqsaMEP4gN5rV+7WFHhuoQqxkXQmhCNL d23U7KjYdmtAVrH8eLX9VAmblo3HQd9kc60htoY0gkWIRoKbUOclN4VQnRhKvWgB+EUG 7fMw/n104iCAB9CKf0WenkQ88x3KHJfrQwgovVliRSHPm22klNnEiPbspoDUXf++2rH7 C6PQ== 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=n/yt+ar9LeJXp+LgPRjnz08fHYE7Y6D7uP8N5v1qSeQ=; b=SgVzyLy/ue4UUFfuf/ZFyx/HQ/xJ8G9m4XAWqZEgSgSwzBTWNu/8b72ji0x5S7k9qK 4h68KH4PXks4ctPb0Ud7YDa0O/awqW34UTDs2gIwKgBejqoiinnZg2TFXyPc6CNY67F7 f8FIkSMuRXnwtKClR9QvgS2Zsic3MGROU6FvLW+ztrZ9iFEE+2rzCnsYFnkTVLGVS7/q vKVBI8Q/2IZ7PKWNbByMYh/dYGg+q0BGC57OF8fOzsEke4VVvwWJSrnrUf7bq1e+/jDB Q23NNbC+PJdHeFAy2ruej9OMBAFmQaOpM1IWZXl5VZi9eKeKvg81EQ5Y/pTvwYc47MbT YzNg== X-Gm-Message-State: AOAM533M7awL05kJEQkjU+kUIOAA5FF39GWdTNSTWzyM3AtFXMQDWhrq JgIHPjebyoZDLu40nhiOVSA= X-Google-Smtp-Source: ABdhPJwRC2+Zew+d+pDpceltjCbSl2htV5tAPVKvoWCpsnfdWeC89UX5XOOHSvDvVdy5CjvvBZKwLg== X-Received: by 2002:a05:6a00:2283:b0:49f:dea0:b9ba with SMTP id f3-20020a056a00228300b0049fdea0b9bamr15379492pfe.56.1637244403560; Thu, 18 Nov 2021 06:06:43 -0800 (PST) Received: from localhost.localdomain ([2406:7400:63:2c47:5ffe:fc34:61f0:f1ea]) by smtp.gmail.com with ESMTPSA id x14sm2822878pjl.27.2021.11.18.06.06.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Nov 2021 06:06:43 -0800 (PST) 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, skhan@linuxfoundation.org, =?utf-8?q?Pali_Roh?= =?utf-8?q?=C3=A1r?= , Thomas Petazzoni , Lorenzo Pieralisi , Rob Herring , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , linux-arm-kernel@lists.infradead.org (moderated list:PCI DRIVER FOR AARDVARK (Marvell Armada 3700)) Subject: [PATCH v4 11/25] PCI: aardvark: Remove redundant error fabrication when device read fails Date: Thu, 18 Nov 2021 19:33:21 +0530 Message-Id: <335014f2b44cdf24ed1e37cb7c88f6c5de896cc2.1637243717.git.naveennaidu479@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@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. Reviewed-by: Pali Rohár Signed-off-by: Naveen Naidu --- drivers/pci/controller/pci-aardvark.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index c5300d49807a..1de41d2c9b44 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -1026,10 +1026,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, u32 reg; int ret; - if (!advk_pcie_valid_device(pcie, bus, devfn)) { - *val = 0xffffffff; + if (!advk_pcie_valid_device(pcie, bus, devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } if (pci_is_root_bus(bus)) return pci_bridge_emul_conf_read(&pcie->bridge, where,