From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751309AbcBLIie (ORCPT ); Fri, 12 Feb 2016 03:38:34 -0500 Received: from eusmtp01.atmel.com ([212.144.249.242]:52073 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750967AbcBLIic (ORCPT ); Fri, 12 Feb 2016 03:38:32 -0500 Date: Fri, 12 Feb 2016 09:38:28 +0100 From: Ludovic Desroches To: Ulf Hansson CC: Ludovic Desroches , linux-mmc , "linux-kernel@vger.kernel.org" , Nicolas Ferre , Adrian Hunter Subject: Re: [PATCH] mmc: sdhci-of-at91: fix card detect when using runtime PM Message-ID: <20160212083828.GI14937@odux.rfo.atmel.com> Mail-Followup-To: Ulf Hansson , linux-mmc , "linux-kernel@vger.kernel.org" , Nicolas Ferre , Adrian Hunter References: <1455198537-21791-1-git-send-email-ludovic.desroches@atmel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 11, 2016 at 04:10:54PM +0100, Ulf Hansson wrote: > 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? Sorry but I am not sure to understand. In the previous thread, you told me to use MMC_CAP_NEEDS_POLL which is set if we have SDHCI_QUIRK_BROKEN_CARD_DETECTION. I was not confortable to do this because as you say it is not reflecting the capability of the hardware. Do you mean that I can simply add MMC_CAP_NEEDS_POLL after sdhci_add_host()? Regards Ludovic > > 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