[PATCH 0/2] Add monochrome framebuffer support to simple-framebuffer

[PATCH 0/2] Add monochrome framebuffer support to simple-framebuffer

[Sebastian Raase]

This patch series adds support for monochrome framebuffers (1 bpp, packed-pixel)
to simple-framebuffer.

Monochrome framebuffers require far less video memory and bandwidth than
16bpp or 32bpp framebuffers, making them useful for small devices or FPGA
implementations.

Sebastian Raase (2):
  fbdev: simplefb: Add mono framebuffer format
  dt-bindings: display: simple-framebuffer: Document mono format

 .../devicetree/bindings/display/simple-framebuffer.yaml         | 2 ++
 drivers/video/fbdev/simplefb.c                                  | 2 ++
 include/linux/platform_data/simplefb.h                          | 1 +
 3 files changed, 5 insertions(+)

-- 
2.47.3

[PATCH 1/2] fbdev: simplefb: Add mono framebuffer format

[Sebastian Raase]

Add a new simple-framebuffer format for monochrome 1 bit-per-pixel
framebuffers. Monochrome framebuffers are not true color, so their
visual is set to FB_VISUAL_MONO10 (set pixels are bright).

Signed-off-by: Sebastian Raase <linux@sraa.de>
---
 drivers/video/fbdev/simplefb.c         | 2 ++
 include/linux/platform_data/simplefb.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 60e5dcec201f..4662101885ec 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -583,6 +583,8 @@ static int simplefb_probe(struct platform_device *pdev)
 	info->fix.smem_start = mem->start;
 	info->fix.smem_len = resource_size(mem);
 	info->fix.line_length = params.stride;
+	if (params.format->bits_per_pixel == 1)
+		info->fix.visual = FB_VISUAL_MONO10;
 
 	info->var = simplefb_var;
 	info->var.xres = params.width;
diff --git a/include/linux/platform_data/simplefb.h b/include/linux/platform_data/simplefb.h
index 4f94d52ac99f..9b6d822145c9 100644
--- a/include/linux/platform_data/simplefb.h
+++ b/include/linux/platform_data/simplefb.h
@@ -15,6 +15,7 @@
 /* format array, use it to initialize a "struct simplefb_format" array */
 #define SIMPLEFB_FORMATS \
 { \
+	{ "mono", 1, {0, 1}, {0, 1}, {0, 1}, {0, 0}, DRM_FORMAT_R1 }, \
 	{ "r5g6b5", 16, {11, 5}, {5, 6}, {0, 5}, {0, 0}, DRM_FORMAT_RGB565 }, \
 	{ "r5g5b5a1", 16, {11, 5}, {6, 5}, {1, 5}, {0, 1}, DRM_FORMAT_RGBA5551 }, \
 	{ "x1r5g5b5", 16, {10, 5}, {5, 5}, {0, 5}, {0, 0}, DRM_FORMAT_XRGB1555 }, \
-- 
2.47.3

Re: [PATCH 1/2] fbdev: simplefb: Add mono framebuffer format

[Helge Deller]

On 11/4/26 03:34, Sebastian Raase wrote:
> Add a new simple-framebuffer format for monochrome 1 bit-per-pixel
> framebuffers. Monochrome framebuffers are not true color, so their
> visual is set to FB_VISUAL_MONO10 (set pixels are bright).
> 
> Signed-off-by: Sebastian Raase <linux@sraa.de>
> ---
>   drivers/video/fbdev/simplefb.c         | 2 ++
>   include/linux/platform_data/simplefb.h | 1 +
>   2 files changed, 3 insertions(+)
series applied to fbdev git tree.

Thanks!
Helge

Re: [PATCH 1/2] fbdev: simplefb: Add mono framebuffer format

[Thomas Zimmermann]

Hi Helge

Am 11.11.26 um 00:25 schrieb Helge Deller:
> On 11/4/26 03:34, Sebastian Raase wrote:
>> Add a new simple-framebuffer format for monochrome 1 bit-per-pixel
>> framebuffers. Monochrome framebuffers are not true color, so their
>> visual is set to FB_VISUAL_MONO10 (set pixels are bright).
>>
>> Signed-off-by: Sebastian Raase <linux@sraa.de>
>> ---
>>   drivers/video/fbdev/simplefb.c         | 2 ++
>>   include/linux/platform_data/simplefb.h | 1 +
>>   2 files changed, 3 insertions(+)
> series applied to fbdev git tree.

Isn't that a bit premature? There's no use-case give; except 
because-we-can.  And doesn't it require a review from DT maintainers?

Best regards
Thomas

>
> Thanks!
> Helge

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)

Re: [PATCH 1/2] fbdev: simplefb: Add mono framebuffer format

[Helge Deller]

On 11/11/26 16:27, Thomas Zimmermann wrote:
> Hi Helge
> 
> Am 11.11.26 um 00:25 schrieb Helge Deller:
>> On 11/4/26 03:34, Sebastian Raase wrote:
>>> Add a new simple-framebuffer format for monochrome 1 bit-per-pixel
>>> framebuffers. Monochrome framebuffers are not true color, so their
>>> visual is set to FB_VISUAL_MONO10 (set pixels are bright).
>>>
>>> Signed-off-by: Sebastian Raase <linux@sraa.de>
>>> ---
>>>   drivers/video/fbdev/simplefb.c         | 2 ++
>>>   include/linux/platform_data/simplefb.h | 1 +
>>>   2 files changed, 3 insertions(+)
>> series applied to fbdev git tree.
> 
> Isn't that a bit premature? There's no use-case give; except because-
> we-can.  And doesn't it require a review from DT maintainers?

I'm happy to add any Reviews or Acks, or drop it again if there are any objections.

Helge

[PATCH 2/2] dt-bindings: display: simple-framebuffer: Document mono format

[Sebastian Raase]

This is a 1 bit-per-pixel monochrome format, with 8 pixels/byte.

Signed-off-by: Sebastian Raase <linux@sraa.de>
---
 .../devicetree/bindings/display/simple-framebuffer.yaml         | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml
index 45ffdebc9d86..c627ec088434 100644
--- a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml
+++ b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml
@@ -94,6 +94,7 @@ properties:
   format:
     description: >
       Format of the framebuffer:
+        * `mono` - 1-bit packed pixels, 8 pixels/byte
         * `a1r5g5b5` - 16-bit pixels, d[15]=a, d[14:10]=r, d[9:5]=g, d[4:0]=b
         * `a2r10g10b10` - 32-bit pixels, d[31:30]=a, d[29:20]=r, d[19:10]=g, d[9:0]=b
         * `a8b8g8r8` - 32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r
@@ -106,6 +107,7 @@ properties:
         * `x8r8g8b8` - 32-bit pixels, d[23:16]=r, d[15:8]=g, d[7:0]=b
         * `x8b8g8r8` - 32-bit pixels, d[23:16]=b, d[15:8]=g, d[7:0]=r
     enum:
+      - mono
       - a1r5g5b5
       - a2r10g10b10
       - a8b8g8r8
-- 
2.47.3

Re: [PATCH 0/2] Add monochrome framebuffer support to simple-framebuffer

[Hans de Goede]

Hi Sebastian,

On 4-Nov-26 03:34, Sebastian Raase wrote:
> This patch series adds support for monochrome framebuffers (1 bpp, packed-pixel)
> to simple-framebuffer.
> 
> Monochrome framebuffers require far less video memory and bandwidth than
> 16bpp or 32bpp framebuffers, making them useful for small devices or FPGA
> implementations.

Thank you for your patch-series and I see that Helge has just
applied this to the fbdev tree.

Have you considered also extending the simpledrm driver to also
support these monochrome formats there ?

Most Linux distributions now a days have switched from using simplefb
to using simpledrm.

But I must admit I've no idea how well the drm subsys / kernel-mode-
setting API handles monochrome formats.

Regards,

Hans

Re: [PATCH 0/2] Add monochrome framebuffer support to simple-framebuffer

[Thomas Zimmermann]

Hi

Am 11.11.26 um 12:15 schrieb Hans de Goede:
> Hi Sebastian,
>
> On 4-Nov-26 03:34, Sebastian Raase wrote:
>> This patch series adds support for monochrome framebuffers (1 bpp, packed-pixel)
>> to simple-framebuffer.
>>
>> Monochrome framebuffers require far less video memory and bandwidth than
>> 16bpp or 32bpp framebuffers, making them useful for small devices or FPGA
>> implementations.
> Thank you for your patch-series and I see that Helge has just
> applied this to the fbdev tree.
>
> Have you considered also extending the simpledrm driver to also
> support these monochrome formats there ?
>
> Most Linux distributions now a days have switched from using simplefb
> to using simpledrm.
>
> But I must admit I've no idea how well the drm subsys / kernel-mode-
> setting API handles monochrome formats.

Only kind of. We either support it natively if the compositor can handle 
it, or we convert from XRGB8888 to the internal pixel format. But our 
helpers for converting pixel formats expect 8-bit per pixel at a 
minimum. All the drivers with lower pixel size do some kind of 
workaround. I'd love to see better support, but had no time to work on it.

Best regards
Thomas


>
> Regards,
>
> Hans
>
>
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)