From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH] i2c-pxa.c recover from false start Date: Thu, 19 Jun 2008 13:42:37 +0200 Message-ID: <20080619134237.3b7dff53@hyperion.delvare> References: <36A8B4824CA88E478F1A25136D0597610112DD04@mail.ad.skymv.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <36A8B4824CA88E478F1A25136D0597610112DD04-RKsfjrak5bi0VCHWTNMfawC/G2K4zDHf@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org Errors-To: i2c-bounces-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org To: Chuck Kamas Cc: i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org List-Id: linux-i2c@vger.kernel.org Hi Chuck, No HTML mails, please. On Tue, 17 Jun 2008 15:39:16 -0700, Chuck Kamas wrote: > I made this patch to recover from a false start on the bus. This > scenario happens in my system when a device is hot-inserted onto the bus > causing a false start. This is caused by the new device pulling SDA > low. The PXA then thinks someone is trying to talk on the bus and will > not transmit. My solution is to detect this fault and reset the pxa's > i2c subsystem... not nice I know. If there is a better way, let me > know! How do you differentiate between this case and another master starting a real transaction on the bus? What you have is a hardware issue. If you hotplug I2C devices, then you must ensure that they will not pull either SCL not SDA low when you do. Otherwise you are not only confusing the PXA master, but also quite possibly the other slaves on the I2C bus. Maybe you have to put the new device behind a gate, and open the gate once the device is properly connected and initialized (and likewise close the gate before you remove the device.) I think you have to fix your hardware setup, not the i2c-pxa driver. -- Jean Delvare _______________________________________________ i2c mailing list i2c-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org http://lists.lm-sensors.org/mailman/listinfo/i2c