From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751845AbcBKPLB (ORCPT ); Thu, 11 Feb 2016 10:11:01 -0500 Received: from mail-yk0-f175.google.com ([209.85.160.175]:33790 "EHLO mail-yk0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750987AbcBKPKz (ORCPT ); Thu, 11 Feb 2016 10:10:55 -0500 MIME-Version: 1.0 In-Reply-To: <1455198537-21791-1-git-send-email-ludovic.desroches@atmel.com> References: <1455198537-21791-1-git-send-email-ludovic.desroches@atmel.com> Date: Thu, 11 Feb 2016 16:10:54 +0100 Message-ID: Subject: Re: [PATCH] mmc: sdhci-of-at91: fix card detect when using runtime PM From: Ulf Hansson To: Ludovic Desroches Cc: linux-mmc , "linux-kernel@vger.kernel.org" , Nicolas Ferre , Adrian Hunter Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11 February 2016 at 14:48, Ludovic Desroches wrote: > Add quirk broken card detection to enable card detection polling. It is > a short term solution until reworking PM stuff. > > If the card detect signal is connected to the sdhci controller and not a > gpio, when runtime PM suspend happens, we have no way to wake up on a card > detect event since these irqs are no more enabled. > > Signed-off-by: Ludovic Desroches > Fixes: f5f17813ae9b ("mmc: sdhci-of-at91: add PM support") > --- > drivers/mmc/host/sdhci-of-at91.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c > index 9cb86fb..efec736 100644 > --- a/drivers/mmc/host/sdhci-of-at91.c > +++ b/drivers/mmc/host/sdhci-of-at91.c > @@ -45,6 +45,7 @@ static const struct sdhci_ops sdhci_at91_sama5d2_ops = { > > static const struct sdhci_pltfm_data soc_data_sama5d2 = { > .ops = &sdhci_at91_sama5d2_ops, > + .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION, > .quirks2 = SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST, > }; > > -- > 2.7.0 > According to the below commit, SDHCI_QUIRK_BROKEN_CARD_DETECTION was invented because of unreliable card detection mechanism inside the sdhci controller. Therefore it required polling to be used, but also to make ->get_cd() to always return 1 in these cases. Although, as I understand it that's not the case here. You can still rely on card detection to work, but as you don't have wakeups you can't fully make use of card detect, when combined with runtime PM. I am not sure we should add more users of SDHCI_QUIRK_BROKEN_CARD_DETECTION, especially since in this case it's not reflecting the capability of the hardware. Can't we think of another way? Kind regards Uffe commit 68d1fb7e229c6f95be4fbbe3eb46b24e41184924 Author: Anton Vorontsov sdhci: Add support for card-detection polling This patch adds SDHCI_QUIRK_BROKEN_CARD_DETECTION quirk. When specified, sdhci driver will set MMC_CAP_NEEDS_POLL MMC host capability, and won't enable card insert/remove interrupts. This is needed for hosts with unreliable card detection, such as FSL eSDHC. The original eSDHC driver was tring to "debounce" card-detection IRQs by reading present state and disabling particular interrupts. But with this debouncing scheme I noticed that sometimes we miss card insertion/removal events. Signed-off-by: Anton Vorontsov Signed-off-by: Pierre Ossman