Re: [v2,1/4] fbdev/efifb: Replace references to global screen_info by local pointer

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Hi,


On 2023/12/4 17:27, Thomas Zimmermann wrote:
Get the global screen_info's address once and access the data via
this pointer. Limits the use of global state.

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>

Reviewed-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>


I have applied the whole series and do a simple test with efifb:
Yeah, still works!

$ dmesg | grep efifb

[    0.373800] efifb: probing for efifb
[    0.373816] efifb: framebuffer at 0xe0030000000, using 5120k, total 5120k
[    0.373818] efifb: mode is 1280x1024x32, linelength=5120, pages=1
[    0.373820] efifb: scrolling: redraw
[    0.373821] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0


---
  drivers/video/fbdev/efifb.c | 113 ++++++++++++++++++------------------
  1 file changed, 58 insertions(+), 55 deletions(-)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index f9b4ddd592ce4..6cbb65bbe1110 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -147,10 +147,9 @@ static bool efifb_bgrt_sanity_check(struct screen_info *si, u32 bmp_width)
  }
  #endif
-static void efifb_show_boot_graphics(struct fb_info *info)
+static void efifb_show_boot_graphics(struct fb_info *info, struct screen_info *si)

I think, we probably can add a const modifier for the function
which doesn't modify our local the screen_info instance in the future.

static void efifb_show_boot_graphics(struct fb_info *info, const struct screen_info *si)

Since screen_info is mostly used to provide information.


  {
  	u32 bmp_width, bmp_height, bmp_pitch, dst_x, y, src_y;
-	struct screen_info *si = &screen_info;
  	struct bmp_file_header *file_header;
  	struct bmp_dib_header *dib_header;
  	void *bgrt_image = NULL;
@@ -282,7 +281,7 @@ static const struct fb_ops efifb_ops = {
  	.fb_setcolreg	= efifb_setcolreg,
  };
-static int efifb_setup(char *options)
+static int efifb_setup(struct screen_info *si, char *options)
  {
  	char *this_opt;
@@ -290,16 +289,16 @@ static int efifb_setup(char *options)
  		while ((this_opt = strsep(&options, ",")) != NULL) {
  			if (!*this_opt) continue;
- efifb_setup_from_dmi(&screen_info, this_opt);
+			efifb_setup_from_dmi(si, this_opt);
if (!strncmp(this_opt, "base:", 5))
-				screen_info.lfb_base = simple_strtoul(this_opt+5, NULL, 0);
+				si->lfb_base = simple_strtoul(this_opt+5, NULL, 0);
  			else if (!strncmp(this_opt, "stride:", 7))
-				screen_info.lfb_linelength = simple_strtoul(this_opt+7, NULL, 0) * 4;
+				si->lfb_linelength = simple_strtoul(this_opt+7, NULL, 0) * 4;
  			else if (!strncmp(this_opt, "height:", 7))
-				screen_info.lfb_height = simple_strtoul(this_opt+7, NULL, 0);
+				si->lfb_height = simple_strtoul(this_opt+7, NULL, 0);
  			else if (!strncmp(this_opt, "width:", 6))
-				screen_info.lfb_width = simple_strtoul(this_opt+6, NULL, 0);
+				si->lfb_width = simple_strtoul(this_opt+6, NULL, 0);
  			else if (!strcmp(this_opt, "nowc"))
  				mem_flags &= ~EFI_MEMORY_WC;
  			else if (!strcmp(this_opt, "nobgrt"))
@@ -310,15 +309,15 @@ static int efifb_setup(char *options)
  	return 0;
  }
-static inline bool fb_base_is_valid(void)
+static inline bool fb_base_is_valid(struct screen_info *si)
  {
-	if (screen_info.lfb_base)
+	if (si->lfb_base)
  		return true;
- if (!(screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE))
+	if (!(si->capabilities & VIDEO_CAPABILITY_64BIT_BASE))
  		return false;
- if (screen_info.ext_lfb_base)
+	if (si->ext_lfb_base)
  		return true;
return false;
@@ -329,7 +328,10 @@ static ssize_t name##_show(struct device *dev,				\
  			   struct device_attribute *attr,		\
  			   char *buf)					\
  {									\
-	return sprintf(buf, fmt "\n", (screen_info.lfb_##name));	\
+	struct screen_info *si = dev_get_platdata(dev);			\
+	if (!si)							\
+		return -ENODEV;						\
+	return sprintf(buf, fmt "\n", (si->lfb_##name));		\
  }									\
  static DEVICE_ATTR_RO(name)
@@ -356,6 +358,7 @@ static u64 bar_offset; static int efifb_probe(struct platform_device *dev)
  {
+	struct screen_info *si = &screen_info;
  	struct fb_info *info;
  	struct efifb_par *par;
  	int err, orientation;
@@ -365,48 +368,48 @@ static int efifb_probe(struct platform_device *dev)
  	char *option = NULL;
  	efi_memory_desc_t md;
- if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
+	if (si->orig_video_isVGA != VIDEO_TYPE_EFI || pci_dev_disabled)
  		return -ENODEV;
if (fb_get_options("efifb", &option))
  		return -ENODEV;
-	efifb_setup(option);
+	efifb_setup(si, option);
/* We don't get linelength from UGA Draw Protocol, only from
  	 * EFI Graphics Protocol.  So if it's not in DMI, and it's not
  	 * passed in from the user, we really can't use the framebuffer.
  	 */
-	if (!screen_info.lfb_linelength)
+	if (!si->lfb_linelength)
  		return -ENODEV;
- if (!screen_info.lfb_depth)
-		screen_info.lfb_depth = 32;
-	if (!screen_info.pages)
-		screen_info.pages = 1;
-	if (!fb_base_is_valid()) {
+	if (!si->lfb_depth)
+		si->lfb_depth = 32;
+	if (!si->pages)
+		si->pages = 1;
+	if (!fb_base_is_valid(si)) {
  		printk(KERN_DEBUG "efifb: invalid framebuffer address\n");
  		return -ENODEV;
  	}
  	printk(KERN_INFO "efifb: probing for efifb\n");
/* just assume they're all unset if any are */
-	if (!screen_info.blue_size) {
-		screen_info.blue_size = 8;
-		screen_info.blue_pos = 0;
-		screen_info.green_size = 8;
-		screen_info.green_pos = 8;
-		screen_info.red_size = 8;
-		screen_info.red_pos = 16;
-		screen_info.rsvd_size = 8;
-		screen_info.rsvd_pos = 24;
+	if (!si->blue_size) {
+		si->blue_size = 8;
+		si->blue_pos = 0;
+		si->green_size = 8;
+		si->green_pos = 8;
+		si->red_size = 8;
+		si->red_pos = 16;
+		si->rsvd_size = 8;
+		si->rsvd_pos = 24;
  	}


Yeah, Here the efifb modified our local screen_info instance, but this is not relevant to your patch.


- efifb_fix.smem_start = screen_info.lfb_base;
+	efifb_fix.smem_start = si->lfb_base;
- if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) {
+	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE) {
  		u64 ext_lfb_base;
- ext_lfb_base = (u64)(unsigned long)screen_info.ext_lfb_base << 32;
+		ext_lfb_base = (u64)(unsigned long)si->ext_lfb_base << 32;
  		efifb_fix.smem_start |= ext_lfb_base;
  	}
@@ -417,10 +420,10 @@ static int efifb_probe(struct platform_device *dev)
  		efifb_fix.smem_start = bar_resource->start + bar_offset;
  	}
- efifb_defined.bits_per_pixel = screen_info.lfb_depth;
-	efifb_defined.xres = screen_info.lfb_width;
-	efifb_defined.yres = screen_info.lfb_height;
-	efifb_fix.line_length = screen_info.lfb_linelength;
+	efifb_defined.bits_per_pixel = si->lfb_depth;
+	efifb_defined.xres = si->lfb_width;
+	efifb_defined.yres = si->lfb_height;
+	efifb_fix.line_length = si->lfb_linelength;
/* size_vmode -- that is the amount of memory needed for the
  	 *                 used video mode, i.e. the minimum amount of
@@ -430,7 +433,7 @@ static int efifb_probe(struct platform_device *dev)
  	/*   size_total -- all video memory we have. Used for
  	 *                 entries, ressource allocation and bounds
  	 *                 checking. */
-	size_total = screen_info.lfb_size;
+	size_total = si->lfb_size;
  	if (size_total < size_vmode)
  		size_total = size_vmode;
@@ -512,7 +515,7 @@ static int efifb_probe(struct platform_device *dev)
  	pr_info("efifb: mode is %dx%dx%d, linelength=%d, pages=%d\n",
  	       efifb_defined.xres, efifb_defined.yres,
  	       efifb_defined.bits_per_pixel, efifb_fix.line_length,
-	       screen_info.pages);
+	       si->pages);
efifb_defined.xres_virtual = efifb_defined.xres;
  	efifb_defined.yres_virtual = efifb_fix.smem_len /
@@ -526,26 +529,26 @@ static int efifb_probe(struct platform_device *dev)
  	efifb_defined.left_margin  = (efifb_defined.xres / 8) & 0xf8;
  	efifb_defined.hsync_len    = (efifb_defined.xres / 8) & 0xf8;
- efifb_defined.red.offset = screen_info.red_pos;
-	efifb_defined.red.length    = screen_info.red_size;
-	efifb_defined.green.offset  = screen_info.green_pos;
-	efifb_defined.green.length  = screen_info.green_size;
-	efifb_defined.blue.offset   = screen_info.blue_pos;
-	efifb_defined.blue.length   = screen_info.blue_size;
-	efifb_defined.transp.offset = screen_info.rsvd_pos;
-	efifb_defined.transp.length = screen_info.rsvd_size;
+	efifb_defined.red.offset    = si->red_pos;
+	efifb_defined.red.length    = si->red_size;
+	efifb_defined.green.offset  = si->green_pos;
+	efifb_defined.green.length  = si->green_size;
+	efifb_defined.blue.offset   = si->blue_pos;
+	efifb_defined.blue.length   = si->blue_size;
+	efifb_defined.transp.offset = si->rsvd_pos;
+	efifb_defined.transp.length = si->rsvd_size;
pr_info("efifb: %s: "
  	       "size=%d:%d:%d:%d, shift=%d:%d:%d:%d\n",
  	       "Truecolor",
-	       screen_info.rsvd_size,
-	       screen_info.red_size,
-	       screen_info.green_size,
-	       screen_info.blue_size,
-	       screen_info.rsvd_pos,
-	       screen_info.red_pos,
-	       screen_info.green_pos,
-	       screen_info.blue_pos);
+	       si->rsvd_size,
+	       si->red_size,
+	       si->green_size,
+	       si->blue_size,
+	       si->rsvd_pos,
+	       si->red_pos,
+	       si->green_pos,
+	       si->blue_pos);
efifb_fix.ypanstep = 0;
  	efifb_fix.ywrapstep = 0;




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