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Date: Mon, 30 Nov 2015 15:07:35 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc: linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Russell King - ARM Linux <linux@....linux.org.uk>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Kukjin Kim <kgene@...nel.org>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v2 3/4] ARM: amba: Move reading of periphid to amba_match()
On 26 November 2015 at 13:49, Marek Szyprowski <m.szyprowski@...sung.com> wrote:
> From: Tomeu Vizoso <tomeu.vizoso@...labora.com>
>
> Reading the periphid when the Primecell device is registered means that
> the apb pclk must be available by then or the device won't be registered
> at all.
>
> By reading the periphid in amba_match() we can return -EPROBE_DEFER if
> the apb pclk isn't there yet and the device will be retried later.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
> drivers/amba/bus.c | 88 ++++++++++++++++++++++++++++--------------------------
> 1 file changed, 46 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index f009936..72ebf9b 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -24,6 +24,8 @@
>
> #define to_amba_driver(d) container_of(d, struct amba_driver, drv)
>
> +static int read_periphid(struct amba_device *d, unsigned int *periphid);
I would change this to:
static int amba_read_periphid(struct amba_device *dev);
That will actually also make the patch smaller.
> +
> static const struct amba_id *
> amba_lookup(const struct amba_id *table, struct amba_device *dev)
> {
> @@ -43,11 +45,22 @@ static int amba_match(struct device *dev, struct device_driver *drv)
> {
> struct amba_device *pcdev = to_amba_device(dev);
> struct amba_driver *pcdrv = to_amba_driver(drv);
> + int ret;
>
> /* When driver_override is set, only bind to the matching driver */
> if (pcdev->driver_override)
> return !strcmp(pcdev->driver_override, drv->name);
>
> + if (!pcdev->periphid) {
> + ret = read_periphid(pcdev, &pcdev->periphid);
> + if (ret) {
> + if (ret != -EPROBE_DEFER)
> + dev_err(dev, "Failed to read periphid: %d",
> + ret);
> + return ret;
> + }
> + }
> +
> return amba_lookup(pcdrv->id_table, pcdev) != NULL;
> }
>
> @@ -336,44 +349,22 @@ static void amba_device_release(struct device *dev)
> kfree(d);
> }
>
> -/**
> - * amba_device_add - add a previously allocated AMBA device structure
> - * @dev: AMBA device allocated by amba_device_alloc
> - * @parent: resource parent for this devices resources
> - *
> - * Claim the resource, and read the device cell ID if not already
> - * initialized. Register the AMBA device with the Linux device
> - * manager.
> - */
> -int amba_device_add(struct amba_device *dev, struct resource *parent)
> +static int read_periphid(struct amba_device *d, unsigned int *periphid)
> {
> u32 size;
> void __iomem *tmp;
> - int i, ret;
> -
> - WARN_ON(dev->irq[0] == (unsigned int)-1);
> - WARN_ON(dev->irq[1] == (unsigned int)-1);
> -
> - ret = request_resource(parent, &dev->res);
> - if (ret)
> - goto err_out;
> -
> - /* Hard-coded primecell ID instead of plug-n-play */
This line now belongs in amba_match(), please move it there instead of
just deleting it.
> - if (dev->periphid != 0)
> - goto skip_probe;
> + int i, ret = 0;
>
> /*
> * Dynamically calculate the size of the resource
> * and use this for iomap
> */
> - size = resource_size(&dev->res);
> - tmp = ioremap(dev->res.start, size);
> - if (!tmp) {
> - ret = -ENOMEM;
> - goto err_release;
> - }
> + size = resource_size(&d->res);
> + tmp = ioremap(d->res.start, size);
> + if (!tmp)
> + return -ENOMEM;
>
> - ret = amba_get_enable_pclk(dev);
> + ret = amba_get_enable_pclk(d);
> if (ret == 0) {
> u32 pid, cid;
>
> @@ -388,37 +379,50 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
> cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
> (i * 8);
>
> - amba_put_disable_pclk(dev);
> + amba_put_disable_pclk(d);
>
> if (cid == AMBA_CID || cid == CORESIGHT_CID)
> - dev->periphid = pid;
> + *periphid = pid;
>
> - if (!dev->periphid)
> + if (!*periphid)
> ret = -ENODEV;
> }
>
> iounmap(tmp);
>
> + return ret;
> +}
> +
> +/**
> + * amba_device_add - add a previously allocated AMBA device structure
> + * @dev: AMBA device allocated by amba_device_alloc
> + * @parent: resource parent for this devices resources
> + *
> + * Claim the resource, and register the AMBA device with the Linux device
> + * manager.
> + */
> +int amba_device_add(struct amba_device *dev, struct resource *parent)
> +{
> + int ret;
> +
> + WARN_ON(dev->irq[0] == (unsigned int)-1);
> + WARN_ON(dev->irq[1] == (unsigned int)-1);
> +
> + ret = request_resource(parent, &dev->res);
> if (ret)
> - goto err_release;
> + return ret;
>
> - skip_probe:
> ret = device_add(&dev->dev);
> if (ret)
> - goto err_release;
> + return ret;
>
> if (dev->irq[0])
> ret = device_create_file(&dev->dev, &dev_attr_irq0);
> if (ret == 0 && dev->irq[1])
> ret = device_create_file(&dev->dev, &dev_attr_irq1);
> - if (ret == 0)
> - return ret;
> -
> - device_unregister(&dev->dev);
> + if (ret)
> + device_unregister(&dev->dev);
>
> - err_release:
> - release_resource(&dev->res);
> - err_out:
> return ret;
> }
> EXPORT_SYMBOL_GPL(amba_device_add);
> --
> 1.9.2
>
Kind regards
Uffe
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