From: Alok Chauhan <alokc@nvidia.com>
To: Alok Chauhan <alokc@nvidia.com>,
Shubhrajyoti Datta <omaplinuxkernel@gmail.com>
Cc: "khali@linux-fr.org" <khali@linux-fr.org>,
"ben-linux@fluff.org" <ben-linux@fluff.org>,
Stephen Warren <swarren@nvidia.com>,
"olof@lixom.net" <olof@lixom.net>,
"bones@secretlab.ca" <bones@secretlab.ca>,
"paul.gortmaker@windriver.com" <paul.gortmaker@windriver.com>,
"dgreid@google.com" <dgreid@google.com>,
Laxman Dewangan <ldewangan@nvidia.com>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2] i2c: tegra: Add delay before reset the controller
Date: Thu, 8 Mar 2012 11:59:23 +0530 [thread overview]
Message-ID: <7A0BFCFE3DA5CD47B0FB7984326F201A136B886672@BGMAIL01.nvidia.com> (raw)
In-Reply-To: <7A0BFCFE3DA5CD47B0FB7984326F201A13689D386F@BGMAIL01.nvidia.com>
Hi all,
If there are no more concern then can we merge this patch to i2c tegra driver?
Thanks
Alok
On Mon, Dec 26, 2011 at 4:44 PM, Alok Chauhan <alokc@nvidia.com> wrote:
> From: Alok Chauhan <alokc@nvidia.com>
>
> In NACK error condition, I2C controller violates clock-to-data setup
> time before stop. In Software, because of this reset of controller is
> happening before I2C controller could complete STOP condition.
>
> Added delay of 2 clock period before reset the controller in case of
> NACK error.
>
> Signed-off-by: Alok Chauhan <alokc@nvidia.com>
> ---
> Instead of setting constant value for delay as was in previous patch,
> now in the current modification delay will be calculated based on clock frequency of the bus.
> drivers/i2c/busses/i2c-tegra.c | 8 ++++++++
> 1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c
> b/drivers/i2c/busses/i2c-tegra.c index 6381604..62e197c 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -517,6 +517,14 @@ static int tegra_i2c_xfer_msg(struct
> tegra_i2c_dev *i2c_dev,
> if (likely(i2c_dev->msg_err == I2C_ERR_NONE))
> return 0;
>
> + /*
> + * In NACK error condition resetting of I2C controller happens
> + * before STOP condition is properly completed by I2C
> + controller,
> + * so wait for 2 clock cycle to complete STOP condition.
> + */
>>>>Why do you need to reset the controller in case of a NACK.
>>>This is required because of hardware limitations. Without reset we can't flus the internal hardware registers.
> + if (i2c_dev->msg_err == I2C_ERR_NO_ACK)
> + udelay(DIV_ROUND_UP(2 * 1000000,
> + i2c_dev->bus_clk_rate));
> +
> tegra_i2c_init(i2c_dev);
> if (i2c_dev->msg_err == I2C_ERR_NO_ACK) {
> if (msg->flags & I2C_M_IGNORE_NAK)
> --
> 1.7.4.1
>
> --
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next prev parent reply other threads:[~2012-03-08 6:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-26 11:14 [PATCH v2] i2c: tegra: Add delay before reset the controller Alok Chauhan
2012-01-06 16:18 ` Ben Dooks
2012-01-10 4:12 ` Alok Chauhan
2012-02-10 9:20 ` Alok Chauhan
2012-02-10 9:35 ` Shubhrajyoti Datta
2012-02-14 5:49 ` Alok Chauhan
2012-03-08 6:29 ` Alok Chauhan [this message]
2012-04-02 5:53 Alok Chauhan
2012-04-02 5:59 ` Alok Chauhan
2012-04-02 10:19 ` Shubhrajyoti Datta
2012-04-02 12:06 ` Alok Chauhan
2012-04-02 19:58 ` Stephen Warren
2012-04-13 22:51 ` Stephen Warren
2012-04-18 14:27 ` Wolfram Sang
2012-04-18 20:02 ` Stephen Warren
2012-04-18 20:20 ` Wolfram Sang
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