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=-23.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham 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 0B868C47089 for ; Thu, 27 May 2021 07:13:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E300F613BC for ; Thu, 27 May 2021 07:13:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234882AbhE0HPE (ORCPT ); Thu, 27 May 2021 03:15:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234709AbhE0HPD (ORCPT ); Thu, 27 May 2021 03:15:03 -0400 Received: from mail-ej1-x630.google.com (mail-ej1-x630.google.com [IPv6:2a00:1450:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43540C061574 for ; Thu, 27 May 2021 00:13:28 -0700 (PDT) Received: by mail-ej1-x630.google.com with SMTP id lg14so6370986ejb.9 for ; Thu, 27 May 2021 00:13:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=F7d6rD7/V6Y9LKWJDti8OGp2OsRqZR18e/m5mE83otg=; b=evcyVQtJRlTtU2OHcLDuJO3XkgHCRm8HbTsK7GLVkUeDfQrLL/T6+pC/QukA5b+aab SDRyUHJKs+9RYxnHecVJrrGB2pSUAXTOptdBcXOagHRTo9m62JmDpT3URmIUeSPiVPP9 PoWzq4t+A02ff3jhiuHN3KzlthTjmhRh3aaRO/Bv1c4VyUNayHijXES7940ub3sy8bOK dAElUZWLaWaheI5ScVM0NhGmdBjbJIWvBnmFr8fX88pzIoEleHlYJL2FCdwsn0d1Ulh+ n5NTMBCXlOnc3IHOJhfzA4QuNikBhjZPV++Lga0+PvwLfvVpTMRw20nUdn+Ng8kQOOUA 7z1w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=F7d6rD7/V6Y9LKWJDti8OGp2OsRqZR18e/m5mE83otg=; b=F74Ch/A9GfFu+Du9YkLhYABpq6Y47LQdPgWNQ9dGFGfrnaLnhVC3+9Iwex2EXWU3qF ARnbqLTc88cZd/G6L+KfxA0k9xRdvVA2rmSPkTGn8VS0t5e+KBtVMLBWeg78dpa1r62Q 4qi0IvynXI71KBcPg5x8S0Fg7UrdyC89w+C1hUgiUrnxBmJOucbMjSNhioXBkQ3aOUUb i/7lCcZeSTuWU9/VRIQrxxI9a9uSIAuehaAxQnP1TFFo6V/+pnPByi+xpOOiEQs5SpRy U2KS/52ReOY+O/FYypG3MnKQewXGI8gx96QBZ+1Q740MjKXTfd7iS5QxTEqcVKF6d/HA xx0Q== X-Gm-Message-State: AOAM530AhrlIrhHOMJG48ofIepEdyTlE3sFNk5WGQv7yquFPernkegzl sTiq5DPl/rLe8uXNUfbfGY5ecJth1srC8qUMOghqBw== X-Google-Smtp-Source: ABdhPJy7wPBRQeZslYDOCIi35J5XtaEXrSGiNzUO8ZoEiNkKMVOlkHyS+Y+nzPT9SU4eXFr4/qYLh/7Mbw4RbwW2DWM= X-Received: by 2002:a17:907:990f:: with SMTP id ka15mr2351253ejc.132.1622099606616; Thu, 27 May 2021 00:13:26 -0700 (PDT) MIME-Version: 1.0 References: <561b74ab-b020-b0c7-c1ad-b7c3326245e3@gmail.com> <1d1054de-8b47-a6bb-a264-8456705e5875@gmail.com> <20210525141201.1fa59f3b@endymion> In-Reply-To: From: Daniel Kurtz Date: Thu, 27 May 2021 17:13:14 +1000 Message-ID: Subject: Re: [PATCH 2/2] i2c: i801: Replace waitqueue with completion API To: Heiner Kallweit Cc: Jean Delvare , Linux I2C Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Hi Jean, Heiner, On Tue, May 25, 2021 at 11:01 PM Heiner Kallweit wrote: > > On 25.05.2021 14:12, Jean Delvare wrote: > > Hi Heiner, > > > > Adding Daniel Kurtz, who wrote the original wait queue-based code, to > > Cc. I'm not sure if Daniel is still into kernel code though. Thanks for thinking of me! I'm still into kernel code, but I do a lot more reading than writing these days. > > > > On Sat, 22 May 2021 00:02:43 +0200, Heiner Kallweit wrote: > >> Using the completion API is more intuitive and it allows to simplify > >> the code. Note that we don't have to set priv->status = 0 any longer > >> with the completion API. > > > > OK, but you need to call reinit_completion() instead, which has the > > same cost. So that's not a good argument ;-) > > > Maybe my comment wasn't clear enough. I didn't want to say that we > save something but that it's safe from a functional point of view > to remove clearing priv->status. > > >> Signed-off-by: Heiner Kallweit > >> --- > >> drivers/i2c/busses/i2c-i801.c | 48 ++++++++++++++--------------------- > >> 1 file changed, 19 insertions(+), 29 deletions(-) > >> > >> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > >> index bfea94d02..738204d77 100644 > >> --- a/drivers/i2c/busses/i2c-i801.c > >> +++ b/drivers/i2c/busses/i2c-i801.c > >> @@ -103,7 +103,7 @@ > >> #include > >> #include > >> #include > >> -#include > >> +#include > >> #include > >> #include > >> #include > >> @@ -270,7 +270,7 @@ struct i801_priv { > >> unsigned int features; > >> > >> /* isr processing */ > >> - wait_queue_head_t waitq; > >> + struct completion done; > >> u8 status; > >> > >> /* Command state used by isr for byte-by-byte block transactions */ > >> @@ -496,24 +496,19 @@ static int i801_wait_byte_done(struct i801_priv *priv) > >> static int i801_transaction(struct i801_priv *priv, int xact) > >> { > >> int status; > >> - int result; > >> + unsigned long result; > >> const struct i2c_adapter *adap = &priv->adapter; > >> > >> - result = i801_check_pre(priv); > >> - if (result < 0) > >> - return result; > >> + status = i801_check_pre(priv); > >> + if (status < 0) > >> + return status; > >> > >> if (priv->features & FEATURE_IRQ) { > >> + reinit_completion(&priv->done); > >> outb_p(xact | SMBHSTCNT_INTREN | SMBHSTCNT_START, > >> SMBHSTCNT(priv)); > >> - result = wait_event_timeout(priv->waitq, > >> - (status = priv->status), > >> - adap->timeout); > >> - if (!result) > >> - status = -ETIMEDOUT; > >> - > >> - priv->status = 0; > >> - return i801_check_post(priv, status); > >> + result = wait_for_completion_timeout(&priv->done, adap->timeout); > >> + return i801_check_post(priv, result ? priv->status : -ETIMEDOUT); > >> } > >> > >> /* the current contents of SMBHSTCNT can be overwritten, since PEC, > >> @@ -638,7 +633,7 @@ static irqreturn_t i801_host_notify_isr(struct i801_priv *priv) > >> * DEV_ERR - Invalid command, NAK or communication timeout > >> * BUS_ERR - SMI# transaction collision > >> * FAILED - transaction was canceled due to a KILL request > >> - * When any of these occur, update ->status and wake up the waitq. > >> + * When any of these occur, update ->status and signal completion. > >> * ->status must be cleared before kicking off the next transaction. > >> * > >> * 2) For byte-by-byte (I2C read/write) transactions, one BYTE_DONE interrupt > >> @@ -675,7 +670,7 @@ static irqreturn_t i801_isr(int irq, void *dev_id) > >> if (status) { > >> outb_p(status, SMBHSTSTS(priv)); > >> priv->status = status; > >> - wake_up(&priv->waitq); > >> + complete(&priv->done); > >> } > >> > >> return IRQ_HANDLED; > >> @@ -694,15 +689,15 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, > >> int i, len; > >> int smbcmd; > >> int status; > >> - int result; > >> + unsigned long result; > >> const struct i2c_adapter *adap = &priv->adapter; > >> > >> if (command == I2C_SMBUS_BLOCK_PROC_CALL) > >> return -EOPNOTSUPP; > >> > >> - result = i801_check_pre(priv); > >> - if (result < 0) > >> - return result; > >> + status = i801_check_pre(priv); > >> + if (status < 0) > >> + return status; > >> > >> len = data->block[0]; > >> > >> @@ -726,15 +721,10 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv, > >> priv->count = 0; > >> priv->data = &data->block[1]; > >> > >> + reinit_completion(&priv->done); > >> outb_p(priv->cmd | SMBHSTCNT_START, SMBHSTCNT(priv)); > >> - result = wait_event_timeout(priv->waitq, > >> - (status = priv->status), > >> - adap->timeout); > >> - if (!result) > >> - status = -ETIMEDOUT; > >> - > >> - priv->status = 0; > >> - return i801_check_post(priv, status); > >> + result = wait_for_completion_timeout(&priv->done, adap->timeout); > >> + return i801_check_post(priv, result ? priv->status : -ETIMEDOUT); > >> } > >> > >> for (i = 1; i <= len; i++) { > >> @@ -1889,7 +1879,7 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id) > >> } > >> > >> if (priv->features & FEATURE_IRQ) { > >> - init_waitqueue_head(&priv->waitq); > >> + init_completion(&priv->done); > >> > >> err = devm_request_irq(&dev->dev, dev->irq, i801_isr, > >> IRQF_SHARED, > > > > The clean-up isn't massive but I agree the code is a bit more pleasant > > to read after the change, and I also see the binary size shrink a bit, > > so I vote for it. > > > > Reviewed-by: Jean Delvare > > Tested-by: Jean Delvare > > > I agree, shorter and sweeter. Thanks for cleaning this up! Reviewed-by: Daniel Kurtz