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From:   "Ardelean, Alexandru" <alexandru.Ardelean@analog.com>
To:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
CC:     "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        David Jander <david@protonic.nl>
Subject: RE: [PATCH v1] Input: ads7846: do not overwrite spi->mode flags set
 by spi framework
Thread-Topic: [PATCH v1] Input: ads7846: do not overwrite spi->mode flags set
 by spi framework
Thread-Index: AQHWp4k2cK6BoHhI0ka16h4hruuU+qmhyJ2g
Date:   Wed, 21 Oct 2020 09:29:35 +0000
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References: <20201021090434.16387-1-o.rempel@pengutronix.de>
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> -----Original Message-----
> From: Oleksij Rempel <o.rempel@pengutronix.de>
> Sent: Wednesday, October 21, 2020 12:05 PM
> To: Dmitry Torokhov <dmitry.torokhov@gmail.com>; Ardelean, Alexandru
> <alexandru.Ardelean@analog.com>
> Cc: Oleksij Rempel <o.rempel@pengutronix.de>; kernel@pengutronix.de; linu=
x-
> kernel@vger.kernel.org; linux-input@vger.kernel.org; David Jander
> <david@protonic.nl>
> Subject: [PATCH v1] Input: ads7846: do not overwrite spi->mode flags set =
by spi
> framework
>=20
> [External]
>=20
> Do not overwrite spi->mode flags set by spi framework, otherwise the chip
> select polarity will get lost.
>=20
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  drivers/input/touchscreen/ads7846.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/input/touchscreen/ads7846.c
> b/drivers/input/touchscreen/ads7846.c
> index 8fd7fc39c4fd..ea31956f3a90 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -1288,7 +1288,7 @@ static int ads7846_probe(struct spi_device *spi)
>  	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
>  	 */
>  	spi->bits_per_word =3D 8;
> -	spi->mode =3D SPI_MODE_0;

I think the patch is incorrect.
The initial version is correct; assuming that the datasheet says that this =
driver operates in mode 0.
If the initial mode is incorrect, maybe we need to change that.

What is unfortunate, is that you cannot [yet] override the mode parameters =
[polarity & phase] from the device-tree, in case there are some things in-b=
etween the SPI controller & SPI chip [level inverters for example].
I was planning to do something for this.

> +	spi->mode |=3D SPI_MODE_0;
>  	err =3D spi_setup(spi);
>  	if (err < 0)
>  		return err;
> --
> 2.28.0