From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jae Hyun Yoo Subject: Re: [PATCH i2c-next v9 0/5] i2c: aspeed: Add bus idle waiting logic for multi-master use cases Date: Tue, 15 Jan 2019 15:32:33 -0800 Message-ID: References: <20181030210917.32711-1-jae.hyun.yoo@linux.intel.com> <20190115224713.duoha332mjlrmwji@ninjato> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190115224713.duoha332mjlrmwji@ninjato> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Wolfram Sang Cc: Brendan Higgins , Rob Herring , Joel Stanley , Benjamin Herrenschmidt , Mark Rutland , Andrew Jeffery , linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, Jarkko Nikula , James Feist , Vernon Mauery List-Id: devicetree@vger.kernel.org On 1/15/2019 2:47 PM, Wolfram Sang wrote: > On Tue, Oct 30, 2018 at 02:09:11PM -0700, Jae Hyun Yoo wrote: >> In multi-master environment, this driver's master cannot know >> exactly when a peer master sends data to this driver's slave so a >> case can be happened that this master tries to send data through >> the master_xfer function but slave data from peer master is still >> being processed by this driver. To prevent state corruption in the >> case, this patch adds checking code if any slave operation is >> ongoing and it waits up to the bus timeout duration before starting >> a master_xfer operation. >> >> To support this change, it introduces changes on i2c-core-base to >> make that able to read the bus timeout and master transfer retries >> count values from device tree properties. >> >> Please review this patch set. > > Marking this as "Changes requested". I think if the mutex approach > works, these patches become obsolete then. > Hi Wolfram, Thanks for your touching base. I made and tested a new patch in my local. Actually, I couldn't use a mutex because it should provide locking between driver context and interrupt context. Instead, after taking lots of experiments, I checked that idle waiting can be supported by this H/W so I didn't need to use any locking method in the driver code for multi-master handling. I'll submit a new patch tomorrow using a different thread. Please drop this patch set. Thanks, Jae