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=-17.2 required=3.0 tests=BAYES_00,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_AGENT_SANE_2 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 B8A9AC2B9F8 for ; Tue, 25 May 2021 12:12:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96A9A6140F for ; Tue, 25 May 2021 12:12:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232064AbhEYMNd (ORCPT ); Tue, 25 May 2021 08:13:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:38174 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231865AbhEYMNc (ORCPT ); Tue, 25 May 2021 08:13:32 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1621944722; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fq8F1pgJiBewPLhELJVzkzm+0rjTD8XWLO+uqVRQYwY=; b=gSF4C9wQN4z9e3iaKrrKYbCtXp3h7Y4ewwNohud4iCqtVIQLpaFBF4KGmhYoGtMX4/n06J Pcr15OJQX9egVw4EELNN5NH4clLOPX8I/o1+VncilD/wXgWULq9t2AFWX+erUZlJ2bwog1 vfGodqmeXjqf12B2GLHTZvllFkpyHR4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1621944722; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fq8F1pgJiBewPLhELJVzkzm+0rjTD8XWLO+uqVRQYwY=; b=4orZDAp+PCOxSUq1db9s0hKFS3U0rGNFcCalAhCRcqctNvbquljvmdJzFWLWHHXaj5Rb8q OgE6kJuuMXgaF3CQ== Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 19CD1AEA3; Tue, 25 May 2021 12:12:02 +0000 (UTC) Date: Tue, 25 May 2021 14:12:01 +0200 From: Jean Delvare To: Heiner Kallweit Cc: Daniel Kurtz , linux-i2c@vger.kernel.org Subject: Re: [PATCH 2/2] i2c: i801: Replace waitqueue with completion API Message-ID: <20210525141201.1fa59f3b@endymion> In-Reply-To: <1d1054de-8b47-a6bb-a264-8456705e5875@gmail.com> References: <561b74ab-b020-b0c7-c1ad-b7c3326245e3@gmail.com> <1d1054de-8b47-a6bb-a264-8456705e5875@gmail.com> Organization: SUSE Linux X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org 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. 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 ;-) > 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 -- Jean Delvare SUSE L3 Support