From patchwork Wed Aug 10 06:00:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 597134 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5282AC32763 for ; Wed, 10 Aug 2022 06:01:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230419AbiHJGBa (ORCPT ); Wed, 10 Aug 2022 02:01:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231191AbiHJGBD (ORCPT ); Wed, 10 Aug 2022 02:01:03 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B77415FE8 for ; Tue, 9 Aug 2022 23:01:02 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-3230031a80fso117744467b3.5 for ; Tue, 09 Aug 2022 23:01:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc; bh=zsc6LReCkj1qjWFHoe9RU5QlsrwqzoWhqcv1gy5ixZY=; b=qAChj47DwLOrFVomS2lGpLSpKGvd1Ma7wbTL3BaBnyvNDdaT6wQcELiK3Z2S6rKmW6 4RCg3rt6j2rD/dXyIpiJAt0rXCb4GtTf9uNP6hZi708k7YPc7ZxFVW1djWMkZKngZUyC 9ZOMJL5O3k7bMThCT+oPldcDnUF4i0ommrfHppvhsYUq/eEQsh/fyoQBlUi7r5vctc/F 9u/dHFrzIRRFZvBW99iEWRVEUfrxv+VRxXw6eyDf8bHeE9dwuyd1QG8zMM9IyxoXCqpp yxsC7TNyQiZWMwjfcKw173fewjgqVWZOvnFwQB5H8vymYFjevDNXEPOljd/VGIQLMaOQ 7eew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc; bh=zsc6LReCkj1qjWFHoe9RU5QlsrwqzoWhqcv1gy5ixZY=; b=WpGz2uW5XlBdcuh5NgkW8EEcz/0SpUpV8dUULnjuLU3d5NbhLXACBnF4ZqdAhrtrn0 RKgJsWCm7gS3xDqI38BrPV52pUbYGJh/AJUkCcPiyU7cXYS9rSmc4A52nmR9BXVKQfKI QyVPQcAy1sBg8cXdkeSWKoD63nIwx3nOaeCwdYhcJijtehbChaGUv+5YSTCBjIJfpNnd 20B0G+FLEJAWEdVn+637OKN2pkAIBX/RG8bQw2fww3jpFaiODVKJk6Yj11DH+1X9vk65 WJwtYcLSC8+Eted9CZPPxFI+7G6CAle/X1CbB5+WQFYJDCunNErrIcMHa6MaJnB6LqW1 yq+A== X-Gm-Message-State: ACgBeo0YmEAknNXLDSQNrPIuB9GpY7eUkgCVCW7EkztpeYz8Pag0iY0F 27VO0X3qk0D+9jI+hd2fgsKnvQWuw64KOTk= X-Google-Smtp-Source: AA6agR7UHIfPmQyEJpTq1ANtIM/YpnjUfuF4LCqgIoVdmjpw9+J9eqTmKa2fu2A5mGFX/RbYZr7v9jvnFZ4Lhg0= X-Received: from saravanak.san.corp.google.com ([2620:15c:2d:3:f21:76ca:766f:e0ab]) (user=saravanak job=sendgmr) by 2002:a05:6902:100d:b0:67a:7141:a2bf with SMTP id w13-20020a056902100d00b0067a7141a2bfmr23586344ybt.54.1660111261905; Tue, 09 Aug 2022 23:01:01 -0700 (PDT) Date: Tue, 9 Aug 2022 23:00:34 -0700 In-Reply-To: <20220810060040.321697-1-saravanak@google.com> Message-Id: <20220810060040.321697-6-saravanak@google.com> Mime-Version: 1.0 References: <20220810060040.321697-1-saravanak@google.com> X-Mailer: git-send-email 2.37.1.559.g78731f0fdb-goog Subject: [PATCH v1 5/9] driver core: fw_devlink: Add DL_FLAG_CYCLE support to device links From: Saravana Kannan To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Linus Walleij , Bartosz Golaszewski , Rob Herring , Frank Rowand , Geert Uytterhoeven , Magnus Damm , Andy Shevchenko , Daniel Scally , Heikki Krogerus , Sakari Ailus , Len Brown Cc: Saravana Kannan , Abel Vesa , Alexander Stein , Tony Lindgren , Sudeep Holla , Geert Uytterhoeven , John Stultz , Doug Anderson , Guenter Roeck , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-acpi@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org fw_devlink uses DL_FLAG_SYNC_STATE_ONLY device link flag for two purposes: 1. To allow a parent device to proxy its child device's dependency on a supplier so that the supplier doesn't get its sync_state() callback before the child device/consumer can be added and probed. In this usage scenario, we need to ignore cycles for ensure correctness of sync_state() callbacks. 2. When there are dependency cycles in firmware, we don't know which of those dependencies are valid. So, we have to ignore them all wrt probe ordering while still making sure the sync_state() callbacks come correctly. However, when detecting dependency cycles, there can be multiple dependency cycles between two devices that we need to detect. For example: A -> B -> A and A -> C -> B -> A. To detect multiple cycles correct, we need to be able to differentiate DL_FLAG_SYNC_STATE_ONLY device links used for (1) vs (2) above. To allow this differentiation, add a DL_FLAG_CYCLE that can be use to mark use case (2). We can then use the DL_FLAG_CYCLE to decide which DL_FLAG_SYNC_STATE_ONLY device links to follow when looking for dependency cycles. Signed-off-by: Saravana Kannan --- drivers/base/core.c | 28 ++++++++++++++++++---------- include/linux/device.h | 1 + 2 files changed, 19 insertions(+), 10 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 8ec2236b1f9c..afa660d14172 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -321,6 +321,12 @@ static bool device_is_ancestor(struct device *dev, struct device *target) return false; } +static inline bool device_link_flag_is_sync_state_only(u32 flags) +{ + return (flags & ~(DL_FLAG_INFERRED | DL_FLAG_CYCLE)) + == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED); +} + /** * device_is_dependent - Check if one device depends on another one * @dev: Device to check dependencies for. @@ -347,8 +353,7 @@ int device_is_dependent(struct device *dev, void *target) return ret; list_for_each_entry(link, &dev->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (device_link_flag_is_sync_state_only(link->flags)) continue; if (link->consumer == target) @@ -421,8 +426,7 @@ static int device_reorder_to_tail(struct device *dev, void *not_used) device_for_each_child(dev, NULL, device_reorder_to_tail); list_for_each_entry(link, &dev->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (device_link_flag_is_sync_state_only(link->flags)) continue; device_reorder_to_tail(link->consumer, NULL); } @@ -683,7 +687,8 @@ postcore_initcall(devlink_class_init); DL_FLAG_AUTOREMOVE_SUPPLIER | \ DL_FLAG_AUTOPROBE_CONSUMER | \ DL_FLAG_SYNC_STATE_ONLY | \ - DL_FLAG_INFERRED) + DL_FLAG_INFERRED | \ + DL_FLAG_CYCLE) #define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \ DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE) @@ -752,8 +757,6 @@ struct device_link *device_link_add(struct device *consumer, if (!consumer || !supplier || consumer == supplier || flags & ~DL_ADD_VALID_FLAGS || (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) || - (flags & DL_FLAG_SYNC_STATE_ONLY && - (flags & ~DL_FLAG_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) || (flags & DL_FLAG_AUTOPROBE_CONSUMER && flags & (DL_FLAG_AUTOREMOVE_CONSUMER | DL_FLAG_AUTOREMOVE_SUPPLIER))) @@ -769,6 +772,10 @@ struct device_link *device_link_add(struct device *consumer, if (!(flags & DL_FLAG_STATELESS)) flags |= DL_FLAG_MANAGED; + if (flags & DL_FLAG_SYNC_STATE_ONLY && + !device_link_flag_is_sync_state_only(flags)) + return NULL; + device_links_write_lock(); device_pm_lock(); @@ -1728,7 +1735,7 @@ static void fw_devlink_relax_link(struct device_link *link) if (!(link->flags & DL_FLAG_INFERRED)) return; - if (link->flags == (DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE)) + if (device_link_flag_is_sync_state_only(link->flags)) return; pm_runtime_drop_link(link); @@ -1852,8 +1859,8 @@ static int fw_devlink_relax_cycle(struct device *con, void *sup) return ret; list_for_each_entry(link, &con->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (!(link->flags & DL_FLAG_CYCLE) && + device_link_flag_is_sync_state_only(link->flags)) continue; if (!fw_devlink_relax_cycle(link->consumer, sup)) @@ -1862,6 +1869,7 @@ static int fw_devlink_relax_cycle(struct device *con, void *sup) ret = 1; fw_devlink_relax_link(link); + link->flags |= DL_FLAG_CYCLE; } return ret; } diff --git a/include/linux/device.h b/include/linux/device.h index 424b55df0272..7cf24330d681 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -327,6 +327,7 @@ enum device_link_state { #define DL_FLAG_MANAGED BIT(6) #define DL_FLAG_SYNC_STATE_ONLY BIT(7) #define DL_FLAG_INFERRED BIT(8) +#define DL_FLAG_CYCLE BIT(9) /** * enum dl_dev_state - Device driver presence tracking information.