Re: [PATCH v4 2/4] fbmem: add a default get_fb_unmapped_area function

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Benjamin,

Thank you for the patch.

On Wednesday 07 Dec 2016 11:06:49 Benjamin Gaignard wrote:
> Allow generic frame-buffer to provide a default
> get_fb_unmapped_area function if specific devices need it.
> 
> Usually this function is defined in architecture directories but
> define it here may limit code duplication especially for all ARM
> platforms without MMU.

I still would like to see an explanation why an architecture-specific version 
is sometimes needed, and why this implementation is a reasonable default. 
Furthermore, it looks very similar to the blackfin implementation, so if you 
can't unify the two I'd like to know why.

> version 4:
> - introdude a configuration flag to be independent of architecture
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> ---
>  drivers/video/fbdev/Kconfig      |  8 ++++++++
>  drivers/video/fbdev/core/fbmem.c | 15 +++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> index 5d3b0db..922e4ea 100644
> --- a/drivers/video/fbdev/Kconfig
> +++ b/drivers/video/fbdev/Kconfig
> @@ -138,6 +138,14 @@ config FB_SYS_IMAGEBLIT
>  	  blitting. This is used by drivers that don't provide their own
>  	  (accelerated) version and the framebuffer is in system RAM.
> 
> +config FB_PROVIDE_GET_FB_UNMAPPED_AREA
> +	bool
> +	depends on FB
> +	default n
> +	---help---
> +	  Allow generic frame-buffer to provide get_fb_unmapped_area
> +	  function.
> +
>  menuconfig FB_FOREIGN_ENDIAN
>  	bool "Framebuffer foreign endianness support"
>  	depends on FB
> diff --git a/drivers/video/fbdev/core/fbmem.c
> b/drivers/video/fbdev/core/fbmem.c index 76c1ad9..22321a2 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1492,6 +1492,21 @@ static long fb_compat_ioctl(struct file *file,
> unsigned int cmd, return 0;
>  }
> 
> +#ifdef CONFIG_FB_PROVIDE_GET_FB_UNMAPPED_AREA
> +unsigned long get_fb_unmapped_area(struct file *filp,
> +				   unsigned long addr, unsigned long len,
> +				   unsigned long pgoff, unsigned long flags)
> +{
> +	struct fb_info * const info = filp->private_data;
> +	unsigned long fb_size = PAGE_ALIGN(info->fix.smem_len);
> +
> +	if (pgoff > fb_size || len > fb_size - pgoff)
> +		return -EINVAL;
> +
> +	return (unsigned long)info->screen_base + pgoff;
> +}
> +#endif
> +
>  static const struct file_operations fb_fops = {
>  	.owner =	THIS_MODULE,
>  	.read =		fb_read,

-- 
Regards,

Laurent Pinchart

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