From: robherring2@gmail•com (Rob Herring)
To: linux-arm-kernel@lists•infradead.org
Subject: Platform data from devicetree
Date: Wed, 08 Aug 2012 18:23:54 -0500 [thread overview]
Message-ID: <5022F50A.3020105@gmail.com> (raw)
In-Reply-To: <1344467186.6707.6.camel@gitbox>
On 08/08/2012 06:06 PM, Tony Prisk wrote:
> Quick question regarding platform_devices created from devicetree.
>
> At the moment, we do a of_match_device() against vt8500_gpio_dt_ids[] to
> get an of_device_id that contains the .data field to pass into the
> driver.
>
> Given that pdev is created from a match against vt8500_gpio_dt_ids[] as
> well, why does pdev->dev.of_node.data == NULL? Is this data not
> populated into this field? What data can be passed into this field?
>
This commit may be why:
commit b1608d69cb804e414d0887140ba08a9398e4e638
Author: Grant Likely <grant.likely@secretlab•ca>
Date: Wed May 18 11:19:24 2011 -0600
drivercore: revert addition of of_match to struct device
Commit b826291c, "drivercore/dt: add a match table pointer to struct
device" added an of_match pointer to struct device to cache the
of_match_table entry discovered at driver match time. This was unsafe
because matching is not an atomic operation with probing a driver. If
two or more drivers are attempted to be matched to a driver at the
same time, then the cached matching entry pointer could get
overwritten.
This patch reverts the of_match cache pointer and reworks all users to
call of_match_device() directly instead.
Signed-off-by: Grant Likely <grant.likely@secretlab•ca>
> Regards
>
> Tony Prisk
>
>
> Example code below:
>
> static struct of_device_id vt8500_gpio_dt_ids[] = {
> { .compatible = "via,vt8500-gpio", .data = &vt8500_data, },
> { .compatible = "wm,wm8505-gpio", .data = &wm8505_data, },
> { .compatible = "wm,wm8650-gpio", .data = &wm8650_data, },
> { /* Sentinel */ },
> };
>
> static int __devinit vt8500_gpio_probe(struct platform_device *pdev)
> {
> void __iomem *gpio_base;
> struct device_node *np;
> const struct of_device_id *of_id =
> of_match_device(vt8500_gpio_dt_ids, &pdev->dev);
>
> if (!of_id) {
> dev_err(&pdev->dev, "Failed to find gpio controller\n");
> return -ENODEV;
> }
>
> np = pdev->dev.of_node;
> ...
> }
>
> static struct platform_driver vt8500_gpio_driver = {
> .probe = vt8500_gpio_probe,
> .driver = {
> .name = "vt8500-gpio",
> .owner = THIS_MODULE,
> .of_match_table = vt8500_gpio_dt_ids,
> },
> };
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
next prev parent reply other threads:[~2012-08-08 23:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-08 23:06 Platform data from devicetree Tony Prisk
2012-08-08 23:23 ` Rob Herring [this message]
2012-08-09 0:35 ` Tony Prisk
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