Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755260AbbHKIdB (ORCPT ); Tue, 11 Aug 2015 04:33:01 -0400 Received: from mail-yk0-f180.google.com ([209.85.160.180]:36124 "EHLO mail-yk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755158AbbHKIc6 (ORCPT ); Tue, 11 Aug 2015 04:32:58 -0400 MIME-Version: 1.0 In-Reply-To: <1438845731-17805-2-git-send-email-eddie.huang@mediatek.com> References: <1438845731-17805-1-git-send-email-eddie.huang@mediatek.com> <1438845731-17805-2-git-send-email-eddie.huang@mediatek.com> From: Daniel Kurtz Date: Tue, 11 Aug 2015 16:32:38 +0800 X-Google-Sender-Auth: KHanEeS5NHnwtgHxsxv9rMF7b2I Message-ID: Subject: Re: [PATCH v2 1/2] i2c: mediatek: Reset DMA engine in hardware init function To: Eddie Huang Cc: Wolfram Sang , srv_heupstream , Matthias Brugger , Liguo Zhang , Xudong Chen , Sascha Hauer , Linux I2C , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , linux-mediatek@lists.infradead.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2170 Lines: 57 On Thu, Aug 6, 2015 at 3:22 PM, Eddie Huang wrote: > Reset DMA in hardware init function to avoid unknown hardware state > before do any I2C operation. > > Signed-off-by: Liguo Zhang > Signed-off-by: Eddie Huang Reviewed-by: Daniel Kurtz > --- > drivers/i2c/busses/i2c-mt65xx.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c > index 9920eef..e28ad4c 100644 > --- a/drivers/i2c/busses/i2c-mt65xx.c > +++ b/drivers/i2c/busses/i2c-mt65xx.c > @@ -59,6 +59,7 @@ > #define I2C_DMA_START_EN 0x0001 > #define I2C_DMA_INT_FLAG_NONE 0x0000 > #define I2C_DMA_CLR_FLAG 0x0000 > +#define I2C_DMA_HARD_RST 0x0002 > > #define I2C_DEFAULT_SPEED 100000 /* hz */ > #define MAX_FS_MODE_SPEED 400000 > @@ -81,6 +82,7 @@ enum DMA_REGS_OFFSET { > OFFSET_INT_FLAG = 0x0, > OFFSET_INT_EN = 0x04, > OFFSET_EN = 0x08, > + OFFSET_RST = 0x0c, > OFFSET_CON = 0x18, > OFFSET_TX_MEM_ADDR = 0x1c, > OFFSET_RX_MEM_ADDR = 0x20, > @@ -262,6 +264,10 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c) > I2C_CONTROL_CLK_EXT_EN | I2C_CONTROL_DMA_EN; > writew(control_reg, i2c->base + OFFSET_CONTROL); > writew(I2C_DELAY_LEN, i2c->base + OFFSET_DELAY_LEN); > + > + writel(I2C_DMA_HARD_RST, i2c->pdmabase + OFFSET_RST); > + udelay(50); > + writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_RST); > } > > /* > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/