Re: [PATCH 03/11] Bring in dynamic videomode selection at runtime

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, Oct 22, 2010 at 06:53:17PM +0200, Juergen Beisert wrote:
> This patch mostly rewrites all parts of /drivers/video/fb.c. As it changes
> the API to the drivers, it must be done in one step to keep the repository
> bisectable. But to do it in one step makes the patches itself unreadable.
> 
> So, I decided to do it in a few steps, only for the review. All patches marked
> with a "step n of m" should be merged, prior the final commit into the
> repository.
> 
> This step brings in the required functions for dynamic videomode selection at
> runtime, but keep the old functions untouched (the new ones are commented out).
> 
> This is patch 1 of 7 to keep the repository bisectable.
> 
> Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
> ---
>  drivers/video/Kconfig |   23 +++++
>  drivers/video/fb.c    |  251 +++++++++++++++++++++++++++++++++++++++++++++++++
>  include/fb.h          |   40 ++++++++
>  3 files changed, 314 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 7a89a3f..e6ecfc8 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -5,6 +5,29 @@ menuconfig VIDEO
>  
>  if VIDEO
>  
> +comment "runtime options"
> +
> +config VIDEO_DELAY_ENABLING
> +	bool "Delayed enabling"
> +	help
> +	  Say 'y' here to delay enabling video output. This is useful to first
> +	  fill the framebuffer (splash screen for example) prior enabling the
> +	  video device.
> +          This entry adds the "enable" parameter to the video device, to enable
> +	  or disable video output at runtime.
> +
> +config VIDEO_DELAY_INIT
> +	bool "Delayed initialization"
> +	select VIDEO_DELAY_ENABLING
> +	help
> +	  If the platform supports more than one video mode say 'y' her to delay
> +	  the initialization of the video device until any kind of barebox's
> +          shell code sets up the correct mode at runtime.
> +          This entry adds the "mode" parameter to the video device, to setup
> +          the desired videomode prior enabling it at runtime.

I think the framebuffers should *never* be activated by the setup code
and should be explicitely initialized by doing a 'fb0.enable=1' on the
command line. This way we have the most flexibility. We can enable
the framebuffer when we actually need it, we can draw a splash screen
before enabling it so that we do not have a black screen before we draw
an image. Also, the environment can decide to leave the framebuffer
disabled because the kernel will draw another screen a second later. If
necessary, the environemt can do a fb0.display="sharp-whatever" before
activating it. And we do not need any kconfig options for this.

Sascha


> +
> +comment "drivers"
> +
>  config DRIVER_VIDEO_IMX
>  	bool "i.MX framebuffer driver"
>  	depends on ARCH_IMX1 || ARCH_IMX21 || ARCH_IMX25 || ARCH_IMX27
> diff --git a/drivers/video/fb.c b/drivers/video/fb.c
> index f9a425e..c2934f6 100644
> --- a/drivers/video/fb.c
> +++ b/drivers/video/fb.c
> @@ -1,3 +1,4 @@
> +#include <init.h>
>  #include <common.h>
>  #include <fb.h>
>  #include <errno.h>
> @@ -5,6 +6,8 @@
>  #include <getopt.h>
>  #include <fcntl.h>
>  #include <fs.h>
> +#include <malloc.h>
> +#include <xfuncs.h>
>  
>  static int fb_ioctl(struct cdev* cdev, int req, void *data)
>  {
> @@ -57,6 +60,141 @@ static int fb_enable_set(struct device_d *dev, struct param_d *param,
>  	return 0;
>  }
>  
> +#if 0
> +#ifdef CONFIG_VIDEO_DELAY_INIT
> +static int fb_check_if_already_initialized(struct device_d *fb_dev)
> +{
> +	struct cdev *cdev = fb_dev->priv;
> +	struct fb_info *info = cdev->priv;
> +
> +	if (info->active_mode != NULL) {
> +		pr_err("Video mode '%s' is already set. Cannot change colour depth anymore.\n", info->active_mode->name);
> +		return -EPERM;
> +	}
> +
> +	return 0;
> +}
> +
> +static int fb_cdepth_set(struct device_d *fb_dev, struct param_d *param, const char *val)
> +{
> +	struct cdev *cdev = fb_dev->priv;
> +	struct fb_info *info = cdev->priv;
> +	unsigned cdepth;
> +	int rc;
> +
> +	rc = fb_check_if_already_initialized(fb_dev);
> +	if (rc != 0)
> +		return rc;
> +
> +	cdepth = simple_strtoul(val, NULL, 0);
> +	if (cdepth != 0)
> +		info->bits_per_pixel = cdepth;
> +	else
> +		return -EINVAL;
> +
> +	return dev_param_set_generic(fb_dev, param, val);
> +}
> +#endif
> +
> +#ifdef CONFIG_VIDEO_DELAY_ENABLING
> +static int fb_enable_set(struct device_d *fb_dev, struct param_d *param, const char *val)
> +{
> +	struct cdev *cdev = fb_dev->priv;
> +	struct fb_info *info = cdev->priv;
> +	struct fb_host *host = fb_dev->platform_data;
> +	int enable;
> +	char *new;
> +
> +	if (!val)
> +		return dev_param_set_generic(fb_dev, param, NULL);
> +
> +	enable = simple_strtoul(val, NULL, 0);
> +
> +	if (info->enabled == !!enable)
> +		return 0;
> +
> +	if (enable) {
> +		(host->fb_enable)(info);
> +		new = "1";
> +	} else {
> +		(host->fb_disable)(info);
> +		new = "0";
> +	}
> +
> +	info->enabled = !!enable;
> +
> +	return dev_param_set_generic(fb_dev, param, new);
> +}
> +#endif
> +
> +static void fb_list_modes(struct fb_host *host)
> +{
> +	unsigned u;
> +
> +	if (host->mode_cnt == 0)
> +		return;
> +
> +	printf(" Supported video mode(s):\n");
> +	for (u = 0; u < host->mode_cnt; u++)
> +		printf("  '%s'\n", host->mode[u].name);
> +}
> +
> +static int fb_activate_mode(struct device_d *fb_dev, const struct fb_videomode *mode)
> +{
> +	struct cdev *cdev = fb_dev->priv;
> +	struct fb_info *info = cdev->priv;
> +	struct fb_host *host = fb_dev->platform_data;
> +	int rc;
> +
> +	rc = (host->fb_mode)(info, mode);
> +	if (rc != 0)
> +		return rc;
> +
> +	info->active_mode = mode;
> +	/*
> +	 * At this point of time we know the remaining information we need
> +	 * for the cdev and fb_info structure.
> +	 */
> +	cdev->size = fb_dev->size;
> +	info->xres = mode->xres;
> +	info->yres = mode->yres;
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_VIDEO_DELAY_INIT
> +static int fb_mode_set(struct device_d *fb_dev, struct param_d *param, const char *name)
> +{
> +	struct fb_host *host = fb_dev->platform_data;
> +	unsigned u;
> +	int rc;
> +
> +	pr_debug("%s called\n", __func__);
> +
> +	rc = fb_check_if_already_initialized(fb_dev);
> +	if (rc != 0)
> +		return rc;
> +
> +	/* Search for the requested video mode by name */
> +	for (u = 0; u < host->mode_cnt; u++) {
> +		if (!strcmp(host->mode[u].name, name))
> +			break;
> +	}
> +	if (u >= host->mode_cnt) {
> +		fb_list_modes(host);	/* no mode with 'name' found */
> +		return -ENODEV;
> +	} else {
> +		rc = fb_activate_mode(fb_dev, &host->mode[u]);
> +	}
> +
> +	if (rc == 0)
> +		dev_param_set_generic(fb_dev, param, name);
> +
> +	return rc;
> +}
> +#endif
> +#endif
> +
>  static struct file_operations fb_ops = {
>  	.read	= mem_read,
>  	.write	= mem_write,
> @@ -65,6 +203,119 @@ static struct file_operations fb_ops = {
>  	.ioctl	= fb_ioctl,
>  };
>  
> +#if 0
> +static int add_fb_parameter(struct device_d *fb_dev)
> +{
> +#ifdef CONFIG_VIDEO_DELAY_INIT
> +	struct cdev *cdev = fb_dev->priv;
> +	struct fb_info *info = cdev->priv;
> +	char cd[10];
> +
> +	/** @todo provide base address parameter for the user */
> +
> +	dev_add_param(fb_dev, "cdepth", fb_cdepth_set, NULL, 0);
> +	if (info->bits_per_pixel == 0) {
> +		dev_set_param(fb_dev, "cdepth", "16");
> +		info->bits_per_pixel = 16;
> +	} else {
> +		sprintf(cd, "%u", info->bits_per_pixel);
> +		dev_set_param(fb_dev, "cdepth", cd);
> +	}
> +	dev_add_param(fb_dev, "mode", fb_mode_set, NULL, 0);
> +	/* default is 'none' for delayed video mode setup */
> +#endif
> +#ifdef CONFIG_VIDEO_DELAY_ENABLING
> +	dev_add_param(fb_dev, "enable", fb_enable_set, NULL, 0);
> +	/* default is 'off' for delayed video output */
> +#endif
> +	return 0;
> +}
> +
> +struct framebuffer_desc {
> +	struct cdev cdev;
> +	struct fb_info info;
> +};
> +
> +static int fb_probe(struct device_d *fb_dev)
> +{
> +	int id = get_free_deviceid("fb");
> +	struct cdev *cdev;
> +	struct fb_info *info;
> +	struct fb_host *host = fb_dev->platform_data;
> +
> +	cdev = xzalloc(sizeof(struct framebuffer_desc));
> +	info = (struct fb_info*)&cdev[1];
> +
> +	fb_dev->priv = cdev;	/* pointer forward */
> +	cdev->dev = fb_dev;	/* pointer backward */
> +
> +	cdev->ops = &fb_ops;
> +	cdev->name = asprintf("fb%d", id);
> +
> +	cdev->size = fb_dev->size;	/* use the default if any */
> +	cdev->priv = info;
> +
> +	info->host = host;
> +	info->fb_dev = fb_dev;
> +
> +	/* setup defaults */
> +	if (host->bits_per_pixel != 0)
> +		info->bits_per_pixel = host->bits_per_pixel;
> +	else
> +		info->bits_per_pixel = 16;	/* means RGB565 */
> +
> +	/* add params on demand */
> +	add_fb_parameter(fb_dev);
> +
> +	devfs_create(cdev);
> +#ifndef CONFIG_VIDEO_DELAY_INIT
> +	/* initialize video mode immediately (the first one) */
> +	fb_activate_mode(fb_dev, &host->mode[0]);
> +#endif
> +#ifndef CONFIG_VIDEO_DELAY_ENABLING
> +	/* enable video output immediately */
> +	(host->fb_enable)(info);
> +#endif
> +	return 0;
> +}
> +
> +static struct driver_d fb_driver = {
> +	.name	= "framebuffer",
> +	.probe	= fb_probe,
> +};
> +
> +static int framebuffer_init(void)
> +{
> +	return register_driver(&fb_driver);
> +}
> +
> +device_initcall(framebuffer_init);
> +
> +struct device_d *register_framebuffer(struct fb_host *host, void *base, unsigned size)
> +{
> +	struct device_d *fb_dev;
> +	int rc;
> +
> +	fb_dev = xzalloc(sizeof(struct device_d));
> +
> +	strcpy(fb_dev->name, fb_driver.name);
> +	fb_dev->platform_data = (void*)host;
> +
> +	/* setup the defaults for this framebuffer if given */
> +	fb_dev->size = size;
> +	fb_dev->map_base = (unsigned long)base;
> +
> +	rc = register_device(fb_dev);
> +	if (rc != 0) {
> +		pr_debug("Cannot register framebuffer device\n");
> +		free(fb_dev);
> +		return NULL;
> +	}
> +
> +	return fb_dev;
> +}
> +#endif
> +
>  int register_framebuffer(struct fb_info *info)
>  {
>  	int id = get_free_deviceid("fb");
> diff --git a/include/fb.h b/include/fb.h
> index 218b244..96edc24 100644
> --- a/include/fb.h
> +++ b/include/fb.h
> @@ -85,6 +85,46 @@ struct fb_ops {
>  	void (*fb_disable)(struct fb_info *info);
>  };
>  
> +#if 0
> +struct fb_host {
> +	const struct fb_videomode *mode;
> +	unsigned mode_cnt;
> +
> +	struct device_d *hw_dev;
> +
> +	/* callbacks into the video hardware driver */
> +	int (*fb_setcolreg)(struct fb_info*, unsigned, unsigned, unsigned, unsigned, unsigned);
> +	int (*fb_mode)(struct fb_info*, const struct fb_videomode*);
> +	void (*fb_enable)(struct fb_info*);
> +	void (*fb_disable)(struct fb_info*);
> +
> +	unsigned bits_per_pixel;
> +};
> +
> +struct fb_info {
> +	struct fb_host *host;
> +	struct device_d *fb_dev;
> +	const struct fb_videomode *active_mode;
> +
> +	u32 xres;			/* visible resolution		*/
> +	u32 yres;
> +	u32 bits_per_pixel;		/* guess what			*/
> +
> +	u32 grayscale;			/* != 0 Graylevels instead of colors */
> +
> +	struct fb_bitfield red;		/* bitfield in fb mem if true color, */
> +	struct fb_bitfield green;	/* else only length is significant */
> +	struct fb_bitfield blue;
> +	struct fb_bitfield transp;	/* transparency			*/
> +
> +#ifdef CONFIG_VIDEO_DELAY_ENABLING
> +	int enabled;
> +#endif
> +};
> +
> +struct device_d *register_framebuffer(struct fb_host*, void*, unsigned);
> +#endif
> +
>  struct fb_info {
>  	struct fb_videomode *mode;
>  
> -- 
> 1.7.2.3
> 
> 
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