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Date: Tue, 1 Dec 2015 15:46:24 +0000
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: linux-samsung-soc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Ulf Hansson <ulf.hansson@...aro.org>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>,
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 v3 2/3] ARM: amba: Move reading of periphid to
amba_match()
On Tue, Dec 01, 2015 at 02:34:25PM +0100, Marek Szyprowski 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>
> [minor code adjustments, added missing comment]
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
> drivers/amba/bus.c | 77 +++++++++++++++++++++++++++++-------------------------
> 1 file changed, 41 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index f009936..879a421 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 amba_read_periphid(struct amba_device *dev);
> +
Please avoid forward declarations where possible.
> static const struct amba_id *
> amba_lookup(const struct amba_id *table, struct amba_device *dev)
> {
> @@ -43,11 +45,23 @@ 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);
>
> + /* Do plug-n-play if no hard-coded primecell ID has been provided */
> + if (!pcdev->periphid) {
> + ret = amba_read_periphid(pcdev);
> + 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;
> }
>
> @@ -336,31 +350,11 @@ 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 amba_read_periphid(struct amba_device *dev)
> {
> 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 */
> - if (dev->periphid != 0)
> - goto skip_probe;
> + int i, ret = 0;
>
> /*
> * Dynamically calculate the size of the resource
> @@ -368,10 +362,8 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
> */
> size = resource_size(&dev->res);
> tmp = ioremap(dev->res.start, size);
> - if (!tmp) {
> - ret = -ENOMEM;
> - goto err_release;
> - }
> + if (!tmp)
> + return -ENOMEM;
>
> ret = amba_get_enable_pclk(dev);
> if (ret == 0) {
> @@ -399,26 +391,39 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
>
> 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;
NAK.
The original code handled error conditions correctly. This new code
completely breaks the error handling here by removing the release of
the above requested resource.
--
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according to speedtest.net.
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