From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7774EC48BC2 for ; Mon, 21 Jun 2021 18:37:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DF3660FEA for ; Mon, 21 Jun 2021 18:37:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231518AbhFUSjk (ORCPT ); Mon, 21 Jun 2021 14:39:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:36880 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231840AbhFUSjk (ORCPT ); Mon, 21 Jun 2021 14:39:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A92D56109F; Mon, 21 Jun 2021 18:37:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624300645; bh=eTTlwDkeyO67L3bvqEkV/+MwTD0Ip0/Wv5AUnA1irB0=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=dpgYbklE+Gu7BbGEB+vWxkEh6vJP7kSoxaLN9gbzCKaFYWrzk+s6qJBTy+7ubJZLv Omy8HRg6tyTJ0cp/rlfcgO94fO747RrsuSTubk5GcYOCaezkNBx86ZqOtRR8JwgGAA pHm4IXh9/vgcM1rNuueJPN39dXsELGPrPnFYGZ0hHAVlFBc+WjUlPYY3McJermwdGC hLKPNkdUE3Pk0Ir+AsPeg8VgYx7oeZX2EYcRtgdq+qK7LdlJmxOn+C/elBbWtCxgsz 9KfbwdPS10/9VjupKZqFRtMnp7FZZgjNUDcY3D2W7ExWH9plXqEBXP9FAoQsjFY8CM JvDQoOyMjp0GA== Date: Mon, 21 Jun 2021 13:37:24 -0500 From: Bjorn Helgaas To: Amey Narkhede Cc: Shanker R Donthineni , alex.williamson@redhat.com, Raphael Norwitz , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kw@linux.com, Sinan Kaya , Len Brown , "Rafael J . Wysocki" Subject: Re: [PATCH v7 2/8] PCI: Add new array for keeping track of ordering of reset methods Message-ID: <20210621183724.GA3291108@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210621171518.vs4h4y6ag2benlwp@archlinux> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Jun 21, 2021 at 10:45:18PM +0530, Amey Narkhede wrote: > On 21/06/21 10:02AM, Shanker R Donthineni wrote: > > On 6/18/21 12:22 PM, Amey Narkhede wrote: > > > I wonder if this would be easier if dev->reset_methods[] contained > > > indices into pci_reset_fn_methods[], highest priority first, with the > > > priority being determined when dev->reset_methods[] is updated. For > > > example: > > > > > > const struct pci_reset_fn_method pci_reset_fn_methods[] = { > > > { }, # 0 > > > { &pci_dev_specific_reset, .name = "device_specific" }, # 1 > > > { &pci_dev_acpi_reset, .name = "acpi" }, # 2 > > > { &pcie_reset_flr, .name = "flr" }, # 3 > > > { &pci_af_flr, .name = "af_flr" }, # 4 > > > { &pci_pm_reset, .name = "pm" }, # 5 > > > { &pci_reset_bus_function, .name = "bus" }, # 6 > > > }; > > > > > > dev->reset_methods[] = [1, 2, 3, 4, 5, 6] > > > means all reset methods are supported, in the default priority > > > order > > > > > > dev->reset_methods[] = [1, 0, 0, 0, 0, 0] > > > means only pci_dev_specific_reset is supported > > > > > > dev->reset_methods[] = [3, 5, 0, 0, 0, 0] > > > means pcie_reset_flr and pci_pm_reset are supported, in that > > > priority order > > > > What about keeping two bitmap fields 'resets_supported' and > > 'resets_enabled' in pci_dev object and mange it through sysfs and > > probe helper function. We can avoid two loops multiple paces and > > takes only 2Bytes of memory to keep track resets. > > > > resets_supported  ---> initialized during pci_dev setup > > resets_enabled ---> Exposed to userspace through sysfs by default set to resets_supported > > > > include/linux/pci.h: > > ------------------------ > > /* Different types of PCI resets possible, lower number is higher priority */ > > #define PCI_RESET_METHOD_DEVSPEC     0 > > #define PCI_RESET_METHOD_ACPI            1 > > #define PCI_RESET_METHOD_FLR              2 > > #define PCI_RESET_METHOD_Af_FLR         3 > > #define PCI_RESET_METHOD_PM               4 > > #define PCI_RESET_METHOD_BUS             5 > > #define PCI_RESET_METHOD_MAX            6 > > > > struct pci_dev { > >     ... > >         u8              resets_supported; > >         u8              resets_enabled; > > }; > > > > static inline bool pci_reset_supported(struct pci_dev *dev) > > { > >         return !!(dev->resets_supported); > > } > > > > > > drivers/pci/pci.c: > > -------------------- > > const struct pci_reset_fn_method pci_reset_fn_methods[PCI_RESET_METHOD_MAX] = { > >         [PCI_RESET_METHOD_DEVSPEC] = { &pci_dev_specific_reset, > >                                                                    .name = "device_specific" }, > >         [PCI_RESET_METHOD_ACPI] = { &pci_dev_acpi_reset, .name = "acpi" }, > >         [PCI_RESET_METHOD_FLR] = { &pcie_reset_flr, .name = "flr" }, > >         [PCI_RESET_METHOD_Af_FLR] = { &pci_af_flr, .name = "af_flr" }, > >         [PCI_RESET_METHOD_PM] = { &pci_pm_reset, .name = "pm" }, > >         [PCI_RESET_METHOD_BUS] = { &pci_reset_bus_function, .name = "bus" } > > }; > > > > > > void pci_init_reset_methods(struct pci_dev *dev) > > { > >         int i, rc; > > > >         BUILD_BUG_ON(ARRAY_SIZE(pci_reset_fn_methods) != PCI_RESET_METHOD_MAX); > >         might_sleep(); > > > >         for (i = 0; i < PCI_RESET_METHOD_MAX; i++) { > >                 rc = pci_reset_fn_methods[i].reset_fn(dev, PCI_RESET_PROBE); > >                 if (!rc) > >                         dev->resets_supported |= BIT(i); > >                 else if (rc != -ENOTTY) > >                         break; > >         } > >         dev->resets_enabled = dev->resets_supported; > > } > > > > int __pci_reset_function_locked(struct pci_dev *dev) > > { > >         int i, rc = -ENOTTY; > > > >         might_sleep(); > > > >         for (i = 0; i < PCI_RESET_METHOD_MAX; i++) { > >                 if (dev->resets_enabled & BIT(i)) { > >                         rc = pci_reset_fn_methods[i].reset_fn(dev, 0); > >                         if (rc != -ENOTTY) > >                                 return rc; > >                 } > >         } > > > >         if (rc == -ENOTTY) > >                 pci_warn(dev, "No reset happened reason %s\n", > >                          !!dev->resets_supported ? > >                          "disabled by user" : "not supported"); > > > >         return rc; > > } > > > > drivers/pci/pci-sysfs.c > > ---------------------------- > > static ssize_t reset_method_store(struct device *dev, > >                                   struct device_attribute *attr, > >                                   const char *buf, size_t count) > > { > >         struct pci_dev *pdev = to_pci_dev(dev); > >         u8 resets_enabled = 0; > > ... > >         if (sysfs_streq(options, "default")) { > >                 pdev->resets_enabled = pdev->resets_supported; > >                 goto set_reset_methods; > >         } > > > >         while ((name = strsep(&options, ",")) != NULL) { > >                 if (sysfs_streq(name, "")) > >                         continue; > >                 name = strim(name); > > > >                 for (i = 0; i < PCI_RESET_METHOD_MAX; i++) { > >                         if ((pdev->resets_supported & BIT(i)) && > >                             sysfs_streq(name, pci_reset_fn_methods[i].name)) { > >                                 resets_enabled |= BIT(i); > >                                 break; > >                         } > >                 } > > ... > >         } > > > > set_reset_methods: > >         kfree(options); > >         pdev->resets_enabled =  resets_enabled; > >         return count; > > } > > > > static ssize_t reset_method_show(struct device *dev, > >                                  struct device_attribute *attr, > >                                  char *buf) > > { > >         struct pci_dev *pdev = to_pci_dev(dev); > >         ssize_t len = 0; > >         int i; > > > >         for (i = 0; i < PCI_RESET_METHOD_MAX; i++) { > >                 if (pdev->resets_enabled & BIT(i)) > >                         len += sysfs_emit_at(buf, len, "%s%s", > >                                              len ? "," : "", > >                                              pci_reset_fn_methods[i].name); > >         } > >         len += sysfs_emit_at(buf, len, len ? "\n" : ""); > > > >         return len; > > } > > > Thank you for the idea. > Actually that would be coming full circle because Alex, Raphael and > I tried similar approach earlier while prototyping for v2 but this > implementation does look better than what I had at that time. I thought part of the point of this series was to allow the user to change the *order* of reset types. I don't think we can control the ordering if we only keep a bit (or even two) per reset type.