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Date: Thu, 9 Jun 2011 11:05:21 +0200
From: David Jander <david.jander@...tonic.nl>
To: Grant Likely <grant.likely@...retlab.ca>
Cc: David Jander <david@...tonic.nl>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/6] GPIO: pca953x.c: Remove meaningless device-tree
bindings
On Wed, 8 Jun 2011 11:08:57 -0600
Grant Likely <grant.likely@...retlab.ca> wrote:
> On Wed, Jun 08, 2011 at 02:48:31PM +0200, David Jander wrote:
> > The property 'polarity' is handled by the GPIO core, and the 'gpio-base'
> > should be assigned automatically. It is meaningless in the device-tree,
> > since GPIO's are identified by the "chip-name"/offset pair.
> > This way, the whole pca953x_get_alt_pdata() can go away.
> > We still need to check whether we really want GPIO-interrupt functionality
> > by simply looking if the I2C node has an interrupts property defined, since
> > this property is not used for anything else.
> >
> > Signed-off-by: David Jander <david@...tonic.nl>
> > ---
> > drivers/gpio/pca953x.c | 62
> > ++++++++--------------------------------------- 1 files changed, 11
> > insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
> > index 2dff562..ae9fe61 100644
> > --- a/drivers/gpio/pca953x.c
> > +++ b/drivers/gpio/pca953x.c
> > @@ -21,7 +21,6 @@
> > #include <linux/slab.h>
> > #ifdef CONFIG_OF_GPIO
> > #include <linux/of_platform.h>
> > -#include <linux/of_gpio.h>
> > #endif
> >
> > #define PCA953X_INPUT 0
> > @@ -539,55 +538,6 @@ static void pca953x_irq_teardown(struct pca953x_chip
> > *chip) }
> > #endif
> >
> > -/*
> > - * Handlers for alternative sources of platform_data
> > - */
> > -#ifdef CONFIG_OF_GPIO
> > -/*
> > - * Translate OpenFirmware node properties into platform_data
> > - */
> > -static struct pca953x_platform_data *
> > -pca953x_get_alt_pdata(struct i2c_client *client)
> > -{
> > - struct pca953x_platform_data *pdata;
> > - struct device_node *node;
> > - const __be32 *val;
> > - int size;
> > -
> > - node = client->dev.of_node;
> > - if (node == NULL)
> > - return NULL;
> > -
> > - pdata = kzalloc(sizeof(struct pca953x_platform_data), GFP_KERNEL);
> > - if (pdata == NULL) {
> > - dev_err(&client->dev, "Unable to allocate
> > platform_data\n");
> > - return NULL;
> > - }
> > -
> > - pdata->gpio_base = -1;
> > - val = of_get_property(node, "linux,gpio-base", &size);
> > - if (val) {
> > - if (size != sizeof(*val))
> > - dev_warn(&client->dev, "%s: wrong
> > linux,gpio-base\n",
> > - node->full_name);
> > - else
> > - pdata->gpio_base = be32_to_cpup(val);
> > - }
> > -
> > - val = of_get_property(node, "polarity", NULL);
> > - if (val)
> > - pdata->invert = *val;
> > -
> > - return pdata;
> > -}
> > -#else
> > -static struct pca953x_platform_data *
> > -pca953x_get_alt_pdata(struct i2c_client *client)
> > -{
> > - return NULL;
> > -}
> > -#endif
> > -
>
> Ah, hmm. I missed that you were adding documentation for properties
> that were already implemented. I try really hard not to break things
> that others are already relying on, so I don't think this code can be
> removed. However, bonus points if you make it deprecated and spit
> out a scary warning when these properties are used.
Ok :-)
Is something like a WARN() a good thing to do here?
> > static int __devinit device_pca953x_init(struct pca953x_chip *chip, int
> > invert) {
> > int ret;
> > @@ -654,7 +604,17 @@ static int __devinit pca953x_probe(struct i2c_client
> > *client,
> > pdata = client->dev.platform_data;
> > if (pdata == NULL) {
> > - pdata = pca953x_get_alt_pdata(client);
> > + pdata = kzalloc(sizeof(struct pca953x_platform_data),
> > GFP_KERNEL);
> > + if (pdata == NULL) {
> > + dev_err(&client->dev, "Unable to allocate
> > platform_data\n");
> > + goto out_failed;
> > + }
> > + pdata->gpio_base = -1;
> > +#ifdef CONFIG_OF_GPIO
> > + /* If I2C node has no interrupts property, disable GPIO
> > interrupts */
> > + if (of_find_property(client->dev.of_node, "interrupts",
> > NULL) == NULL)
> > + pdata->irq_base = -1;
> > +#endif
>
> Interesting fact: pdata is only used during setup of this driver. All
> the goofing around to kzalloc a pdata for the dt use case is really
> kind of pointless, and the driver could be simpler if it were removed.
> It would be nice if somebody could investigate this.
I agree. Before I fix that, would it have been ok to just look up the
"interrupts" property like this to decide whether to activate GPIO-interrupt
support?
Unfortunately of_platform code leaves the .irq member as 0 if this property is
not specified, and AFAIK, "0" is a valid IRQ number on some platforms, so I
can't check on the value.
Should I post a complete new patch set, or can I just reply on the not yet
accepted parts (2 and 3, while 6 could be dismissed)?
Also, I just realized that I do need to free the alloc'd irq descriptors in
case the driver fails in gpiochip_add(). You already accepted that patch,
though. Should I post a separate patch adding just the missing
irq_free_descs(), or should I modify the patch and repost it?
Best regards,
--
David Jander
Protonic Holland.
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