Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934078Ab3E3P4t (ORCPT ); Thu, 30 May 2013 11:56:49 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:57173 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757686Ab3E3P41 (ORCPT ); Thu, 30 May 2013 11:56:27 -0400 From: Oleksandr Dmytryshyn To: Tony Lindgren , Wolfram Sang CC: , , Subject: [PATCH v2 0/1] i2c: omap: correct usage of the interrupt enable register Date: Thu, 30 May 2013 18:56:18 +0300 Message-ID: <1369929379-19165-1-git-send-email-oleksandr.dmytryshyn@ti.com> X-Mailer: git-send-email 1.8.2.rc2 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1879 Lines: 49 I've just added a detailed description of the problem that is being solved to the cover letter and commit message in the patch. If the i2c controller during suspend will generate an interrupt, it can lead to unpredictable behaviour in the kernel. Based on the logic of the kernel code interrupts from i2c should be prohibited during suspend. Kernel writes 0 to the I2C_IE register in the omap_i2c_runtime_suspend() function. In the other side kernel writes saved interrupt flags to the I2C_IE register in omap_i2c_runtime_resume() function. I.e. interrupts should be disabled during suspend. This works for chips with version1 registers scheme. Interrupts are disabled during suspend. For chips with version2 scheme registers writting 0 to the I2C_IE register does nothing (because now the I2C_IRQENABLE_SET register is located at this address). This register is used to enable interrupts. For disabling interrupts I2C_IRQENABLE_CLR register should be used. Because the registers I2C_IRQENABLE_SET and I2C_IE have the same addresses, the interrupt enabling procedure is unchanged. I've checked that interrupts in the i2c controller are still enabled after writting 0 to the I2C_IE register. But with my patch interrupts are disabled in the omap_i2c_runtime_suspend() function. Next patch fixes it. Patch is based on: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git tag: v3.10-rc2 Verified on OMAP4430. Oleksandr Dmytryshyn (1): i2c: omap: correct usage of the interrupt enable register drivers/i2c/busses/i2c-omap.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) -- 1.8.2.rc2 -- 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/