From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754610Ab2LDO0l (ORCPT ); Tue, 4 Dec 2012 09:26:41 -0500 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:51981 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753000Ab2LDO0k (ORCPT ); Tue, 4 Dec 2012 09:26:40 -0500 Date: Tue, 4 Dec 2012 14:31:51 +0000 From: Alan Cox To: Tomas Winkler Cc: gregkh@linuxfoundation.org, arnd@arndb.de, alan@linux.intel.com, linux-kernel@vger.kernel.org Subject: Re: [char-misc-next 07/15] mei: use wrietl/readl instead of io wrappers Message-ID: <20121204143151.1cce530a@pyramind.ukuu.org.uk> In-Reply-To: <1354629884-3202-7-git-send-email-tomas.winkler@intel.com> References: <1354629884-3202-1-git-send-email-tomas.winkler@intel.com> <1354629884-3202-7-git-send-email-tomas.winkler@intel.com> X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Dec 2012 16:04:36 +0200 Tomas Winkler wrote: > on intel registers are alwasy memory mapped so drop > the overhead of iowrite32 and ioread32 > > Signed-off-by: Tomas Winkler > --- > drivers/misc/mei/mei_dev.h | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h > index 92a5d9a..37eb041 100644 > --- a/drivers/misc/mei/mei_dev.h > +++ b/drivers/misc/mei/mei_dev.h > @@ -438,7 +438,7 @@ int mei_amthif_irq_read(struct mei_device *dev, s32 *slots); > static inline u32 mei_reg_read(const struct mei_device *dev, > unsigned long offset) > { > - return ioread32(dev->mem_addr + offset); > + return readl(dev->mem_addr + offset); > } > > /** > @@ -451,7 +451,7 @@ static inline u32 mei_reg_read(const struct mei_device *dev, > static inline void mei_reg_write(const struct mei_device *dev, > unsigned long offset, u32 value) > { > - iowrite32(value, dev->mem_addr + offset); > + writel(value, dev->mem_addr + offset); ioremap should match readl/writel iomap iowrite32/ioread32 so you need to tweak the map/unmap if you do this. As to overhead. I'd love to see a measurement that can detect the difference. Do you have a benchmark that shows it ?