Re: [PATCH 03/25] drm/fb_helper: Create wrappers for fb_sys_read/write funcs

From: Daniel Vetter <daniel@ffwll.ch>
To: Archit Taneja <architt@codeaurora.org>
Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 03/25] drm/fb_helper: Create wrappers for fb_sys_read/write funcs
Date: Mon, 13 Jul 2015 09:31:15 +0200	[thread overview]
Message-ID: <20150713073115.GM3736@phenom.ffwll.local> (raw)
In-Reply-To: <1436769501-4105-4-git-send-email-architt@codeaurora.org>

On Mon, Jul 13, 2015 at 12:07:59PM +0530, Archit Taneja wrote:
> Some drm drivers populate their fb_ops with fb_sys_read/write fb sysfs
> ops.
> 
> Create a drm_fb_helper function  that wraps around these calls.
> 
> This is part of an effort to prevent drm drivers from calling fbdev
> functions directly, in order to make fbdev emulation a top level drm
> option.
> 
> Signed-off-by: Archit Taneja <architt@codeaurora.org>
> ---
>  drivers/gpu/drm/Kconfig         |  1 +
>  drivers/gpu/drm/drm_fb_helper.c | 20 ++++++++++++++++++++
>  include/drm/drm_fb_helper.h     |  5 +++++
>  3 files changed, 26 insertions(+)
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index a66ac44..b284cdc 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -37,6 +37,7 @@ config DRM_KMS_FB_HELPER
>  	select FB
>  	select FRAMEBUFFER_CONSOLE if !EXPERT
>  	select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY if FRAMEBUFFER_CONSOLE
> +	select FB_SYS_FOPS
>  	help
>  	  FBDEV helpers for KMS drivers.
>  
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 742377d..795547e 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -744,6 +744,26 @@ void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
>  }
>  EXPORT_SYMBOL(drm_fb_helper_unlink_fbi);
>  
> +ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
> +			size_t count, loff_t *ppos)
> +{
> +	if (info)

I think this check here can never fail (if there's no fbdev you can't call
this function), I don't think we need it. Even for drivers which call this
themselves (like qxl/udl) they only call it from fbdev code.
-Daniel

> +		return fb_sys_read(info, buf, count, ppos);
> +
> +	return -ENODEV;
> +}
> +EXPORT_SYMBOL(drm_fb_helper_sys_read);
> +
> +ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
> +			size_t count, loff_t *ppos)
> +{
> +	if (info)
> +		return fb_sys_write(info, buf, count, ppos);
> +
> +	return -ENODEV;
> +}
> +EXPORT_SYMBOL(drm_fb_helper_sys_write);
> +
>  static int setcolreg(struct drm_crtc *crtc, u16 red, u16 green,
>  		     u16 blue, u16 regno, struct fb_info *info)
>  {
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 4c90837..f74e59e 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -147,6 +147,11 @@ void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
>  
>  void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper);
>  
> +ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
> +			size_t count, loff_t *ppos);
> +ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
> +			size_t count, loff_t *ppos);
> +
>  int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
>  
>  int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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