Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861AbaK2VAo (ORCPT ); Sat, 29 Nov 2014 16:00:44 -0500 Received: from mail-lb0-f173.google.com ([209.85.217.173]:43472 "EHLO mail-lb0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751800AbaK2VAV (ORCPT ); Sat, 29 Nov 2014 16:00:21 -0500 From: Alexander Kochetkov To: Kevin Hilman , Tony Lindgren , Felipe Balbi , Wolfram Sang , Alexander Kochetkov Cc: linux-omap@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC 2/2] i2c: omap: show that the reason of system lockup is an unhandled ISR event Date: Sun, 30 Nov 2014 01:00:03 +0400 Message-Id: <1417294803-14729-3-git-send-email-al.kochet@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1417294803-14729-1-git-send-email-al.kochet@gmail.com> References: <1417294803-14729-1-git-send-email-al.kochet@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 079d8af24b948261e1dae5d7df6b31b7bf205cb4 ("i2c: omap: bus: add a receiver flag") changed ISR loop to silently ignore unwanted XDR/XRDY or RDR/RRDY events without processing. That unwanted events will fire interrupt again and most likely they will be ignored again. As a result, system enters lockup state. CPU loops through omap_i2c_isr() and omap_i2c_isr_thread(). The lockup is signaled with the message "sched: RT throttling activated" shown on console. The commit allow unwanted events to enter into processing loop and to be acked (at least) and processed (show error message). Sometimes if unwannted event is acked, the ISR can continue it's work. Sometimes system still remains in the lockup, but at least the reason is obvious. That unwanted events I tested with are events from IP slave receiver, fired when General Call (GC) command is detected on the bus. As after every master transfer IP enter into slave receiver mode. ISR must be ready for events from slave receiver or slave receiver must be disabled after master transfer to avoid lockups. Signed-off-by: Alexander Kochetkov Fixes 079d8af24b948261e1dae5d7df6b31b7bf205cb4 "i2c: omap: bus: add a receiver flag" --- drivers/i2c/busses/i2c-omap.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index e890295..192f9ce 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -939,6 +939,22 @@ static void omap_i2c_receive_data(struct omap_i2c_dev *dev, u8 num_bytes, bool is_rdr) { u16 w; + int warn = 0; + + if (unlikely(!dev->receiver)) { + warn = 1; + /* REVISIT: errata i207 during transmission? */ + if (dev->errata & I2C_OMAP_ERRATA_I207) { + if (is_rdr & !num_bytes) + warn = 0; + } + num_bytes = 0; + } + + if (unlikely(warn)) { + dev_err(dev->dev, "%s interrupt while sending\n", + is_rdr ? "RDR" : "RRDY"); + } if (unlikely(num_bytes > dev->buf_len)) { dev_err(dev->dev, "%s interrupt can't receive %u byte(s)\n", @@ -971,6 +987,12 @@ static int omap_i2c_transmit_data(struct omap_i2c_dev *dev, u8 num_bytes, { u16 w; + if (unlikely(dev->receiver)) { + dev_err(dev->dev, "%s interrupt while receiving\n", + is_xdr ? "XDR" : "XRDY"); + num_bytes = 0; + } + if (unlikely(num_bytes > dev->buf_len)) { dev_err(dev->dev, "%s interrupt can't transmit %u byte(s)\n", is_xdr ? "XDR" : "XRDY", (num_bytes - dev->buf_len)); @@ -1043,12 +1065,6 @@ omap_i2c_isr_thread(int this_irq, void *dev_id) stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); stat &= bits; - /* If we're in receiver mode, ignore XDR/XRDY */ - if (dev->receiver) - stat &= ~(OMAP_I2C_STAT_XDR | OMAP_I2C_STAT_XRDY); - else - stat &= ~(OMAP_I2C_STAT_RDR | OMAP_I2C_STAT_RRDY); - if (!stat) { /* my work here is done */ goto out; -- 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/