linux-kernel - Re: [PATCH v6 07/15] platform/x86: int3472: Enable I2c daisy chain

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Message-ID: <YaAel9HuAvemRg2s@pendragon.ideasonboard.com>
Date:   Fri, 26 Nov 2021 01:39:03 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Mark Gross <markgross@...nel.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Len Brown <lenb@...nel.org>,
        linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kate Hsuan <hpa@...hat.com>, linux-media@...r.kernel.org,
        linux-clk@...r.kernel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v6 07/15] platform/x86: int3472: Enable I2c daisy chain

Hi Hans,

Thank you for the patch.

On Thu, Nov 25, 2021 at 05:54:04PM +0100, Hans de Goede wrote:
> From: Daniel Scally <djrscally@...il.com>
> 
> The TPS68470 PMIC has an I2C passthrough mode through which I2C traffic
> can be forwarded to a device connected to the PMIC as though it were
> connected directly to the system bus. Enable this mode when the chip
> is initialised.

Is there any drawback doing this unconditionally, if nothing is
connected to the bus on the other side (including no pull-ups) ?

> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Daniel Scally <djrscally@...il.com>
> ---
>  .../x86/intel/int3472/intel_skl_int3472_tps68470.c         | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/int3472/intel_skl_int3472_tps68470.c b/drivers/platform/x86/intel/int3472/intel_skl_int3472_tps68470.c
> index c05b4cf502fe..42e688f4cad4 100644
> --- a/drivers/platform/x86/intel/int3472/intel_skl_int3472_tps68470.c
> +++ b/drivers/platform/x86/intel/int3472/intel_skl_int3472_tps68470.c
> @@ -45,6 +45,13 @@ static int tps68470_chip_init(struct device *dev, struct regmap *regmap)
>  		return ret;
>  	}
>  
> +	/* Enable I2C daisy chain */
> +	ret = regmap_write(regmap, TPS68470_REG_S_I2C_CTL, 0x03);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable i2c daisy chain\n");
> +		return ret;
> +	}
> +
>  	dev_info(dev, "TPS68470 REVID: 0x%02x\n", version);
>  
>  	return 0;

-- 
Regards,

Laurent Pinchart