[v3,1/6] drm/modes: Rewrite the command line parser

From: Maxime Ripard <maxime.ripard@free-electrons.com>

Rewrite the command line parser in order to get away from the state machine
parsing the video mode lines.

Hopefully, this will allow to extend it more easily to support named modes
and / or properties set directly on the command line.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
 drivers/gpu/drm/drm_modes.c | 305 +++++++++++++++++++++++--------------
 1 file changed, 190 insertions(+), 115 deletions(-)

Den 18.04.2019 14.41, skrev Maxime Ripard:
> From: Maxime Ripard <maxime.ripard@free-electrons.com>
> 
> Rewrite the command line parser in order to get away from the state machine
> parsing the video mode lines.
> 
> Hopefully, this will allow to extend it more easily to support named modes
> and / or properties set directly on the command line.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> ---
>  drivers/gpu/drm/drm_modes.c | 305 +++++++++++++++++++++++--------------
>  1 file changed, 190 insertions(+), 115 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index 56f92a0bba62..3f89198f0891 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -30,6 +30,7 @@
>   * authorization from the copyright holder(s) and author(s).
>   */
>  
> +#include <linux/ctype.h>
>  #include <linux/list.h>
>  #include <linux/list_sort.h>
>  #include <linux/export.h>
> @@ -1405,6 +1406,131 @@ void drm_connector_list_update(struct drm_connector *connector)
>  }
>  EXPORT_SYMBOL(drm_connector_list_update);
>  
> +static int drm_mode_parse_cmdline_bpp(const char *str, char **end_ptr,
> +				      struct drm_cmdline_mode *mode)
> +{
> +	if (str[0] != '-')
> +		return -EINVAL;
> +
> +	mode->bpp = simple_strtol(str + 1, end_ptr, 10);

What happens if this is not a number? I didn't find a test for that in
your unit tests. The same goes for _refresh().

> +	mode->bpp_specified = true;
> +
> +	return 0;
> +}
> +
> +static int drm_mode_parse_cmdline_refresh(const char *str, char **end_ptr,
> +					  struct drm_cmdline_mode *mode)
> +{
> +	if (str[0] != '@')
> +		return -EINVAL;
> +
> +	mode->refresh = simple_strtol(str + 1, end_ptr, 10);
> +	mode->refresh_specified = true;
> +
> +	return 0;
> +}
> +
> +static int drm_mode_parse_cmdline_extra(const char *str, int length,
> +					struct drm_connector *connector,
> +					struct drm_cmdline_mode *mode)
> +{
> +	int i;
> +
> +	for (i = 0; i < length; i++) {
> +		switch (str[i]) {
> +		case 'i':
> +			mode->interlace = true;
> +			break;
> +		case 'm':
> +			mode->margins = true;
> +			break;
> +		case 'D':
> +			if (mode->force != DRM_FORCE_UNSPECIFIED)
> +				return -EINVAL;
> +
> +			if ((connector->connector_type != DRM_MODE_CONNECTOR_DVII) &&
> +			    (connector->connector_type != DRM_MODE_CONNECTOR_HDMIB))
> +				mode->force = DRM_FORCE_ON;
> +			else
> +				mode->force = DRM_FORCE_ON_DIGITAL;
> +			break;
> +		case 'd':
> +			if (mode->force != DRM_FORCE_UNSPECIFIED)
> +				return -EINVAL;
> +
> +			mode->force = DRM_FORCE_OFF;
> +			break;
> +		case 'e':
> +			if (mode->force != DRM_FORCE_UNSPECIFIED)
> +				return -EINVAL;
> +
> +			mode->force = DRM_FORCE_ON;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_mode_parse_cmdline_res_mode(const char *str, unsigned int length,
> +					   bool extras,
> +					   struct drm_connector *connector,
> +					   struct drm_cmdline_mode *mode)
> +{
> +	bool rb = false, cvt = false;
> +	int xres = 0, yres = 0;
> +	int remaining, i;
> +	char *end_ptr;
> +
> +	xres = simple_strtol(str, &end_ptr, 10);
> +
> +	if (end_ptr[0] != 'x')

'x600' looks to be a valid resolution here, so I think:
	if (str == end_ptr || end_ptr[0] != 'x')

> +		return -EINVAL;
> +	end_ptr++;
> +
> +	yres = simple_strtol(end_ptr, &end_ptr, 10);
> +
> +	remaining = length - (end_ptr - str);
> +	if (remaining < 0)
> +		return -EINVAL;

Maybe some unit tests: '1024xy' and '1024x', to verify that this does
indeed require a number for yres.

Noralf.

> +
> +	for (i = 0; i < remaining; i++) {
> +		switch (end_ptr[i]) {
> +		case 'M':
> +			cvt = true;
> +			break;
> +		case 'R':
> +			rb = true;
> +			break;
> +		default:
> +			/*
> +			 * Try to pass that to our extras parsing
> +			 * function to handle the case where the
> +			 * extras are directly after the resolution
> +			 */
> +			if (extras) {
> +				int ret = drm_mode_parse_cmdline_extra(end_ptr + i,
> +								       1,
> +								       connector,
> +								       mode);
> +				if (ret)
> +					return ret;
> +			} else {
> +				return -EINVAL;
> +			}
> +		}
> +	}
> +
> +	mode->xres = xres;
> +	mode->yres = yres;
> +	mode->cvt = cvt;
> +	mode->rb = rb;
> +
> +	return 0;
> +}
> +
>  /**
>   * drm_mode_parse_command_line_for_connector - parse command line modeline for connector
>   * @mode_option: optional per connector mode option
> @@ -1431,13 +1557,12 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
>  					       struct drm_cmdline_mode *mode)
>  {
>  	const char *name;
> -	unsigned int namelen;
> -	bool res_specified = false, bpp_specified = false, refresh_specified = false;
> -	unsigned int xres = 0, yres = 0, bpp = 32, refresh = 0;
> -	bool yres_specified = false, cvt = false, rb = false;
> -	bool interlace = false, margins = false, was_digit = false;
> -	int i;
> -	enum drm_connector_force force = DRM_FORCE_UNSPECIFIED;
> +	bool parse_extras = false;
> +	unsigned int bpp_off = 0, refresh_off = 0;
> +	unsigned int mode_end = 0;
> +	char *bpp_ptr = NULL, *refresh_ptr = NULL, *extra_ptr = NULL;
> +	char *bpp_end_ptr = NULL, *refresh_end_ptr = NULL;
> +	int ret;
>  
>  #ifdef CONFIG_FB
>  	if (!mode_option)
> @@ -1450,127 +1575,77 @@ bool drm_mode_parse_command_line_for_connector(const char *mode_option,
>  	}
>  
>  	name = mode_option;
> -	namelen = strlen(name);
> -	for (i = namelen-1; i >= 0; i--) {
> -		switch (name[i]) {
> -		case '@':
> -			if (!refresh_specified && !bpp_specified &&
> -			    !yres_specified && !cvt && !rb && was_digit) {
> -				refresh = simple_strtol(&name[i+1], NULL, 10);
> -				refresh_specified = true;
> -				was_digit = false;
> -			} else
> -				goto done;
> -			break;
> -		case '-':
> -			if (!bpp_specified && !yres_specified && !cvt &&
> -			    !rb && was_digit) {
> -				bpp = simple_strtol(&name[i+1], NULL, 10);
> -				bpp_specified = true;
> -				was_digit = false;
> -			} else
> -				goto done;
> -			break;
> -		case 'x':
> -			if (!yres_specified && was_digit) {
> -				yres = simple_strtol(&name[i+1], NULL, 10);
> -				yres_specified = true;
> -				was_digit = false;
> -			} else
> -				goto done;
> -			break;
> -		case '0' ... '9':
> -			was_digit = true;
> -			break;
> -		case 'M':
> -			if (yres_specified || cvt || was_digit)
> -				goto done;
> -			cvt = true;
> -			break;
> -		case 'R':
> -			if (yres_specified || cvt || rb || was_digit)
> -				goto done;
> -			rb = true;
> -			break;
> -		case 'm':
> -			if (cvt || yres_specified || was_digit)
> -				goto done;
> -			margins = true;
> -			break;
> -		case 'i':
> -			if (cvt || yres_specified || was_digit)
> -				goto done;
> -			interlace = true;
> -			break;
> -		case 'e':
> -			if (yres_specified || bpp_specified || refresh_specified ||
> -			    was_digit || (force != DRM_FORCE_UNSPECIFIED))
> -				goto done;
>  
> -			force = DRM_FORCE_ON;
> -			break;
> -		case 'D':
> -			if (yres_specified || bpp_specified || refresh_specified ||
> -			    was_digit || (force != DRM_FORCE_UNSPECIFIED))
> -				goto done;
> +	if (!isdigit(name[0]))
> +		return false;
>  
> -			if ((connector->connector_type != DRM_MODE_CONNECTOR_DVII) &&
> -			    (connector->connector_type != DRM_MODE_CONNECTOR_HDMIB))
> -				force = DRM_FORCE_ON;
> -			else
> -				force = DRM_FORCE_ON_DIGITAL;
> -			break;
> -		case 'd':
> -			if (yres_specified || bpp_specified || refresh_specified ||
> -			    was_digit || (force != DRM_FORCE_UNSPECIFIED))
> -				goto done;
> +	/* Try to locate the bpp and refresh specifiers, if any */
> +	bpp_ptr = strchr(name, '-');
> +	if (bpp_ptr) {
> +		bpp_off = bpp_ptr - name;
> +		mode->bpp_specified = true;
> +	}
>  
> -			force = DRM_FORCE_OFF;
> -			break;
> -		default:
> -			goto done;
> -		}
> +	refresh_ptr = strchr(name, '@');
> +	if (refresh_ptr) {
> +		refresh_off = refresh_ptr - name;
> +		mode->refresh_specified = true;
>  	}
>  
> -	if (i < 0 && yres_specified) {
> -		char *ch;
> -		xres = simple_strtol(name, &ch, 10);
> -		if ((ch != NULL) && (*ch == 'x'))
> -			res_specified = true;
> -		else
> -			i = ch - name;
> -	} else if (!yres_specified && was_digit) {
> -		/* catch mode that begins with digits but has no 'x' */
> -		i = 0;
> +	/* Locate the end of the name / resolution, and parse it */
> +	if (bpp_ptr && refresh_ptr) {
> +		mode_end = min(bpp_off, refresh_off);
> +	} else if (bpp_ptr) {
> +		mode_end = bpp_off;
> +	} else if (refresh_ptr) {
> +		mode_end = refresh_off;
> +	} else {
> +		mode_end = strlen(name);
> +		parse_extras = true;
>  	}
> -done:
> -	if (i >= 0) {
> -		pr_warn("[drm] parse error at position %i in video mode '%s'\n",
> -			i, name);
> -		mode->specified = false;
> +
> +	ret = drm_mode_parse_cmdline_res_mode(name, mode_end,
> +					      parse_extras,
> +					      connector,
> +					      mode);
> +	if (ret)
>  		return false;
> -	}
> +	mode->specified = true;
>  
> -	if (res_specified) {
> -		mode->specified = true;
> -		mode->xres = xres;
> -		mode->yres = yres;
> +	if (bpp_ptr) {
> +		ret = drm_mode_parse_cmdline_bpp(bpp_ptr, &bpp_end_ptr, mode);
> +		if (ret)
> +			return false;
>  	}
>  
> -	if (refresh_specified) {
> -		mode->refresh_specified = true;
> -		mode->refresh = refresh;
> +	if (refresh_ptr) {
> +		ret = drm_mode_parse_cmdline_refresh(refresh_ptr,
> +						     &refresh_end_ptr, mode);
> +		if (ret)
> +			return false;
>  	}
>  
> -	if (bpp_specified) {
> -		mode->bpp_specified = true;
> -		mode->bpp = bpp;
> +	/*
> +	 * Locate the end of the bpp / refresh, and parse the extras
> +	 * if relevant
> +	 */
> +	if (bpp_ptr && refresh_ptr)
> +		extra_ptr = max(bpp_end_ptr, refresh_end_ptr);
> +	else if (bpp_ptr)
> +		extra_ptr = bpp_end_ptr;
> +	else if (refresh_ptr)
> +		extra_ptr = refresh_end_ptr;
> +
> +	if (extra_ptr) {
> +		int remaining = strlen(name) - (extra_ptr - name);
> +
> +		/*
> +		 * We still have characters to process, while
> +		 * we shouldn't have any
> +		 */
> +		if (remaining > 0)
> +			return false;
>  	}
> -	mode->rb = rb;
> -	mode->cvt = cvt;
> -	mode->interlace = interlace;
> -	mode->margins = margins;
> -	mode->force = force;
>  
>  	return true;
>  }
>