From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH v4 05/12] mmc: sdhci: Disable HS200/HS400 mode if controller can't support 1.8v Date: Thu, 26 Apr 2018 13:40:01 +0300 Message-ID: References: <20180425120937.29867-1-kishon@ti.com> <20180425120937.29867-6-kishon@ti.com> <6bdf4feb-bc12-3779-3de6-e08af1d4f518@intel.com> <7b877764-22f3-e13b-a8da-1e0b997b4b74@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <7b877764-22f3-e13b-a8da-1e0b997b4b74@ti.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Kishon Vijay Abraham I , Ulf Hansson Cc: Rob Herring , Mark Rutland , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Tony Lindgren List-Id: devicetree@vger.kernel.org On 26/04/18 13:08, Kishon Vijay Abraham I wrote: > Hi Adrian, > > On Thursday 26 April 2018 02:25 PM, Adrian Hunter wrote: >> On 25/04/18 15:09, Kishon Vijay Abraham I wrote: >>> Though MMC controller can indicate HS200/HS400 mode capability (by >>> using "mmc-hs200-1_8v"/"mmc-hs400-1_8v" dt property), if the IO lines >>> in the board is connected to 3.3v supply, HS200/HS400 mode cannot be >>> supported. Such boards have "no-1-8-v" property in their dts file. >>> Disable HS200/HS400 mode for boards which have "no-1-8-v" set. >>> >>> Signed-off-by: Kishon Vijay Abraham I >>> Acked-by: Tony Lindgren >>> --- >>> drivers/mmc/host/sdhci.c | 1 + >>> include/linux/mmc/host.h | 1 + >>> 2 files changed, 2 insertions(+) >>> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >>> index 2ededa7f43df..b5f047b5f3ae 100644 >>> --- a/drivers/mmc/host/sdhci.c >>> +++ b/drivers/mmc/host/sdhci.c >>> @@ -3672,6 +3672,7 @@ int sdhci_setup_host(struct sdhci_host *host) >>> if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V) { >>> host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 | >>> SDHCI_SUPPORT_DDR50); >>> + mmc->caps2 &= ~MMC_CAP2_HSX00_1_8V; >> >> Seems weird for sdhci to clear flags it never set. Also couldn't we >> reasonably expect dt properties to be consistent? Is this really about >> setting SDHCI_QUIRK2_NO_1_8_V in your driver and expecting it to override >> other dt properties? Although that still begs the question why anyone would >> set dt properties that the hardware doesn't support? I guess you should >> also clear MMC_CAP2_HS400_ES. > > The SoC might support a specific mode like HS200. So the SoC specific dtsi file > might have dt properties for HS200 mode set. But the board which uses the SoC > might be modeled in a way a particular mode cannot be used (like IO lines not > connected to 1.8v). One option is to use /delete-property/ in the board dts > file. But since "no-1-8-v" property already indicates HS200 mode cannot be > supported, having a /delete-property/ might be redundant. > > I can reset caps2 in sdhci-omap after invoking mmc_of_parse if you feel that > makes more sense. Just add the explanation to the commit message, add a comment to the code, and also clear MMC_CAP_1_8V_DDR and MMC_CAP2_HS400_ES and MMC_CAP_UHS_*.