From patchwork Thu Oct 21 15:07:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen Naidu X-Patchwork-Id: 12575467 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 F06D7C433F5 for ; Thu, 21 Oct 2021 15:11:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5CF260F9F for ; Thu, 21 Oct 2021 15:11:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231640AbhJUPNd (ORCPT ); Thu, 21 Oct 2021 11:13:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231520AbhJUPNa (ORCPT ); Thu, 21 Oct 2021 11:13:30 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32110C0613B9; Thu, 21 Oct 2021 08:11:14 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id oa12-20020a17090b1bcc00b0019f715462a8so770357pjb.3; Thu, 21 Oct 2021 08:11:14 -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=H4WUq0TumzKIrsU3f7we9d8X7+IyqHU4jplezDVQHUebClWZ8Sfpfw9LhKAHVGUsAi jHdjcN+5HCh2rqngRQoWC08Yg1wzbLuwqNLntQctfnqRMjj84sMt4cnpDBhiya0mOSEK jJ7p/uNIEs1enX2Vp1dnjSCHqw4lsmA4lVyPLqvGe1g8YDkY14sItHlIE2kKpn8OU23n MV4axwNg8ldJVAh9ymaosTErkjbiQqrotMDu/udwIJ+sYyt+TIbpzsUpfYIro6mYrHC7 CCD8JTLqjNaM7/CIxHUaM+XE3EWvWb3rg1uD+nS/ECKyDut6aF1cawI+x3+5LTEDWMoH mFhg== 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=jb2w6ZD4ywfQ+G25yZRsN9wK6Z2jXv8S5gVTCLCervdrmnw5zFUSO/frzk+3mrXmvO IFvkmPv8/kAelsCfEVDBEOpQXU6YEVny7e938krveXkzluYI7krtrmf0kZXx5qcS/UKI aLa+7qY6+MaMW+/Ppd/ArSwKokKShejVriuJweUVnAzRaDPv2HDZR3ZnPY1d4m+YrFue GwzMLmh4xh70R54ooQlHg/O98Ztk/lvqNPT+eGjYuubOhZiKjWGbHhElt4DKFq6nZxzZ X253Fu6leBwLBEzzC3VZ01J5V4+BJn1xkA6k/0SrtCfl68JUmrTX951YsYy2DyxklI6U y09w== X-Gm-Message-State: AOAM531k7QEzSsm7+RJu+BbeHFtfVQmbYzDVRVZeI2XuTZvL7lrJx8Ci DtkEvPXSNSd1Y0LnzjVbeq0= X-Google-Smtp-Source: ABdhPJxw6qmA4H9CuGRZSM2OTsKwx51IquIR23m9cD6LZfrtpp5Q60JEsUQ6WsWkmRkbHW74buIRmg== X-Received: by 2002:a17:902:aa02:b0:13a:6c8f:407f with SMTP id be2-20020a170902aa0200b0013a6c8f407fmr5543484plb.59.1634829073661; Thu, 21 Oct 2021 08:11:13 -0700 (PDT) Received: from localhost.localdomain ([2406:7400:63:29a4:d874:a949:6890:f95f]) by smtp.gmail.com with ESMTPSA id c9sm5508027pgq.58.2021.10.21.08.11.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Oct 2021 08:11:13 -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, skhan@linuxfoundation.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 v3 08/25] PCI: exynos: Remove redundant error fabrication when device read fails Date: Thu, 21 Oct 2021 20:37:33 +0530 Message-Id: <397cccc97eadc2a21924457e7ab8be1800bcb0c2.1634825082.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-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;