Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755425Ab1EDTsO (ORCPT ); Wed, 4 May 2011 15:48:14 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:55705 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751764Ab1EDTsN convert rfc822-to-8bit (ORCPT ); Wed, 4 May 2011 15:48:13 -0400 MIME-Version: 1.0 In-Reply-To: References: <1304525161-14448-1-git-send-email-per.forlin@linaro.org> <1304525161-14448-2-git-send-email-per.forlin@linaro.org> Date: Wed, 4 May 2011 21:48:12 +0200 Message-ID: Subject: Re: [PATCH v2] sdio: optimized SDIO IRQ handling for single irq From: Per Forlin To: Nicolas Pitre Cc: linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linaro-dev@lists.linaro.org, Stefan Nilsson XK Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2831 Lines: 80 On 4 May 2011 19:34, Nicolas Pitre wrote: > On Wed, 4 May 2011, Per Forlin wrote: > >> From: Stefan Nilsson XK >> >> If there is only 1 function registered it is possible to >> improve performance by directly calling the irq handler >> and avoiding the overhead of reading the CCCR registers. >> >> Signed-off-by: Per Forlin >> Acked-by: Ulf Hansson >> --- >> ?drivers/mmc/core/sdio_irq.c | ? 30 ++++++++++++++++++++++++++++++ >> ?include/linux/mmc/card.h ? ?| ? ?1 + >> ?2 files changed, 31 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c >> index b300161..64c4409 100644 >> --- a/drivers/mmc/core/sdio_irq.c >> +++ b/drivers/mmc/core/sdio_irq.c >> @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) >> ? ? ? int i, ret, count; >> ? ? ? unsigned char pending; >> >> + ? ? /* >> + ? ? ?* Optimization, if there is only 1 function registered >> + ? ? ?* call irq handler directly >> + ? ? ?*/ >> + ? ? if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { >> + ? ? ? ? ? ? struct sdio_func *func = card->sdio_single_irq; >> + ? ? ? ? ? ? func->irq_handler(func); > > I think there is little point using a func variable here, especially > since you already reference the handler pointer in the if() statement. > Hence: > > ? ? ? ?if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { > ? ? ? ? ? ? ? ?card->sdio_single_irq->irq_handler(); > ? ? ? ? ? ? ? ?return 1; > ? ? ? ?} > What do you think about: + struct sdio_func *func = card->sdio_single_irq; + + /* + * Optimization, if there is only 1 function interrupt registered + * call irq handler directly + */ + if (func) { + func->irq_handler(func); + return 1; + } - struct sdio_func *func = card->sdio_func[i - 1]; + func = card->sdio_func[i - 1]; >> @@ -186,6 +196,24 @@ static int sdio_card_irq_put(struct mmc_card *card) >> ? ? ? return 0; >> ?} >> >> +/* If there is only 1 function registered set sdio_single_irq */ >> +static void sdio_single_irq_set(struct mmc_card *card) >> +{ > > The comment is slightly wrong. ?This should say "only 1 function > interrupt registered..." ?Nothing prevents this from working with > multiple functions if only one of them has claimed an interrupt. > > Other than that: > > Reviewed-by: Nicolas Pitre > > > Nicolas > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/