Re: [PATCH v2 1/2] Input: mms114 - add support for mms345l

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Stephan,

On Sun, Apr 05, 2020 at 07:09:03PM +0200, Stephan Gerhold wrote:
> MMS345L is another first generation touch screen from Melfas,
> which uses the same registers as MMS152.
> 
> However, using I2C_M_NOSTART for it causes errors when reading:
> 
> 	i2c i2c-0: sendbytes: NAK bailout.
> 	mms114 0-0048: __mms114_read_reg: i2c transfer failed (-5)
> 
> The driver works fine as soon as I2C_M_NOSTART is removed.
> 
> Add a separate melfas,mms345l binding, and make use of I2C_M_NOSTART
> only for MMS114 and MMS152.
> 
> Reviewed-by: Andi Shyti <andi@etezian.org>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>

Sorry for sitting on this for so long. I looked around, and I think that
instead of adding separate handling for 345L we shoudl simply drop the
"no start" bit for everyone. I am not sure what the original version
tried to do here, as far as I can see in various public Android trees the
driver for these devices does not use I2C_M_NOSTART.

Actually, I wonder if the difference is not in the touch controller that
is being used, but rather in the I2C controller the device in connected
to.

I would like to apply the version of the patch below.

Thanks.

-- 
Dmitry


Input: mms114 - fix handling of mms345l

From: Stephan Gerhold <stephan@gerhold.net>

MMS345L is another first generation touch screen from Melfas,
which uses the same registers as MMS152.

However, using I2C_M_NOSTART for it causes errors when reading:

	i2c i2c-0: sendbytes: NAK bailout.
	mms114 0-0048: __mms114_read_reg: i2c transfer failed (-5)

The driver works fine as soon as I2C_M_NOSTART is removed.

Reviewed-by: Andi Shyti <andi@etezian.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20200405170904.61512-1-stephan@gerhold.net
Patchwork-Id: 11474771
[dtor: removed separate mms345l handling, made everyone use standard
transfer mode, propagated the 10bit addressing flag to the read part of the
transfer as well.]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/touchscreen/mms114.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/input/touchscreen/mms114.c b/drivers/input/touchscreen/mms114.c
index 69c6d559eeb0..2ef1adaed9af 100644
--- a/drivers/input/touchscreen/mms114.c
+++ b/drivers/input/touchscreen/mms114.c
@@ -91,15 +91,15 @@ static int __mms114_read_reg(struct mms114_data *data, unsigned int reg,
 	if (reg <= MMS114_MODE_CONTROL && reg + len > MMS114_MODE_CONTROL)
 		BUG();
 
-	/* Write register: use repeated start */
+	/* Write register */
 	xfer[0].addr = client->addr;
-	xfer[0].flags = I2C_M_TEN | I2C_M_NOSTART;
+	xfer[0].flags = client->flags & I2C_M_TEN;
 	xfer[0].len = 1;
 	xfer[0].buf = &buf;
 
 	/* Read data */
 	xfer[1].addr = client->addr;
-	xfer[1].flags = I2C_M_RD;
+	xfer[1].flags = (client->flags & I2C_M_TEN) | I2C_M_RD;
 	xfer[1].len = len;
 	xfer[1].buf = val;
 
@@ -428,10 +428,8 @@ static int mms114_probe(struct i2c_client *client,
 	const void *match_data;
 	int error;
 
-	if (!i2c_check_functionality(client->adapter,
-				I2C_FUNC_PROTOCOL_MANGLING)) {
-		dev_err(&client->dev,
-			"Need i2c bus that supports protocol mangling\n");
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "Not supported I2C adapter\n");
 		return -ENODEV;
 	}