[PATCH] vfb: fix video mode and line_length being set when loaded

Currently, when loading the vfb module, the newly created fbdev
has a line_length of 0, and its video mode would be PSEUDOCOLOR
regardless of color depth. (The former could be worked around by
calling the FBIOPUT_VSCREENINFO ioctl with having the FBACTIVIATE_FORCE
flag set.) This patch automatically sets the line_length correctly,
and the video mode is derived from the bit depth now as well.

Thanks to Geert Uytterhoeven for confirming the bug and helping me with
the patch.

Output of `fbset -i' before the patch:
mode "1366x768-60"
    # D: 72.432 MHz, H: 47.403 kHz, V: 60.004 Hz
    geometry 1366 768 1366 768 32
    timings 13806 120 10 14 3 32 5
    rgba 8/0,8/8,8/16,8/24
endmode

Frame buffer device information:
    Name        : Virtual FB
    Address     : 0xffffaa1405d85000
    Size        : 4196352
    Type        : PACKED PIXELS
    Visual      : PSEUDOCOLOR
    XPanStep    : 1
    YPanStep    : 1
    YWrapStep   : 1
    LineLength  : 0                    <-- note this
    Accelerator : No

After:
mode "1366x768-60"
    # D: 72.432 MHz, H: 47.403 kHz, V: 60.004 Hz
    geometry 1366 768 1366 768 32
    timings 13806 120 10 14 3 32 5
    rgba 8/0,8/8,8/16,8/24
endmode

Frame buffer device information:
    Name        : Virtual FB
    Address     : 0xffffaa1405d85000
    Size        : 4196352
    Type        : PACKED PIXELS
    Visual      : TRUECOLOR
    XPanStep    : 1
    YPanStep    : 1
    YWrapStep   : 1
    LineLength  : 5464
    Accelerator : No

Thanks for your consideration,
Pieter "PoroCYon" Sluys

---
 drivers/video/fbdev/vfb.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c
index da653a080394..6e866fbaab8a 100644
--- a/drivers/video/fbdev/vfb.c
+++ b/drivers/video/fbdev/vfb.c

@@ -239,8 +239,25 @@ static int vfb_check_var(struct fb_var_screeninfo *var,
  */
 static int vfb_set_par(struct fb_info *info)
 {
+	switch (info->var.bits_per_pixel) {
+		case 1:
+			info->fix.visual = FB_VISUAL_MONO01;
+			break;
+		case 2:
+		case 4:
+		case 8:
+			info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+			break;
+		case 16:
+		case 24:
+		case 32:
+			info->fix.visual = FB_VISUAL_TRUECOLOR;
+			break;
+	}
+
 	info->fix.line_length = get_line_length(info->var.xres_virtual,
 						info->var.bits_per_pixel);
+
 	return 0;
 }

@@ -450,6 +467,8 @@ static int vfb_probe(struct platform_device *dev)
 		goto err2;
 	platform_set_drvdata(dev, info);

+	vfb_set_par(info);
+
 	fb_info(info, "Virtual frame buffer device, using %ldK of video memory\n",
 		videomemorysize >> 10);
 	return 0;
--

2.15.1

Hi Pieter,

On Wed, Dec 20, 2017 at 1:24 AM, Pieter "PoroCYon" Sluys
[off-list ref] wrote:

Currently, when loading the vfb module, the newly created fbdev
has a line_length of 0, and its video mode would be PSEUDOCOLOR
regardless of color depth. (The former could be worked around by
calling the FBIOPUT_VSCREENINFO ioctl with having the FBACTIVIATE_FORCE
flag set.) This patch automatically sets the line_length correctly,
and the video mode is derived from the bit depth now as well.

Thanks for your patch!
This bug was introduced in 2002, when converting the driver to the new
internal API.

Please add your "Signed-off-by", cfr.
Documentation/process/submitting-patches.rst.

You can drop the tests for 2 and 4, as these are no longer used by the driver.

With the above fixed:
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Geert Uytterhoeven:

Please add your "Signed-off-by", cfr.
Documentation/process/submitting-patches.rst.

Sorry I knew I would've messed up *something*.

You can drop the tests for 2 and 4, as these are no longer used by the driver.

Done that.

Cc: Bartlomiej Zolnierkiewicz <redacted>
Signed-off-by: Pieter "PoroCYon" Sluys <redacted>

---
 drivers/video/fbdev/vfb.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/video/fbdev/vfb.c b/drivers/video/fbdev/vfb.c
index da653a080394..5fb360283c6b 100644
--- a/drivers/video/fbdev/vfb.c
+++ b/drivers/video/fbdev/vfb.c

@@ -239,8 +239,23 @@ static int vfb_check_var(struct fb_var_screeninfo *var,
  */
 static int vfb_set_par(struct fb_info *info)
 {
+	switch (info->var.bits_per_pixel) {
+		case 1:
+			info->fix.visual = FB_VISUAL_MONO01;
+			break;
+		case 8:
+			info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+			break;
+		case 16:
+		case 24:
+		case 32:
+			info->fix.visual = FB_VISUAL_TRUECOLOR;
+			break;
+	}
+
 	info->fix.line_length = get_line_length(info->var.xres_virtual,
 						info->var.bits_per_pixel);
+
 	return 0;
 }

@@ -450,6 +465,8 @@ static int vfb_probe(struct platform_device *dev)
 		goto err2;
 	platform_set_drvdata(dev, info);

+	vfb_set_par(info);
+
 	fb_info(info, "Virtual frame buffer device, using %ldK of video memory\n",
 		videomemorysize >> 10);
 	return 0;
--

2.15.1

On Wednesday, December 20, 2017 02:53:00 PM Pieter PoroCYon Sluys wrote:

Geert Uytterhoeven:

quoted

Please add your "Signed-off-by", cfr.
Documentation/process/submitting-patches.rst.

Sorry I knew I would've messed up *something*.

quoted

You can drop the tests for 2 and 4, as these are no longer used by the driver.

Done that.

Cc: Bartlomiej Zolnierkiewicz <redacted>
Signed-off-by: Pieter "PoroCYon" Sluys <redacted>

I've queued your patch for 4.16 kernel (after fixing few minor
issues [*]), thanks!

[*] next time please remember to:

* always include full patch description in the later patch revisions

* put things that don't belong to patch description after "---" so
  they will not be included in the final commit

* in the later patch revisions include ChangeLog after "---" and also
  put patch version in the patch summary line / mail subject
  (i.e. "[PATCH v2] ...")

* add tags (i.e. "Reviewed-by: ...") from patch reviewers / testers
  into the patch description

* check your patch with scripts/checkpatch.pl tool and fix reported
  issues, i.e.:

ERROR: switch and case should be at the same indent
#69: FILE: drivers/video/fbdev/vfb.c:242:
+       switch (info->var.bits_per_pixel) {
+               case 1:
[...]
+               case 8:
[...]
+               case 16:
+               case 24:
+               case 32:

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics