From patchwork Thu Nov 18 14:03:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen Naidu X-Patchwork-Id: 12627129 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 981E0C433F5 for ; Thu, 18 Nov 2021 14:06:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 818DC60EFD for ; Thu, 18 Nov 2021 14:06:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232359AbhKROJA (ORCPT ); Thu, 18 Nov 2021 09:09:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232358AbhKROJA (ORCPT ); Thu, 18 Nov 2021 09:09:00 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47CDCC061570; Thu, 18 Nov 2021 06:06:00 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id k4so5310213plx.8; Thu, 18 Nov 2021 06:06:00 -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=MJKYZ0DmEpP1c+Cyc4zstBHahVie6foEwa+j6qM9UhA=; b=jR4j+uWajdUBW8ioVx4f5AGVPE7plrg5Zo34hJRLJitbZCha37QIAEH8v3C2MoJa7L q5wQ/GZsXlkwhuooU5p0AbAlaFsADi6OUHnZsNN0WnvMrj6hC6uvKz8BX1vW1VuX64VR VTrlRCt4jn5QRUohdQMSMtX1OifQ1IZnPX7w+5MyfhrI1JMAd4mjkd2C8nmmPK0L7UPF f2YNQcjanKRL62xIjI+ejIjkPwS1WNldYOfy1AQukRqjRNKSndUpwb9Mb/9Ot4hEXnJH Pp6a8QIVJs25PViapKLN86m1IC+q/kZSX+IZfMehrG1tO9WDiiLbBnlnELHSAgcCwOYU TKag== 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=OS5C6l6yfk2MlES0BGsARAi25JdYyI4LoQcjSK9Y2hjDM0TYu3SkLNYb0kI9HKAbv4 vT07oCexBLj9JD8PpjYTuCh1YFKX1KUntQ5lmp/3jXjEGzhBfsSIxR8wbP4eG05GZGHC h6K517sPmVfVKPO8tkoumJN6xcvhAT9Ji9EZzU6PqqYnFeT0Im0QDbJUKYnj1VrxPmrg WmN2smc59sKa1FXhrbmbRhW4ighdSteO4EyLe+ksaFsl2jQMeDOQxFHItuQj0khVWE8l rnIEZFjJsiA/Ul5sX1fhD4oKh46MxQvmLniqp+lKlzElZEjrEK1tslcbDDiVZ/tLGklH gyFA== X-Gm-Message-State: AOAM5313lfkPvRCcMvOlGN7mN395XMVP+NtwlwIkTAlion3an/HYyrl+ SewI9+5++0zEHvq5YbWt+VM= X-Google-Smtp-Source: ABdhPJzzq68/X527KYUYiq6BXWx7Pi6UkM26Xbb7lDccllJj01D67EBk5gsrY3Egw/rUWXJ/CLdhdA== X-Received: by 2002:a17:90a:1f45:: with SMTP id y5mr11000237pjy.138.1637244359702; Thu, 18 Nov 2021 06:05:59 -0800 (PST) Received: from localhost.localdomain ([2406:7400:63:2c47:5ffe:fc34:61f0:f1ea]) by smtp.gmail.com with ESMTPSA id x14sm2822878pjl.27.2021.11.18.06.05.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Nov 2021 06:05:59 -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, 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 v4 08/25] PCI: exynos: Remove redundant error fabrication when device read fails Date: Thu, 18 Nov 2021 19:33:18 +0530 Message-Id: <765c2f27d85fcee4eb137023dc0a8f864eee9e36.1637243717.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-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;