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Subject: Re: [PATCH 6/7] media: v4l2-mem2mem: add v4l2_m2m_get_unmapped_area
 for no-mmu platform
To:     dillon.minfei@gmail.com, mchehab@kernel.org,
        mchehab+huawei@kernel.org, ezequiel@collabora.com,
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Cc:     patrice.chotard@foss.st.com, hugues.fruchet@foss.st.com,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
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References: <1621508727-24486-1-git-send-email-dillon.minfei@gmail.com>
 <1621508727-24486-7-git-send-email-dillon.minfei@gmail.com>
From:   Hans Verkuil <hverkuil-cisco@xs4all.nl>
Message-ID: <d9d2a893-a159-1681-866f-e905609ce9d0@xs4all.nl>
Date:   Thu, 17 Jun 2021 11:58:38 +0200
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On 20/05/2021 13:05, dillon.minfei@gmail.com wrote:
> From: Dillon Min <dillon.minfei@gmail.com>
> 
> For platforms without MMU the m2m provides a helper method
> v4l2_m2m_get_unmapped_area(), The mmap() routines will call
> this to get a proposed address for the mapping.
> 
> More detailed information about get_unmapped_area can be found in
> Documentation/nommu-mmap.txt

I'm getting checkpatch.pl --strict warnings:

CHECK: Alignment should match open parenthesis
#31: FILE: drivers/media/v4l2-core/v4l2-mem2mem.c:971:
+unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
+               unsigned long len, unsigned long pgoff, unsigned long flags)

CHECK: Alignment should match open parenthesis
#62: FILE: include/media/v4l2-mem2mem.h:500:
+unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
+               unsigned long len, unsigned long pgoff, unsigned long flags);

Regards,

	Hans

> 
> Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
> ---
>  drivers/media/v4l2-core/v4l2-mem2mem.c | 20 ++++++++++++++++++++
>  include/media/v4l2-mem2mem.h           |  4 ++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
> index e7f4bf5bc8dd..f82a18ecab2f 100644
> --- a/drivers/media/v4l2-core/v4l2-mem2mem.c
> +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
> @@ -966,6 +966,26 @@ int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
>  }
>  EXPORT_SYMBOL(v4l2_m2m_mmap);
>  
> +#ifndef CONFIG_MMU
> +unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
> +		unsigned long len, unsigned long pgoff, unsigned long flags)
> +{
> +	struct v4l2_fh *fh = file->private_data;
> +	unsigned long offset = pgoff << PAGE_SHIFT;
> +	struct vb2_queue *vq;
> +
> +	if (offset < DST_QUEUE_OFF_BASE) {
> +		vq = v4l2_m2m_get_src_vq(fh->m2m_ctx);
> +	} else {
> +		vq = v4l2_m2m_get_dst_vq(fh->m2m_ctx);
> +		pgoff -= (DST_QUEUE_OFF_BASE >> PAGE_SHIFT);
> +	}
> +
> +	return vb2_get_unmapped_area(vq, addr, len, pgoff, flags);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_m2m_get_unmapped_area);
> +#endif
> +
>  #if defined(CONFIG_MEDIA_CONTROLLER)
>  void v4l2_m2m_unregister_media_controller(struct v4l2_m2m_dev *m2m_dev)
>  {
> diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
> index 5a91b548ecc0..91269227c265 100644
> --- a/include/media/v4l2-mem2mem.h
> +++ b/include/media/v4l2-mem2mem.h
> @@ -495,6 +495,10 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
>  int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
>  		  struct vm_area_struct *vma);
>  
> +#ifndef CONFIG_MMU
> +unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
> +		unsigned long len, unsigned long pgoff, unsigned long flags);
> +#endif
>  /**
>   * v4l2_m2m_init() - initialize per-driver m2m data
>   *
>