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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 0A348C41538 for ; Mon, 10 May 2021 12:16:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F147D613C8 for ; Mon, 10 May 2021 12:16:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245477AbhEJMNE (ORCPT ); Mon, 10 May 2021 08:13:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:41148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236552AbhEJLIR (ORCPT ); Mon, 10 May 2021 07:08:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C52A86199F; Mon, 10 May 2021 11:02:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620644526; bh=TgVC4UPVRHZNBIu5csNjWVaW5ddsvCz1lELdgxWi99I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nwE4ycgck8y5T80Aazgf5pYKsD7fQxRe2OBpA8XspB/oQHK+g0B5pYaF9hElueSQJ GVL63pGMtyHSsMQOrKaTtD3zJe9T5HWtLVFnL1AG2xF7HEUadXTs78/dpfhvdLU5IW C2cejvt6kXiEBRC4BhrdrrorsDANoUbRBQ6gApBA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Srinivas Pandruvada , Hans de Goede , Sasha Levin Subject: [PATCH 5.12 111/384] platform/x86: ISST: Account for increased timeout in some cases Date: Mon, 10 May 2021 12:18:20 +0200 Message-Id: <20210510102018.561089412@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210510102014.849075526@linuxfoundation.org> References: <20210510102014.849075526@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Srinivas Pandruvada [ Upstream commit 5c782817a981981917ec3c647cf521022ee07143 ] In some cases when firmware is busy or updating, some mailbox commands still timeout on some newer CPUs. To fix this issue, change how we process timeout. With this change, replaced timeout from using simple count with real timeout in micro-seconds using ktime. When the command response takes more than average processing time, yield to other tasks. The worst case timeout is extended upto 1 milli-second. Signed-off-by: Srinivas Pandruvada Link: https://lore.kernel.org/r/20210330220840.3113959-1-srinivas.pandruvada@linux.intel.com Signed-off-by: Hans de Goede Signed-off-by: Sasha Levin --- .../intel_speed_select_if/isst_if_mbox_pci.c | 33 +++++++++++++------ 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c index a2a2d923e60c..df1fc6c719f3 100644 --- a/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c @@ -21,12 +21,16 @@ #define PUNIT_MAILBOX_BUSY_BIT 31 /* - * The average time to complete some commands is about 40us. The current - * count is enough to satisfy 40us. But when the firmware is very busy, this - * causes timeout occasionally. So increase to deal with some worst case - * scenarios. Most of the command still complete in few us. + * The average time to complete mailbox commands is less than 40us. Most of + * the commands complete in few micro seconds. But the same firmware handles + * requests from all power management features. + * We can create a scenario where we flood the firmware with requests then + * the mailbox response can be delayed for 100s of micro seconds. So define + * two timeouts. One for average case and one for long. + * If the firmware is taking more than average, just call cond_resched(). */ -#define OS_MAILBOX_RETRY_COUNT 100 +#define OS_MAILBOX_TIMEOUT_AVG_US 40 +#define OS_MAILBOX_TIMEOUT_MAX_US 1000 struct isst_if_device { struct mutex mutex; @@ -35,11 +39,13 @@ struct isst_if_device { static int isst_if_mbox_cmd(struct pci_dev *pdev, struct isst_if_mbox_cmd *mbox_cmd) { - u32 retries, data; + s64 tm_delta = 0; + ktime_t tm; + u32 data; int ret; /* Poll for rb bit == 0 */ - retries = OS_MAILBOX_RETRY_COUNT; + tm = ktime_get(); do { ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE, &data); @@ -48,11 +54,14 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) { ret = -EBUSY; + tm_delta = ktime_us_delta(ktime_get(), tm); + if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US) + cond_resched(); continue; } ret = 0; break; - } while (--retries); + } while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US); if (ret) return ret; @@ -74,7 +83,8 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, return ret; /* Poll for rb bit == 0 */ - retries = OS_MAILBOX_RETRY_COUNT; + tm_delta = 0; + tm = ktime_get(); do { ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE, &data); @@ -83,6 +93,9 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) { ret = -EBUSY; + tm_delta = ktime_us_delta(ktime_get(), tm); + if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US) + cond_resched(); continue; } @@ -96,7 +109,7 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, mbox_cmd->resp_data = data; ret = 0; break; - } while (--retries); + } while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US); return ret; } -- 2.30.2