From: grygorii.strashko@ti.com (Grygorii Strashko)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] i2c: omap: fix bus recovery setup
Date: Tue, 14 Jul 2015 15:10:01 +0300 [thread overview]
Message-ID: <55A4FC19.4040709@ti.com> (raw)
In-Reply-To: <20150714111004.GB1517@katana>
Hi Wolfram,
On 07/14/2015 02:10 PM, Wolfram Sang wrote:
> On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote:
>> At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
>
> Felipe: it seems you did not need this; is this AM335x specific?
We need it (Felipe's reply can be delayed).
It's not AM335x specific. TMODE has to be configured for all OMAP4+ SoCs too.
>
>> allow direct access to the SCL and SDA pins. In addition to ST_EN, we
>> need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
>> Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
>> low level"), we need to set them to 1 (which means "high-impedance") to
>> avoid unwanted changes on the pins.
>>
>> As a precaution, reset all these bits to their default values after
>> recovery is complete.
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
>>
>> Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
>> ---
>> drivers/i2c/busses/i2c-omap.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
>> index d1c22e3fdd14..fc9bf7f30e35 100644
>> --- a/drivers/i2c/busses/i2c-omap.c
>> +++ b/drivers/i2c/busses/i2c-omap.c
>> @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
>> u32 reg;
>>
>> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
>> + /* enable test mode */
>> reg |= OMAP_I2C_SYSTEST_ST_EN;
>> + /* select SDA/SCL IO mode */
>> + reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
>> + /* set SCL to high-impedance state (reset value is 0) */
>> + reg |= OMAP_I2C_SYSTEST_SCL_O;
>> + /* set SDA to high-impedance state (reset value is 0) */
>> + reg |= OMAP_I2C_SYSTEST_SDA_O;
>> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
>> }
>>
>> @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
>> u32 reg;
>>
>> reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
>> + /* restore reset values */
>> reg &= ~OMAP_I2C_SYSTEST_ST_EN;
>> + reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
>> + reg &= ~OMAP_I2C_SYSTEST_SCL_O;
>> + reg &= ~OMAP_I2C_SYSTEST_SDA_O;
>> omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
>> }
>>
>> --
>> 2.1.4
>>
--
regards,
-grygorii
next prev parent reply other threads:[~2015-07-14 12:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 14:35 [PATCH] i2c: omap: fix bus recovery setup Jan Luebbe
2015-07-12 15:32 ` Alexander Sverdlin
2015-07-14 11:10 ` Wolfram Sang
2015-07-14 12:10 ` Grygorii Strashko [this message]
2015-07-14 12:12 ` Wolfram Sang
2015-07-29 10:27 ` Jan Lübbe
2015-07-31 10:49 ` Wolfram Sang
2015-07-31 10:51 ` Wolfram Sang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=55A4FC19.4040709@ti.com \
--to=grygorii.strashko@ti.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).