Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757677Ab3EVWQ3 (ORCPT ); Wed, 22 May 2013 18:16:29 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:42120 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757467Ab3EVWKo (ORCPT ); Wed, 22 May 2013 18:10:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Ahmad , Mika Westerberg , Wolfram Sang Subject: [ 05/21] i2c: designware: fix RX FIFO overrun Date: Wed, 22 May 2013 15:10:23 -0700 Message-Id: <20130522205233.296977725@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130522205232.597066680@linuxfoundation.org> References: <20130522205232.597066680@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3069 Lines: 93 3.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Ahmad commit e6f34cea56f5b95498070eaa9f4aa3ba4a9e4f62 upstream. i2c_dw_xfer_msg() pushes a number of bytes to transmit/receive to/from the bus into the TX FIFO. For master-rx transactions, the maximum amount of data that can be received is calculated depending solely on TX and RX FIFO load. This is racy - TX FIFO may contain master-rx data yet to be processed, which will eventually land into the RX FIFO. This data is not taken into account and the function may request more data than the controller is actually capable of storing. This patch ensures the driver takes into account the outstanding master-rx data in TX FIFO to prevent RX FIFO overrun. Signed-off-by: Josef Ahmad Acked-by: Mika Westerberg Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/busses/i2c-designware-core.c | 11 ++++++++++- drivers/i2c/busses/i2c-designware-core.h | 2 ++ 2 files changed, 12 insertions(+), 1 deletion(-) --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -426,8 +426,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev) cmd |= BIT(9); if (msgs[dev->msg_write_idx].flags & I2C_M_RD) { + + /* avoid rx buffer overrun */ + if (rx_limit - dev->rx_outstanding <= 0) + break; + dw_writel(dev, cmd | 0x100, DW_IC_DATA_CMD); rx_limit--; + dev->rx_outstanding++; } else dw_writel(dev, cmd | *buf++, DW_IC_DATA_CMD); tx_limit--; buf_len--; @@ -480,8 +486,10 @@ i2c_dw_read(struct dw_i2c_dev *dev) rx_valid = dw_readl(dev, DW_IC_RXFLR); - for (; len > 0 && rx_valid > 0; len--, rx_valid--) + for (; len > 0 && rx_valid > 0; len--, rx_valid--) { *buf++ = dw_readl(dev, DW_IC_DATA_CMD); + dev->rx_outstanding--; + } if (len > 0) { dev->status |= STATUS_READ_IN_PROGRESS; @@ -539,6 +547,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, st dev->msg_err = 0; dev->status = STATUS_IDLE; dev->abort_source = 0; + dev->rx_outstanding = 0; ret = i2c_dw_wait_bus_not_busy(dev); if (ret < 0) --- a/drivers/i2c/busses/i2c-designware-core.h +++ b/drivers/i2c/busses/i2c-designware-core.h @@ -60,6 +60,7 @@ * @adapter: i2c subsystem adapter node * @tx_fifo_depth: depth of the hardware tx fifo * @rx_fifo_depth: depth of the hardware rx fifo + * @rx_outstanding: current master-rx elements in tx fifo */ struct dw_i2c_dev { struct device *dev; @@ -88,6 +89,7 @@ struct dw_i2c_dev { u32 master_cfg; unsigned int tx_fifo_depth; unsigned int rx_fifo_depth; + int rx_outstanding; }; #define ACCESS_SWAP 0x00000001 -- 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/