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From: Wolfram Sang <wsa@kernel.org>
To: Michael.Wu@vatics.com
Cc: jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com,
	mika.westerberg@linux.intel.com, linux-i2c@vger.kernel.org,
	linux-kernel@vger.kernel.org, morgan.chang@vatics.com
Subject: Re: [PATCH 2/2] i2c: designware: slave should do WRITE_REQUESTED before WRITE_RECEIVED
Date: Wed, 4 Nov 2020 11:35:31 +0100	[thread overview]
Message-ID: <20201104103531.GA3984@ninjato> (raw)
In-Reply-To: <5DB475451BAA174CB158B5E897FC1525B1295560@MBS07.vivotek.tw>

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> Not exactly. There're an interrupt state name "RD_REQ" but no one named
> like "WR_REQ".
> 
> For read-request, the slave will get a RD_REQ interrupt. 
> For write-request, the slave won't be interrupted until data arrived to
> trigger interrupt "RX_FULL".
> 
> I tried to use GPIO to simulate an I2C master. I only sent its own
> address + W bit without any data and then I got only a STOP_DET interrupt.
> If I sent its own address + W bit + one byte data and then I got one
> RX_FULL and a STOP_DET.
> 
> It seems the controller doesn't interrupt when RW bit is W, but R does.

Thanks for the detailed explanation! Okay, then what you do looks
correct to me (from a high level perspective without really knowing the
HW): when RX is full, you first send the state WRITE_REQUESTED when
there is no other transfer on-going. Then you send WRITE_RECEIVED
immediately. I think this is the way to do it.


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  reply	other threads:[~2020-11-04 10:35 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30  8:04 [PATCH 0/2] Designware I2C slave confusing IC_INTR_STOP_DET handle Michael Wu
2020-10-30  8:04 ` [PATCH 1/2] i2c: designware: call i2c_dw_read_clear_intrbits_slave() once Michael Wu
2020-10-30  8:04 ` [PATCH 2/2] i2c: designware: slave should do WRITE_REQUESTED before WRITE_RECEIVED Michael Wu
2020-10-30 14:46   ` Jarkko Nikula
2020-11-03 21:03   ` Wolfram Sang
2020-11-04 10:17     ` Michael.Wu
2020-11-04 10:35       ` Wolfram Sang [this message]
2020-11-04 10:51         ` Michael.Wu
2020-11-05  9:13       ` Jarkko Nikula
  -- strict thread matches above, loose matches on Subject: below --
2020-10-16  6:04 [PATCH 1/2] i2c: designware: call i2c_dw_read_clear_intrbits_slave() once Michael Wu
2020-10-16  6:04 ` [PATCH 2/2] i2c: designware: slave should do WRITE_REQUESTED before WRITE_RECEIVED Michael Wu

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