From: Wolfram Sang <wsa@the-dreams.de>
To: Sricharan R <sricharan@codeaurora.org>
Cc: devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org,
agross@codeaurora.org, linux-kernel@vger.kernel.org,
linux-i2c@vger.kernel.org, iivanov@mm-sol.com,
galak@codeaurora.org, dmaengine@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, andy.gross@linaro.org,
ntelkar@codeaurora.org, architt@codeaurora.org
Subject: Re: [PATCH V7 3/6] i2c: qup: Transfer each i2c_msg in i2c_msgs without a stop bit
Date: Sun, 24 Jan 2016 12:29:16 +0100 [thread overview]
Message-ID: <20160124112915.GA1775@katana> (raw)
In-Reply-To: <1453197766-18976-4-git-send-email-sricharan@codeaurora.org>
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Hi,
> "If this is the last message in a group, it is followed by a STOP.
> Otherwise it is followed by the next @i2c_msg transaction segment,
> beginning with a (repeated) START"
This is correct.
> So the expectation is that there is no 'STOP' bit inbetween individual
> i2c_msg segments with repeated 'START'. The QUP i2c hardware has no way
> to inform that there should not be a 'STOP' at the end of transaction.
> The only way to implement this is to coalesce all the i2c_msg in i2c_msgs
> in to one transaction and transfer them. Adding the support for the same.
So, there will not be a REP_START condition on the bus? I am sorry to
say that I can't accept this. A REP_START is a REP_START and nothing
else. There are devices which will get confused if there is no real
REP_START condition.
Without knowing the HW in detail, can't you implement I2C_M_NOSTART and
let the touchscreen driver use it via regmap? That would be the proper
way (from what I understand).
Regards,
Wolfram
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next prev parent reply other threads:[~2016-01-24 11:29 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 10:02 [PATCH V7 0/6] i2c: qup: Add support for v2 tags and bam dma Sricharan R
2016-01-19 10:02 ` [PATCH V7 1/6] i2c: qup: Change qup_wait_writeready function to use for all timeouts Sricharan R
2016-02-12 18:37 ` Wolfram Sang
2016-01-19 10:02 ` [PATCH V7 2/6] i2c: qup: Add V2 tags support Sricharan R
2016-02-12 18:37 ` Wolfram Sang
2016-01-19 10:02 ` [PATCH V7 3/6] i2c: qup: Transfer each i2c_msg in i2c_msgs without a stop bit Sricharan R
2016-01-24 11:29 ` Wolfram Sang [this message]
2016-01-28 4:57 ` Sricharan
2016-02-04 20:09 ` Wolfram Sang
2016-02-05 8:00 ` Sricharan
2016-02-12 18:38 ` Wolfram Sang
2016-01-19 10:02 ` [PATCH V7 4/6] i2c: qup: Add bam dma capabilities Sricharan R
2016-02-12 18:37 ` Wolfram Sang
2016-02-12 18:42 ` Wolfram Sang
2016-02-13 6:58 ` Sricharan
2016-02-22 12:24 ` Sricharan
2016-02-22 12:32 ` Wolfram Sang
2016-02-22 13:41 ` Sricharan
2016-01-19 10:02 ` [PATCH V7 5/6] dts: msm8974: Add blsp2_bam dma node Sricharan R
2016-03-25 23:17 ` Bjorn Andersson
2016-03-26 2:26 ` Andy Gross
2016-03-28 12:59 ` Sricharan
2016-01-19 10:02 ` [PATCH V7 6/6] dts: msm8974: Add dma channels for blsp2_i2c1 node Sricharan R
2016-01-19 10:14 ` [PATCH V7 0/6] i2c: qup: Add support for v2 tags and bam dma Sricharan
2016-01-24 11:33 ` Wolfram Sang
2016-01-28 5:27 ` Sricharan
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