Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751386AbcKAP75 (ORCPT ); Tue, 1 Nov 2016 11:59:57 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36656 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbcKAP66 (ORCPT ); Tue, 1 Nov 2016 11:58:58 -0400 From: "Leonardo G. Veiga" To: ulf.hansson@linaro.org Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, stefan@agner.ch, raul.munoz@toradex.com, leonardo.veiga@toradex.com Subject: [PATCH] sdhci-esdhc-imx: fix bus-width for 1-bit operation. Date: Tue, 1 Nov 2016 13:58:25 -0200 Message-Id: <1478015905-31262-1-git-send-email-leogveiga@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1500 Lines: 39 From: Leonardo Graboski Veiga The 1-bit operation mode, enabled by seeting the 'bus-width' property of the device tree 'esdhc' node to <1>, not work while using SD card. The behavior is only noticed when only the data pin 0 is connected to the hardware. A series of kernel errors are printed to the console, all of them returning the following error message followed by some explanation: mmcblk0: error -84 transferring data If four data lines are connected, it ignores the device-tree property and works in 4-bit mode of operation without errors. The hardware used for testing does not support 8-bit mode. Check the 'bus-width' property and if set to <1>, enable the SDHCI_QUIRK_FORCE_1_BIT_DATA quirk. Signed-off-by: Leonardo Graboski Veiga --- drivers/mmc/host/sdhci-esdhc-imx.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index c9fbc4c3..88d7d22 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -1003,6 +1003,10 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev, host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V; } + if (!of_property_read_u32(np, "bus-width", &boarddata->max_bus_width) + && boarddata->max_bus_width == 1) + host->quirks |= SDHCI_QUIRK_FORCE_1_BIT_DATA; + /* call to generic mmc_of_parse to support additional capabilities */ ret = mmc_of_parse(host->mmc); if (ret) -- 2.7.4