From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933269Ab2GYPIY (ORCPT ); Wed, 25 Jul 2012 11:08:24 -0400 Received: from mail.work-microwave.de ([62.245.205.51]:37677 "EHLO work-microwave.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933160Ab2GYPIQ (ORCPT ); Wed, 25 Jul 2012 11:08:16 -0400 From: Roland Stigge To: vitalywool@gmail.com, khali@linux-fr.org, ben-linux@fluff.org, w.sang@pengutronix.de, grant.likely@secretlab.ca, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, kevin.wells@nxp.com, srinivas.bakki@nxp.com, aletes.xgr@gmail.com, jonsmirl@gmail.com Cc: Roland Stigge Subject: [PATCH 2/2] i2c: pnx: Fix read transactions of >= 2 bytes Date: Wed, 25 Jul 2012 17:07:43 +0200 Message-Id: <1343228863-11553-2-git-send-email-stigge@antcom.de> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1343228863-11553-1-git-send-email-stigge@antcom.de> References: <1343228863-11553-1-git-send-email-stigge@antcom.de> X-FEAS-SYSTEM-WL: rst@work-microwave.de, 192.168.11.78 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On transactions with n>=2 bytes, the controller actually wrongly clocks in n+1 bytes. This is caused by the (wrong) assumption that RFE in the Status Register is 1 iff there is no byte already ordered (via a dummy TX byte). This lead to the implementation of synchronized byte ordering, e.g.: Dummy-TX - RX - Dummy-TX - RX - ... But since RFE actually stays high after some Dummy-TX, it rather looks like: Dummy-TX - Dummy-TX - RX - Dummy-TX - RX - (RX) The last RX byte is clocked in by the bus controller, but ignored by the kernel when filling the userspace buffer. This patch fixes the issue by asking for RX via Dummy-TX asynchronously. Introducing a separate counter for TX bytes. Signed-off-by: Roland Stigge --- Applies to v3.5 This patch for i2c-pnx applies to: PNX4008, LPC31xx, LPC32xx. Can you please test? Thanks in advance! drivers/i2c/busses/i2c-pnx.c | 48 +++++++++++++++++++++++++------------------ include/linux/i2c-pnx.h | 1 2 files changed, 29 insertions(+), 20 deletions(-) --- linux-2.6.orig/drivers/i2c/busses/i2c-pnx.c +++ linux-2.6/drivers/i2c/busses/i2c-pnx.c @@ -291,31 +291,37 @@ static int i2c_pnx_master_rcv(struct i2c * or we didn't 'ask' for it yet. */ if (ioread32(I2C_REG_STS(alg_data)) & mstatus_rfe) { - dev_dbg(&alg_data->adapter.dev, - "%s(): Write dummy data to fill Rx-fifo...\n", - __func__); + /* 'Asking' is done asynchronously, e.g. dummy TX of several + * bytes is done before the first actual RX arrives in FIFO. + * Therefore, ordered bytes (via TX) are counted separately. + */ + if (alg_data->mif.order) { + dev_dbg(&alg_data->adapter.dev, + "%s(): Write dummy data to fill Rx-fifo...\n", + __func__); - if (alg_data->mif.len == 1) { - /* Last byte, do not acknowledge next rcv. */ - val |= stop_bit; + if (alg_data->mif.order == 1) { + /* Last byte, do not acknowledge next rcv. */ + val |= stop_bit; + + /* + * Enable interrupt RFDAIE (data in Rx fifo), + * and disable DRMIE (need data for Tx) + */ + ctl = ioread32(I2C_REG_CTL(alg_data)); + ctl |= mcntrl_rffie | mcntrl_daie; + ctl &= ~mcntrl_drmie; + iowrite32(ctl, I2C_REG_CTL(alg_data)); + } /* - * Enable interrupt RFDAIE (data in Rx fifo), - * and disable DRMIE (need data for Tx) + * Now we'll 'ask' for data: + * For each byte we want to receive, we must + * write a (dummy) byte to the Tx-FIFO. */ - ctl = ioread32(I2C_REG_CTL(alg_data)); - ctl |= mcntrl_rffie | mcntrl_daie; - ctl &= ~mcntrl_drmie; - iowrite32(ctl, I2C_REG_CTL(alg_data)); + iowrite32(val, I2C_REG_TX(alg_data)); + alg_data->mif.order--; } - - /* - * Now we'll 'ask' for data: - * For each byte we want to receive, we must - * write a (dummy) byte to the Tx-FIFO. - */ - iowrite32(val, I2C_REG_TX(alg_data)); - return 0; } @@ -515,6 +521,7 @@ i2c_pnx_xfer(struct i2c_adapter *adap, s alg_data->mif.buf = pmsg->buf; alg_data->mif.len = pmsg->len; + alg_data->mif.order = pmsg->len; alg_data->mif.mode = (pmsg->flags & I2C_M_RD) ? I2C_SMBUS_READ : I2C_SMBUS_WRITE; alg_data->mif.ret = 0; @@ -567,6 +574,7 @@ i2c_pnx_xfer(struct i2c_adapter *adap, s /* Cleanup to be sure... */ alg_data->mif.buf = NULL; alg_data->mif.len = 0; + alg_data->mif.order = 0; dev_dbg(&alg_data->adapter.dev, "%s(): exiting, stat = %x\n", __func__, ioread32(I2C_REG_STS(alg_data))); --- linux-2.6.orig/include/linux/i2c-pnx.h +++ linux-2.6/include/linux/i2c-pnx.h @@ -22,6 +22,7 @@ struct i2c_pnx_mif { struct timer_list timer; /* Timeout */ u8 * buf; /* Data buffer */ int len; /* Length of data buffer */ + int order; /* RX Bytes to order via TX */ }; struct i2c_pnx_algo_data {