From: Viresh Kumar <viresh.kumar@linaro.org> To: Jie Deng <jie.deng@intel.com> Cc: Wolfram Sang <wsa@kernel.org>, linux-i2c@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mst@redhat.com, arnd@arndb.de, jasowang@redhat.com, andriy.shevchenko@linux.intel.com, yu1.wang@intel.com, shuo.a.liu@intel.com, conghui.chen@intel.com, stefanha@redhat.com Subject: Re: [PATCH v11] i2c: virtio: add a virtio i2c frontend driver Date: Fri, 2 Jul 2021 12:26:25 +0530 [thread overview] Message-ID: <20210702065625.qielhnfyrlvrtrkk@vireshk-i7> (raw) In-Reply-To: <409b6cc3-3339-61b2-7f42-0c69b6486bb3@intel.com> On 02-07-21, 14:52, Jie Deng wrote: > This is not efficient. If adding the ith request to the queue fails, we can > still send > > the requests before it. Not really. Normally the requests which are sent together by clients, are linked together, like a state machine. So if the first one is sent, but not the second one, then there is not going to be any meaningful result of that. The i2c core doesn't club requests together from different clients in a single i2c_transfer() call. So you must assume i2c_transfer(), irrespective of the number of underlying messages in it, as atomic. If you fail, the client is going to retry everything again or assume it failed completely. > We don't need to know if it fails here (adding to > the queue) > > or there (later in the host). The "master_xfer" just need to return final > number of > > messages successfully processed. No, that isn't going to help and it is rather inefficient, trying to send transfer when we already know part of it failed. -- viresh
WARNING: multiple messages have this Message-ID (diff)
From: Viresh Kumar <viresh.kumar@linaro.org> To: Jie Deng <jie.deng@intel.com> Cc: yu1.wang@intel.com, arnd@arndb.de, mst@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Wolfram Sang <wsa@kernel.org>, linux-i2c@vger.kernel.org, stefanha@redhat.com, shuo.a.liu@intel.com, andriy.shevchenko@linux.intel.com, conghui.chen@intel.com Subject: Re: [PATCH v11] i2c: virtio: add a virtio i2c frontend driver Date: Fri, 2 Jul 2021 12:26:25 +0530 [thread overview] Message-ID: <20210702065625.qielhnfyrlvrtrkk@vireshk-i7> (raw) In-Reply-To: <409b6cc3-3339-61b2-7f42-0c69b6486bb3@intel.com> On 02-07-21, 14:52, Jie Deng wrote: > This is not efficient. If adding the ith request to the queue fails, we can > still send > > the requests before it. Not really. Normally the requests which are sent together by clients, are linked together, like a state machine. So if the first one is sent, but not the second one, then there is not going to be any meaningful result of that. The i2c core doesn't club requests together from different clients in a single i2c_transfer() call. So you must assume i2c_transfer(), irrespective of the number of underlying messages in it, as atomic. If you fail, the client is going to retry everything again or assume it failed completely. > We don't need to know if it fails here (adding to > the queue) > > or there (later in the host). The "master_xfer" just need to return final > number of > > messages successfully processed. No, that isn't going to help and it is rather inefficient, trying to send transfer when we already know part of it failed. -- viresh _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-07-02 6:56 UTC|newest] Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-01 3:24 [PATCH v11] i2c: virtio: add a virtio i2c frontend driver Jie Deng 2021-07-01 3:24 ` Jie Deng 2021-07-01 4:04 ` Viresh Kumar 2021-07-01 4:04 ` Viresh Kumar 2021-07-01 6:10 ` Jie Deng 2021-07-01 6:10 ` Jie Deng 2021-07-01 6:18 ` Viresh Kumar 2021-07-01 6:18 ` Viresh Kumar 2021-07-02 3:36 ` Jie Deng 2021-07-02 3:36 ` Jie Deng 2021-07-02 4:56 ` Viresh Kumar 2021-07-02 4:56 ` Viresh Kumar 2021-07-01 19:24 ` Wolfram Sang 2021-07-02 4:55 ` Viresh Kumar 2021-07-02 4:55 ` Viresh Kumar 2021-07-02 6:22 ` Wolfram Sang 2021-07-02 6:52 ` Jie Deng 2021-07-02 6:52 ` Jie Deng 2021-07-02 6:56 ` Viresh Kumar [this message] 2021-07-02 6:56 ` Viresh Kumar 2021-07-02 7:11 ` Wolfram Sang 2021-07-02 7:15 ` Jie Deng 2021-07-02 7:15 ` Jie Deng 2021-07-02 7:21 ` Viresh Kumar 2021-07-02 7:21 ` Viresh Kumar 2021-07-02 7:36 ` Wolfram Sang 2021-07-01 8:50 ` kernel test robot 2021-07-01 8:50 ` kernel test robot 2021-07-01 8:50 ` kernel test robot 2021-07-01 10:00 ` kernel test robot 2021-07-01 10:00 ` kernel test robot 2021-07-01 10:00 ` kernel test robot 2021-07-02 3:12 ` Jie Deng 2021-07-02 3:12 ` Jie Deng 2021-07-02 3:12 ` Jie Deng 2021-07-02 6:38 ` [kbuild-all] " Rong Chen 2021-07-02 6:38 ` Rong Chen 2021-07-01 10:45 ` Andy Shevchenko 2021-07-01 10:45 ` Andy Shevchenko 2021-07-02 1:05 ` Jie Deng 2021-07-02 1:05 ` Jie Deng
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