Re: [PATCH 01/28] drm: Polish fbdev helper struct docs

From: Thierry Reding <thierry.reding@gmail.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 01/28] drm: Polish fbdev helper struct docs
Date: Mon, 7 Dec 2015 11:45:22 +0100	[thread overview]
Message-ID: <20151207104522.GD13177@ulmo> (raw)
In-Reply-To: <1449218769-16577-2-git-send-email-daniel.vetter@ffwll.ch>

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On Fri, Dec 04, 2015 at 09:45:42AM +0100, Daniel Vetter wrote:
> Mostly this is just adding extensive docs for the callbacks, but also
> a few other additions.
> 
> v2: Use FIXME comments to annotate helper hooks that should be
> replaced.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  include/drm/drm_fb_helper.h | 92 ++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 79 insertions(+), 13 deletions(-)
> 
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 87b090c4b730..5ce033e36039 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -74,25 +74,76 @@ struct drm_fb_helper_surface_size {
>  
>  /**
>   * struct drm_fb_helper_funcs - driver callbacks for the fbdev emulation library
> - * @gamma_set: Set the given gamma lut register on the given crtc.
> - * @gamma_get: Read the given gamma lut register on the given crtc, used to
> - *             save the current lut when force-restoring the fbdev for e.g.
> - *             kdbg.
> - * @fb_probe: Driver callback to allocate and initialize the fbdev info
> - *            structure. Furthermore it also needs to allocate the drm
> - *            framebuffer used to back the fbdev.
> - * @initial_config: Setup an initial fbdev display configuration
>   *
>   * Driver callbacks used by the fbdev emulation helper library.
>   */
>  struct drm_fb_helper_funcs {
> +	/**
> +	 * @gamma_set:
> +	 *
> +	 * Set the given gamma lut register on the given crtc.
> +	 *
> +	 * This callback is optional.
> +	 *
> +	 * FIXME:
> +	 *
> +	 * This callback is functionally redundant with the core gamma table
> +	 * support and simply exists because the fbdev hasn't yet been
> +	 * refactored to use the core gamma table interfaces.
> +	 */
>  	void (*gamma_set)(struct drm_crtc *crtc, u16 red, u16 green,
>  			  u16 blue, int regno);

Pardon my ignorance, but is there a way to document parameters with this
new syntax?

> +	/**
> +	 * @gamma_get:
> +	 *
> +	 * Read the given gamma lut register on the given crtc, used to save the
> +	 * current lut when force-restoring the fbdev for e.g. kdbg.
> +	 *
> +	 * This callback is optional.
> +	 *
> +	 * FIXME:
> +	 *
> +	 * This callback is functionally redundant with the core gamma table
> +	 * support and simply exists because the fbdev hasn't yet been
> +	 * refactored to use the core gamma table interfaces.
> +	 */
>  	void (*gamma_get)(struct drm_crtc *crtc, u16 *red, u16 *green,
>  			  u16 *blue, int regno);

Nit: While at it, perhaps (here and in the @gamma_set documentation):
s/lut/LUT/ and s/crtc/CRTC/?

>  
> +	/**
> +	 * @fb_probe:
> +	 *
> +	 * Driver callback to allocate and initialize the fbdev info structure.
> +	 * Furthermore it also needs to allocate the drm framebuffer used to
> +	 * back the fbdev.
> +	 *
> +	 * This callback is mandatory.
> +	 *
> +	 * RETURNS:
> +	 *
> +	 * The driver should return 0 on success and a negative error code on
> +	 * failure.
> +	 */
>  	int (*fb_probe)(struct drm_fb_helper *helper,
>  			struct drm_fb_helper_surface_size *sizes);

Nit: s/drm/DRM/

>  /**
> - * struct drm_fb_helper - helper to emulate fbdev on top of kms
> + * struct drm_fb_helper - main structure to emulate fbdev on top of kms

s/kms/KMS

>   * @fb:  Scanout framebuffer object
>   * @dev:  DRM device

There seems to be an extra space between the : and the description. That
was already there, but maybe worth a follow-up.

>   * @crtc_count: number of possible CRTCs
>   * @crtc_info: per-CRTC helper state (mode, x/y offset, etc)
>   * @connector_count: number of connected connectors
>   * @connector_info_alloc_count: size of connector_info
> + * @connector_info: array of per-connector information
>   * @funcs: driver callbacks for fb helper
>   * @fbdev: emulated fbdev device info struct
>   * @pseudo_palette: fake palette of 16 colors
> - * @kernel_fb_list: list_head in kernel_fb_helper_list
> - * @delayed_hotplug: was there a hotplug while kms master active?
> + *
> + * This is the main structure used by the fbdev helpers. Drivers supporting
> + * fbdev emulation should embedded this into their overall driver structure.
> + * Drivers must also fill out a struct &drm_fb_helper_funcs with a few
> + * operations.
>   */
>  struct drm_fb_helper {
>  	struct drm_framebuffer *fb;
> @@ -129,10 +184,21 @@ struct drm_fb_helper {
>  	const struct drm_fb_helper_funcs *funcs;
>  	struct fb_info *fbdev;
>  	u32 pseudo_palette[17];
> +
> +	/**
> +	 * @kernel_fb_list:
> +	 *
> +	 * Entry on the global kernel_fb_helper_list, used for kgdb entry/exit.
> +	 */
>  	struct list_head kernel_fb_list;
>  
> -	/* we got a hotplug but fbdev wasn't running the console
> -	   delay until next set_par */
> +	/**
> +	 * @delayed_hotplug:
> +	 *
> +	 * A hotplug was received while fbdev wasn't in control of the drm
> +	 * device, i.e. another kms master was active. The output configuration
> +	 * needs to be reprobe when fbdev is in control again.

s/drm/DRM/, s/kms/KMS/

Otherwise looks really good.

Thierry

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