Re: [PATCH v2 6/6] usb: host: ohci-exynos: Use devm_ioremap_resource instead of devm_ioremap

[Vivek Gautam <gautam.vivek@samsung.com>]

Hi,


On Sat, May 10, 2014 at 5:30 PM, Vivek Gautam <gautam.vivek@samsung.com> wrote:
> Using devm_ioremap_resource() API should actually be preferred over
> devm_ioremap(), since the former request the mem region first and then
> gives back the ioremap'ed memory pointer.
> devm_ioremap_resource() calls request_mem_region(), therby preventing
> other drivers to make any overlapping call to the same region.
>
> Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>

Although this patch and rest in the series are merged.
But i have got a doubt, so making this thread alive.

> ---
>  drivers/usb/host/ohci-exynos.c |    7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/host/ohci-exynos.c b/drivers/usb/host/ohci-exynos.c
> index 9cf80cb..dec691d 100644
> --- a/drivers/usb/host/ohci-exynos.c
> +++ b/drivers/usb/host/ohci-exynos.c
> @@ -120,10 +120,9 @@ skip_phy:
>
>         hcd->rsrc_start = res->start;
>         hcd->rsrc_len = resource_size(res);
> -       hcd->regs = devm_ioremap(&pdev->dev, res->start, hcd->rsrc_len);
> -       if (!hcd->regs) {
> -               dev_err(&pdev->dev, "Failed to remap I/O memory\n");
> -               err = -ENOMEM;
> +       hcd->regs = devm_ioremap_resource(&pdev->dev, res);

Here, we replaced devm_ioremap() call with devm_ioremap_resource(),
which internally
requests the memory region and then does a "devm_ioremap()" or
"devm_ioremap_nocache()"
based on the check for IORESOURCE_CACHEABLE flag.

But this flag is not set for the resource of this device.
So should we be explicitly setting the flag in driver ?

The query goes for other patches too in this series, wherein
devm_ioremap() call is replaced with devm_ioremap_resource().

[snip]


-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India