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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02B2AEB64DC for ; Mon, 26 Jun 2023 17:59:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231167AbjFZR76 (ORCPT ); Mon, 26 Jun 2023 13:59:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231267AbjFZR7z (ORCPT ); Mon, 26 Jun 2023 13:59:55 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FD71183 for ; Mon, 26 Jun 2023 10:59:54 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 1574F1F8AC; Mon, 26 Jun 2023 17:59:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1687802393; 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=R7jXnQJJLbMOsuBV4nfWimuSYR7MWc+iGxoZPRd7UZk=; b=QiRF3UF5RBX6NUf9IoVnhOzCAkD3SL1BcXR1jQvFDvsf88rJ2peZr4qSwYvoNeoB9212zp xCXUBYFTn/z+kgXqaURt+kv71ULbRz2QYzU4sdmVJsY/fVARQDZGSJ5nG1K915dGpNCCRE GLHxTkHW3SEliVL+DYkhWLs4juba6/w= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1687802393; 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=R7jXnQJJLbMOsuBV4nfWimuSYR7MWc+iGxoZPRd7UZk=; b=NPwzdI/jYlEXhwGzJ1OQd3+1oi0FjoRObXTn7HpDSmfwMrSitBPyLhzfsaNixNxv5emr0M ZKSMOx2kNyvy2QDQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id E9B8A13483; Mon, 26 Jun 2023 17:59:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Muz1NhjSmWRzaAAAMHmgww (envelope-from ); Mon, 26 Jun 2023 17:59:52 +0000 Date: Mon, 26 Jun 2023 19:59:51 +0200 From: Jean Delvare To: Heiner Kallweit Cc: linux-i2c@vger.kernel.org Subject: Re: [PATCH 2/4] i2c: i801: Replace acpi_lock with I2C bus lock Message-ID: <20230626195951.1695cda6@endymion.delvare> In-Reply-To: <8f88906f-c7da-eb3a-2f14-0f4d46202517@gmail.com> References: <8f88906f-c7da-eb3a-2f14-0f4d46202517@gmail.com> Organization: SUSE Linux X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.34; 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, On Sat, 04 Mar 2023 22:33:05 +0100, Heiner Kallweit wrote: > I2C core ensures in i2c_smbus_xfer() that the I2C bus lock is held when > calling the smbus_xfer callback. That's i801_access() in our case. > I think it's safe in general to assume that the I2C bus lock is held > when the smbus_xfer callback is called. > Therefore I see no need to define an own mutex. > > Signed-off-by: Heiner Kallweit > --- > drivers/i2c/busses/i2c-i801.c | 14 ++++---------- > 1 file changed, 4 insertions(+), 10 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > index d6a0c3b53..7641bd0ac 100644 > --- a/drivers/i2c/busses/i2c-i801.c > +++ b/drivers/i2c/busses/i2c-i801.c > @@ -289,10 +289,9 @@ struct i801_priv { > > /* > * If set to true the host controller registers are reserved for > - * ACPI AML use. Protected by acpi_lock. > + * ACPI AML use. > */ > bool acpi_reserved; > - struct mutex acpi_lock; > }; > > #define FEATURE_SMBUS_PEC BIT(0) > @@ -871,11 +870,8 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > int hwpec, ret; > struct i801_priv *priv = i2c_get_adapdata(adap); > > - mutex_lock(&priv->acpi_lock); > - if (priv->acpi_reserved) { > - mutex_unlock(&priv->acpi_lock); > + if (priv->acpi_reserved) > return -EBUSY; > - } > > pm_runtime_get_sync(&priv->pci_dev->dev); > > @@ -916,7 +912,6 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > > pm_runtime_mark_last_busy(&priv->pci_dev->dev); > pm_runtime_put_autosuspend(&priv->pci_dev->dev); > - mutex_unlock(&priv->acpi_lock); > return ret; > } > > @@ -1566,7 +1561,7 @@ i801_acpi_io_handler(u32 function, acpi_physical_address address, u32 bits, > * further access from the driver itself. This device is now owned > * by the system firmware. > */ > - mutex_lock(&priv->acpi_lock); > + i2c_lock_bus(&priv->adapter, I2C_LOCK_SEGMENT); > > if (!priv->acpi_reserved && i801_acpi_is_smbus_ioport(priv, address)) { > priv->acpi_reserved = true; > @@ -1586,7 +1581,7 @@ i801_acpi_io_handler(u32 function, acpi_physical_address address, u32 bits, > else > status = acpi_os_write_port(address, (u32)*value, bits); > > - mutex_unlock(&priv->acpi_lock); > + i2c_unlock_bus(&priv->adapter, I2C_LOCK_SEGMENT); > > return status; > } > @@ -1640,7 +1635,6 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id) > priv->adapter.dev.parent = &dev->dev; > ACPI_COMPANION_SET(&priv->adapter.dev, ACPI_COMPANION(&dev->dev)); > priv->adapter.retries = 3; > - mutex_init(&priv->acpi_lock); > > priv->pci_dev = dev; > priv->features = id->driver_data; Looks reasonable, I also can't see any reason why that wouldn't work. But locking and power management can be tricky of course. I'll test this for some time, but I don't think my system actually suffers from this ACPI resource conflict, so this most probably won't be testing much in practice. Thanks, -- Jean Delvare SUSE L3 Support