linux-kernel - Re: [PATCH 8/8] phy: add driver for TI TUSB1210 ULPI PHY

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Message-ID: <20150213015242.GD21337@psi-dev26.jf.intel.com>
Date:	Thu, 12 Feb 2015 17:52:42 -0800
From:	David Cohen <david.a.cohen@...ux.intel.com>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Baolu Lu <baolu.lu@...ux.intel.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kishon Vijay Abraham I <kishon@...com>
Subject: Re: [PATCH 8/8] phy: add driver for TI TUSB1210 ULPI PHY

Hi Heikki,

Sorry I am starting a new branch on this thread.
I need to go back to another topic on this same patch.

On Fri, Jan 23, 2015 at 05:12:58PM +0200, Heikki Krogerus wrote:
> TUSB1210 ULPI PHY has vendor specific register for eye
> diagram tuning. On some platforms the system firmware has
> set optimized value to it. In order to not loose the
> optimized value, the driver stores it during probe and
> restores it every time the PHY is powered back on.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Cc: Kishon Vijay Abraham I <kishon@...com>
> ---

[snip]

> +	/* Store initial eye diagram optimisation value */
> +	ret = ulpi_read(ulpi, TUSB1210_VENDOR_SPECIFIC2);

We can't rely on eye diagram optimization value here. It's possible the
phy went through reset (e.g. module unloading/loading).
We need a more consistent method. Could we use _DSD instead? That would
be more compatible with DT too.

Br, David

> +	if (ret < 0)
> +		return ret;
> +
> +	tusb->eye_diagram_tuning = ret;
> +
> +	tusb->phy = ulpi_phy_create(ulpi, &phy_ops);
> +	if (IS_ERR(tusb->phy))
> +		return PTR_ERR(tusb->phy);
> +
> +	tusb->ulpi = ulpi;
> +
> +	phy_set_drvdata(tusb->phy, tusb);
> +	ulpi_set_drvdata(ulpi, tusb);
> +	return 0;
> +}
> +
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