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From: Jie Deng <jie.deng@intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-i2c@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, wsa@kernel.org,
	wsa+renesas@sang-engineering.com, 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 11:36:45 +0800	[thread overview]
Message-ID: <34092cb2-03f9-231d-8769-4e45ed51c30f@intel.com> (raw)
In-Reply-To: <20210701061846.7u4zorimzpmb66v7@vireshk-i7>


On 2021/7/1 14:18, Viresh Kumar wrote:
> On 01-07-21, 14:10, Jie Deng wrote:
>> I think a fixed number of sgs will make things easier to develop backend.
> Yeah, but it looks awkward to send a message buffer which isn't used
> at all. From protocol's point of view, it just looks wrong/buggy.
>
> The backend can just look at the number of elements received, they
> can either be 2 (in case of zero-length) transfer, or 3 (for
> read/write) and any other number is invalid.
>

OK. Let's add the following two lines to make sure that msg_buf is only
sent when the msgs len is not zero. And backend judges whether it is
a zero-length request by checking the number of elements received.

  + if (msgs[i].len) {
            reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
            if (!reqs[i].buf)
                    break;

           sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);

           if (msgs[i].flags & I2C_M_RD)
                   sgs[outcnt + incnt++] = &msg_buf;
           else
                   sgs[outcnt++] = &msg_buf;
+}



WARNING: multiple messages have this Message-ID (diff)
From: Jie Deng <jie.deng@intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: yu1.wang@intel.com, arnd@arndb.de, mst@redhat.com,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, wsa@kernel.org,
	wsa+renesas@sang-engineering.com, 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 11:36:45 +0800	[thread overview]
Message-ID: <34092cb2-03f9-231d-8769-4e45ed51c30f@intel.com> (raw)
In-Reply-To: <20210701061846.7u4zorimzpmb66v7@vireshk-i7>


On 2021/7/1 14:18, Viresh Kumar wrote:
> On 01-07-21, 14:10, Jie Deng wrote:
>> I think a fixed number of sgs will make things easier to develop backend.
> Yeah, but it looks awkward to send a message buffer which isn't used
> at all. From protocol's point of view, it just looks wrong/buggy.
>
> The backend can just look at the number of elements received, they
> can either be 2 (in case of zero-length) transfer, or 3 (for
> read/write) and any other number is invalid.
>

OK. Let's add the following two lines to make sure that msg_buf is only
sent when the msgs len is not zero. And backend judges whether it is
a zero-length request by checking the number of elements received.

  + if (msgs[i].len) {
            reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
            if (!reqs[i].buf)
                    break;

           sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);

           if (msgs[i].flags & I2C_M_RD)
                   sgs[outcnt + incnt++] = &msg_buf;
           else
                   sgs[outcnt++] = &msg_buf;
+}


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  reply	other threads:[~2021-07-02  3:36 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 [this message]
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
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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