From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Westerberg, Mika" Subject: Re: [PATCH] i2c-designware: Mask interrupts during i2c controller enable Date: Mon, 7 Apr 2014 18:11:08 +0300 Message-ID: <20140407151107.GL19349@intel.com> References: <7286EAF50D3F4E4AADE7FEECEBF8B5A537A70E1F@ORSMSX109.amr.corp.intel.com> <20140404181613.GB19349@intel.com> <7286EAF50D3F4E4AADE7FEECEBF8B5A537A70F8B@ORSMSX109.amr.corp.intel.com> <20140404184232.GC19349@intel.com> <7286EAF50D3F4E4AADE7FEECEBF8B5A537A71351@ORSMSX109.amr.corp.intel.com> <20140405061316.GF19349@intel.com> <20140406185818.3aaca03d@alan.etchedpixels.co.uk> <20140407090403.GG19349@intel.com> <20140407154252.6b8f0f7e@alan.etchedpixels.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20140407154252.6b8f0f7e@alan.etchedpixels.co.uk> Sender: linux-kernel-owner@vger.kernel.org To: One Thousand Gnomes Cc: "Du, Wenkai" , "linux-i2c@vger.kernel.org" , Wolfram Sang , "linux-kernel@vger.kernel.org" List-Id: linux-i2c@vger.kernel.org On Mon, Apr 07, 2014 at 03:42:52PM +0100, One Thousand Gnomes wrote: > > I had to check BYT specs about that and I couldn't find if it does > > posted-writes. > > Then I would assume it does unless you can find a hardware engineer to > sign a statement in blood to that effect 8) Fair enough. > > Actually the following patch should fix the problem as well. Just move the > > HW enable to happen last. That way we can make sure that there is a valid > > interrupt mask programmed before the controller is enabled. > > This fixes the init case, it doesn't fix the question about returning > from the IRQ before the mask write takes effect and thus taking another > interrupt. Do you think we can fix it with adding a dummy read right after write to the mask register, like the snippet below? diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 14c4b30d4ccc..ff9090381d8b 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -535,6 +535,7 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev) intr_mask = 0; dw_writel(dev, intr_mask, DW_IC_INTR_MASK); + dw_readl(dev, DW_IC_INTR_MASK); } static void