linux-kernel - RE: [PATCH v4 5/8] MFD: ti_am335x

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Date:	Thu, 31 Jan 2013 04:11:11 +0000
From:	"Patil, Rachna" <rachna@...com>
To:	Koen Kooi <koen@...inion.thruhere.net>
CC:	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Dmitry Torokhov <dtor@...l.ru>,
	Rob Herring <rob.herring@...xeda.com>,
	Jonathan Cameron <jic23@....ac.uk>,
	Tony Lindgren <tony@...mide.com>,
	"Cousson, Benoit" <b-cousson@...com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Landley <rob@...dley.net>,
	Russell King <linux@....linux.org.uk>,
	"Hebbar, Gururaja" <gururaja.hebbar@...com>
Subject: RE: [PATCH v4 5/8] MFD: ti_am335x_tscadc: Add DT support

On Wed, Jan 30, 2013 at 16:10:09, Koen Kooi wrote:
> 
> Op 24 jan. 2013, om 04:45 heeft "Patil, Rachna" <rachna@...com> het volgende geschreven:
> 
> > From: "Patil, Rachna" <rachna@...com>
> > 
> > Make changes to add DT support in the MFD core driver.
> > 
> > Signed-off-by: Patil, Rachna <rachna@...com>
> > ---
> > Changes in v4:
> > 	Non-standard properties prefixed with vendor name.
> > 
> > drivers/mfd/ti_am335x_tscadc.c |   28 +++++++++++++++++++++++-----
> > 1 file changed, 23 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/mfd/ti_am335x_tscadc.c 
> > b/drivers/mfd/ti_am335x_tscadc.c index e9f3fb5..87b446b 100644
> > --- a/drivers/mfd/ti_am335x_tscadc.c
> > +++ b/drivers/mfd/ti_am335x_tscadc.c
> > @@ -22,6 +22,8 @@
> > #include <linux/regmap.h>
> > #include <linux/mfd/core.h>
> > #include <linux/pm_runtime.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > 
> > #include <linux/mfd/ti_am335x_tscadc.h> #include 
> > <linux/input/ti_am335x_tsc.h>
> > @@ -64,20 +66,31 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> > 	struct resource		*res;
> > 	struct clk		*clk;
> > 	struct mfd_tscadc_board	*pdata = pdev->dev.platform_data;
> > +	struct device_node	*node = pdev->dev.of_node;
> > 	struct mfd_cell		*cell;
> > 	int			err, ctrl;
> > 	int			clk_value, clock_rate;
> > -	int			tsc_wires, adc_channels = 0, total_channels;
> > +	int			tsc_wires = 0, adc_channels = 0, total_channels;
> > 
> > -	if (!pdata) {
> > +	if (!pdata && !pdev->dev.of_node) {
> > 		dev_err(&pdev->dev, "Could not find platform data\n");
> > 		return -EINVAL;
> > 	}
> > 
> > -	if (pdata->adc_init)
> > -		adc_channels = pdata->adc_init->adc_channels;
> > +	if (pdev->dev.platform_data) {
> > +		if (pdata->tsc_init)
> > +			tsc_wires = pdata->tsc_init->wires;
> > +
> > +		if (pdata->adc_init)
> > +			adc_channels = pdata->adc_init->adc_channels;
> > +	} else {
> > +		node = of_find_node_by_name(pdev->dev.of_node, "tsc");
> > +		of_property_read_u32(node, "ti,wires", &tsc_wires);
> > +
> > +		node = of_find_node_by_name(pdev->dev.of_node, "adc");
> > +		of_property_read_u32(node, "ti,adc-channels", &adc_channels);
> > +	}
> 
> Since AM335x is DT only, why is there a platform data codepath and why is it the first branch it tries? And I guess the next question is related to the first: why doesn't it work when used with DT? When I copy over the nodes from the evm.dts to my board I get "tsc tsc: Missing platform data" in dmesg.

This IP came up 1st on AM335x, but it is not platform dependent. The driver can be used on other platforms where-in DT is not supported.
According to the maintainers platform data takes precedence over DT. Hence the order.

I do not see "Missing platform data" error msg in the latest driver. I am not able to trace from where this got populated.

> 
> What are the chances this driver will work when applied on top of 3.8-rcX? Has it even been tested with that? Has it been tested at all?

This driver has been tested on top of v3.8-rc3 on a AM335x EVM.

Regards,
Rachna

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