From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heikki Krogerus Subject: [PATCH] ACPI / LPSS: fix UART Auto Flow Control Date: Wed, 9 Oct 2013 09:49:20 +0300 Message-ID: <1381301360-5156-1-git-send-email-heikki.krogerus@linux.intel.com> Return-path: Received: from mga11.intel.com ([192.55.52.93]:21368 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751906Ab3JIGtW (ORCPT ); Wed, 9 Oct 2013 02:49:22 -0400 Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: chiau.ee.chew@intel.com, linux-acpi@vger.kernel.org There is an additional bit in the GENERAL register on newer silicon that needs to be set or UART's RTS pin fails to reflect the flow control settings in the Modem Control Register. This will fix an issue where the RTS pin of the UART stays always at 1.8V, regardless of the register settings. Signed-off-by: Heikki Krogerus --- drivers/acpi/acpi_lpss.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c index fb78bb9..d396101 100644 --- a/drivers/acpi/acpi_lpss.c +++ b/drivers/acpi/acpi_lpss.c @@ -30,6 +30,7 @@ ACPI_MODULE_NAME("acpi_lpss"); /* Offsets relative to LPSS_PRIVATE_OFFSET */ #define LPSS_GENERAL 0x08 #define LPSS_GENERAL_LTR_MODE_SW BIT(2) +#define LPSS_GENERAL_UART_RTS_OVRD BIT(3) #define LPSS_SW_LTR 0x10 #define LPSS_AUTO_LTR 0x14 #define LPSS_TX_INT 0x20 @@ -68,11 +69,16 @@ struct lpss_private_data { static void lpss_uart_setup(struct lpss_private_data *pdata) { - unsigned int tx_int_offset = pdata->dev_desc->prv_offset + LPSS_TX_INT; + unsigned int offset; u32 reg; - reg = readl(pdata->mmio_base + tx_int_offset); - writel(reg | LPSS_TX_INT_MASK, pdata->mmio_base + tx_int_offset); + offset = pdata->dev_desc->prv_offset + LPSS_TX_INT; + reg = readl(pdata->mmio_base + offset); + writel(reg | LPSS_TX_INT_MASK, pdata->mmio_base + offset); + + offset = pdata->dev_desc->prv_offset + LPSS_GENERAL; + reg = readl(pdata->mmio_base + offset); + writel(reg | LPSS_GENERAL_UART_RTS_OVRD, pdata->mmio_base + offset); } static struct lpss_device_desc lpt_dev_desc = { -- 1.8.4.rc3