From patchwork Sun Jun 15 00:41:35 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lv Zheng X-Patchwork-Id: 4353791 Return-Path: X-Original-To: patchwork-linux-acpi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 192E59F466 for ; Sun, 15 Jun 2014 00:41:57 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0B59120279 for ; Sun, 15 Jun 2014 00:41:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 197742027D for ; Sun, 15 Jun 2014 00:41:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751143AbaFOAls (ORCPT ); Sat, 14 Jun 2014 20:41:48 -0400 Received: from mail-pa0-f52.google.com ([209.85.220.52]:62921 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750917AbaFOAlr (ORCPT ); Sat, 14 Jun 2014 20:41:47 -0400 Received: by mail-pa0-f52.google.com with SMTP id eu11so3299029pac.39 for ; Sat, 14 Jun 2014 17:41:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=ZglbBlBnpq2p3K1TEB7qs8eaXfDwTIjLnOtWfSdCWYM=; b=Od04kp50/NA2r7E10O6u6vkLPADlRmCH1mSoq5DnCdC+RvNxmYUQrFnBr80X8a/hxc 7aJp60qZIYCKjtx27WQ9QQUExWpCixgTpGkc88+vJThzuA/e0nsZ5Hrs/O17k5KJmadW XpB0oBWzEGIrP2xnBwwUZnfIGfLotd7rDJVdXvOL0QP06fO6IlyJvNn1RxIP1+4BAcyp hVv9EWsV4jItf+HhEdh1bspA+wSVdKfTb+uHJjBRS1o/CxGda2Wb3xTKKHhg0qpm+gFl PBSWloMP3ftAIvjKWd6R5kEHLBv5tByux8yuVZds88ve1prSep23aSkpsLB7wxa/5B+o OU3w== X-Received: by 10.69.26.103 with SMTP id ix7mr13523949pbd.41.1402792906823; Sat, 14 Jun 2014 17:41:46 -0700 (PDT) Received: from localhost.localdomain ([180.169.136.70]) by mx.google.com with ESMTPSA id pr4sm10869259pbb.53.2014.06.14.17.41.43 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 14 Jun 2014 17:41:46 -0700 (PDT) From: Lv Zheng To: "Rafael J. Wysocki" , Len Brown Cc: Lv Zheng , Lv Zheng , , linux-acpi@vger.kernel.org Subject: [PATCH v2 2/7] ACPI/EC: Add asynchronous command byte write support. Date: Sun, 15 Jun 2014 08:41:35 +0800 Message-Id: <027a446795ce6a1cd3fd289a5ca04c7e26506b13.1402792240.git.lv.zheng@intel.com> X-Mailer: git-send-email 1.7.10 In-Reply-To: References: Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Spam-Status: No, score=-7.4 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Lv Zheng This patch moves the first command byte write into advance_transaction() so that all EC register accesses that can affect the command processing state machine can happen in this asynchronous state machine advancement function. The advance_transaction() function then can be a complete implementation of an asyncrhonous transaction for a single command so that: 1. The first command byte can be written in the interrupt context; 2. The command completion waiter can also be used to wait the first command byte's timeout; 3. In BURST mode, the follow-up command bytes can be written in the interrupt context directly, so that it doesn't need to return to the task context. Returning to the task context reduces the throughput of the BURST mode and in the worst cases where the system workload is very high, this leads to the hardware driven automatic BURST mode exit. In order not to increase memory consumptions, this patch converts 'done' into 'flags' to contain multiple indications: 1. ACPI_EC_COMMAND_COMPLETE: converting from original 'done' condition, indicating the completion of the command transaction. 2. ACPI_EC_COMMAND_POLL: indicating the availability of writing the first command byte. A new command can utilize this flag to compete for the right of accessing the underlying hardware. There is a follow-up bug fix that has utilized this new flag. The 2 flags are important because it also reflects a key concept of IO programs' design used in the system softwares. Normally an IO program running in the kernel should first be implemented in the asynchronous way. And the 2 flags are the most common way to implement its synchronous operations on top of the asynchronous operations: 1. POLL: This flag can be used to block until the asynchronous operations can happen. 2. COMPLETE: This flag can be used to block until the asynchronous operations have completed. By constructing code cleanly in this way, many difficult problems can be solved smoothly. [zetalog: changelog updated] Reference: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Signed-off-by: Lv Zheng Reported-and-tested-by: Gareth Williams Tested-by: Steffen Weber [zetalog: first affected by:] Cc: # 2.6.11: 7c6db4e0: ACPI: EC: do transaction from interrupt context [zetalog: cleanly applying to:] Cc: # 3.14.x: 42b946bb: ACPI / EC: disable GPE before removing GPE handler --- drivers/acpi/ec.c | 83 +++++++++++++++++++++++++++++++---------------------- 1 file changed, 48 insertions(+), 35 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 762b4cc..f09386e 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -78,6 +78,9 @@ enum { EC_FLAGS_BLOCKED, /* Transactions are blocked */ }; +#define ACPI_EC_COMMAND_POLL 0x01 /* Available for command byte */ +#define ACPI_EC_COMMAND_COMPLETE 0x02 /* Completed last byte */ + /* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */ static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY; module_param(ec_delay, uint, 0644); @@ -109,7 +112,7 @@ struct transaction { u8 ri; u8 wlen; u8 rlen; - bool done; + u8 flags; }; struct acpi_ec *boot_ec, *first_ec; @@ -150,63 +153,68 @@ static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data) outb(data, ec->data_addr); } -static int ec_transaction_done(struct acpi_ec *ec) +static int ec_transaction_completed(struct acpi_ec *ec) { unsigned long flags; int ret = 0; spin_lock_irqsave(&ec->lock, flags); - if (!ec->curr || ec->curr->done) + if (!ec->curr || (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE)) ret = 1; spin_unlock_irqrestore(&ec->lock, flags); return ret; } -static void start_transaction(struct acpi_ec *ec) -{ - ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0; - ec->curr->done = false; - acpi_ec_write_cmd(ec, ec->curr->command); -} - static void advance_transaction(struct acpi_ec *ec) { - unsigned long flags; struct transaction *t; u8 status; - spin_lock_irqsave(&ec->lock, flags); pr_debug("===== %s =====\n", in_interrupt() ? "IRQ" : "TASK"); status = acpi_ec_read_status(ec); t = ec->curr; if (!t) - goto unlock; - if (t->wlen > t->wi) { - if ((status & ACPI_EC_FLAG_IBF) == 0) - acpi_ec_write_data(ec, - t->wdata[t->wi++]); - else - goto err; - } else if (t->rlen > t->ri) { - if ((status & ACPI_EC_FLAG_OBF) == 1) { - t->rdata[t->ri++] = acpi_ec_read_data(ec); - if (t->rlen == t->ri) - t->done = true; + goto err; + if (t->flags & ACPI_EC_COMMAND_POLL) { + if (t->wlen > t->wi) { + if ((status & ACPI_EC_FLAG_IBF) == 0) + acpi_ec_write_data(ec, t->wdata[t->wi++]); + else + goto err; + } else if (t->rlen > t->ri) { + if ((status & ACPI_EC_FLAG_OBF) == 1) { + t->rdata[t->ri++] = acpi_ec_read_data(ec); + if (t->rlen == t->ri) + t->flags |= ACPI_EC_COMMAND_COMPLETE; + } else + goto err; + } else if (t->wlen == t->wi && + (status & ACPI_EC_FLAG_IBF) == 0) + t->flags |= ACPI_EC_COMMAND_COMPLETE; + return; + } else { + if ((status & ACPI_EC_FLAG_IBF) == 0) { + acpi_ec_write_cmd(ec, t->command); + t->flags |= ACPI_EC_COMMAND_POLL; } else goto err; - } else if (t->wlen == t->wi && - (status & ACPI_EC_FLAG_IBF) == 0) - t->done = true; - goto unlock; + return; + } err: /* * If SCI bit is set, then don't think it's a false IRQ * otherwise will take a not handled IRQ as a false one. */ - if (in_interrupt() && !(status & ACPI_EC_FLAG_SCI)) - ++t->irq_count; + if (!(status & ACPI_EC_FLAG_SCI)) { + if (in_interrupt() && t) + ++t->irq_count; + } +} -unlock: - spin_unlock_irqrestore(&ec->lock, flags); +static void start_transaction(struct acpi_ec *ec) +{ + ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0; + ec->curr->flags = 0; + advance_transaction(ec); } static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data); @@ -231,15 +239,17 @@ static int ec_poll(struct acpi_ec *ec) /* don't sleep with disabled interrupts */ if (EC_FLAGS_MSI || irqs_disabled()) { udelay(ACPI_EC_MSI_UDELAY); - if (ec_transaction_done(ec)) + if (ec_transaction_completed(ec)) return 0; } else { if (wait_event_timeout(ec->wait, - ec_transaction_done(ec), + ec_transaction_completed(ec), msecs_to_jiffies(1))) return 0; } + spin_lock_irqsave(&ec->lock, flags); advance_transaction(ec); + spin_unlock_irqrestore(&ec->lock, flags); } while (time_before(jiffies, delay)); pr_debug("controller reset, restart transaction\n"); spin_lock_irqsave(&ec->lock, flags); @@ -637,10 +647,13 @@ static int ec_check_sci(struct acpi_ec *ec, u8 state) static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, u32 gpe_number, void *data) { + unsigned long flags; struct acpi_ec *ec = data; + spin_lock_irqsave(&ec->lock, flags); advance_transaction(ec); - if (ec_transaction_done(ec) && + spin_unlock_irqrestore(&ec->lock, flags); + if (ec_transaction_completed(ec) && (acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF) == 0) { wake_up(&ec->wait); ec_check_sci(ec, acpi_ec_read_status(ec));