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From: Andrey Danin <danindrey@mail.ru>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
	ac100@lists.launchpad.net, Laxman Dewangan <ldewangan@nvidia.com>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Alexandre Courbot <gnurou@gmail.com>,
	Marc Dietrich <marvin24@gmx.de>
Subject: Re: [PATCH 1/3] i2c: tegra: implement slave mode
Date: Tue, 31 Mar 2015 09:25:38 +0300	[thread overview]
Message-ID: <551A3DE2.90806@mail.ru> (raw)
In-Reply-To: <20150129114155.GA9080@katana>

Hi,

Sorry for long delay.

And thanks for the quick review. It helped a lot!

On 29.01.2015 14:41, Wolfram Sang wrote:
> Hi,
>
>> Initialization code is based on NVEC driver.
>>
>> There is a HW bug in AP20 that was also mentioned in kernel sources
>> for Toshiba AC100.
>>
>> Signed-off-by: Andrey Danin <danindrey@mail.ru>
>
> Cool, thanks for the converison. While I usually like to only get the
> patches which I need to handle, please CC me to all patches next time. I
> am interested what changes were needed for the user of the slave
> framework, too.

Done. I sent v2 yesterday evening.
>
>> +static bool tegra_i2c_slave_isr(int irq, struct tegra_i2c_dev *i2c_dev)
>> +{
>> +	unsigned long status;
>> +	u8 value;
>> +
>> +	if (!i2c_dev->slave || !i2c_dev->slave->slave_cb)
>> +		return false;
>
> Can this happen?

Yes. I call slave ISR without any conditions from main ISR routine.
>
>> +	/* i2c master sends data to us */
>> +	if (is_write(status)) {
>> +		i2c_slave_event(i2c_dev->slave, I2C_SLAVE_REQ_WRITE_START,
>> +				NULL);
>
> Can this HW create an interrupt once the address detection + RW bit are
> received? Or only if a complete write has been received?

Tegra I2C generates one interrupt per byte (address or data) and one 
interrupt for stop bit.
>
>> +static int tegra_reg_slave(struct i2c_client *slave)
>> +{
>> +	struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
>> +
>> +	if (i2c_dev->slave)
>> +		return -EBUSY;
>> +
>> +	i2c_dev->slave = slave;
>> +
>> +	tegra_i2c_clock_enable(i2c_dev);
>> +
>> +	reset_control_assert(i2c_dev->rst);
>> +	udelay(2);
>> +	reset_control_deassert(i2c_dev->rst);
>
> Why do you need a reset when a slave gets registered?

I copied this code from nvec driver. Reset is done during I2C controller 
initialization. This reset is not needed. Thanks for pointing.
>
>> +
>> +	i2c_writel(i2c_dev, I2C_SL_CNFG_NEWSL, I2C_SL_CNFG);
>> +	i2c_writel(i2c_dev, 0x1E, I2C_SL_DELAY_COUNT);
>
> What does this magic number mean?

It's a default value. I created a constant for it.
>
>> +
>> +	i2c_writel(i2c_dev, slave->addr, I2C_SL_ADDR1);
>> +	i2c_writel(i2c_dev, 0, I2C_SL_ADDR2);
>
> Handling 10 bit addresses?

In v2.
>
>> +
>> +	return 0;
>> +}
>> +
>
>>   static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
>> @@ -679,6 +808,7 @@ static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
>>   	.has_single_clk_source = false,
>>   	.clk_divisor_hs_mode = 3,
>>   	.clk_divisor_std_fast_mode = 0,
>> +	.slave_read_start_delay = 0,
>
> No need to init to 0 IMO.
>
Ok.

  reply	other threads:[~2015-03-31  6:25 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-29  7:20 [PATCH 0/3] arm: tegra: implement NVEC driver using tegra i2c Andrey Danin
2015-01-29  7:20 ` [PATCH 1/3] i2c: tegra: implement slave mode Andrey Danin
2015-01-29  9:40   ` Marc Dietrich
2015-01-29 11:41   ` Wolfram Sang
2015-03-31  6:25     ` Andrey Danin [this message]
2015-01-29  7:20 ` [PATCH 2/3] staging/nvec: reimplement on top of tegra i2c driver Andrey Danin
2015-01-29  9:53   ` Marc Dietrich
2015-01-29  7:20 ` [PATCH 3/3] dt: paz00: define nvec as child of i2c bus Andrey Danin
2015-01-29 10:01   ` Marc Dietrich
2015-02-02 21:20   ` Stephen Warren
2015-03-31  6:40     ` Andrey Danin
2015-03-31 14:09       ` Stephen Warren
2015-03-31 15:46         ` Andrey Danin
2015-03-31 16:04           ` Andrey Danin
2015-04-01 17:28           ` Stephen Warren
2015-04-02  9:37             ` Marc Dietrich
2015-04-02 14:50               ` Stephen Warren

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