Hello Bruno,
are you sure that fbcon really uses the 1bpp mode and that it works correctly?
I tried to
match all var-settings to yours, and 1bpp support still seems broken. Well, a
workaround
would be doing it like you are: using 8bpp shadow memory and translating it to
packed
pixels (8px per byte) when doing LCD updates. I guess, for now that will be the
way to go.
I'll be there to investigate further if needed.
Thank you,
Stefan
Am 14.06.2014 14:35, schrieb Bruno Prémont:
> Hi Stefan,
>
> On Sat, 14 June 2014 Stefan Biereigel <ste...@biereigel.de> wrote:
>> CC: linux-console, linux-fbdev
>>
>> Hello Kernel Developers,
>> for a university assignment we are developing a frame buffer driver for a
>> monochrome
>> display. We succeeded so far in making a simple "RAM frame buffer" module,
>> which is needed
>> as the basis (we don't have read access to the RAM in the LCD).
>> We are using the system-default fb_ops (fb_sys_{read,write},
>> sys_{fillrect,copyarea,imageblit), and all is well when we use
>> bits_per_pixel = 8. When we
>> map a console to the RAM frame buffer (con2fbmap 1 1), do strg-alt-F1, type
>> some
>> characters there, we can then 'cat /dev/fb1' and plot the ram contents in
>> Matlab
>> (reshaping the data to be our display geometry first), where our typed
>> characters and the
>> console appear.
>>
>> If we however change bits_per_pixel to 1, and divide line_length by 8 (as it
>> should
>> represent the line length in bytes), this suddenly stops working: echo and
>> cat to fb1 work
>> as intended: We change our Matlab-Script to interpret every byte as 8
>> pixels, bytes
>> written into /dev/fb1 can be read out correctly. If we however map the
>> console to fb1, no
>> console output can be seen in RAM - it is (seemingly) filled with garbage.
>>
>> We're using fbcon as the console driver, and the first frame buffer for me
>> is intelfb. I
>> see, that the bitblitting-calls for every typed character are depth 1 and
>> have correct
>> geometry, but the whole bitblitting-builtin seems not to work for
>> bits_per_pixel = 1, i
>> tried it with a simple test image after the initialisation...
>>
>> Is this behavior intended or are we triggering a bug here (that no one
>> noticed, because
>> who in the world uses monochrome framebuffers these days..). I can't see any
>> comments that
>> monochrome consoles should not work with 1 bit per pixel. See the code below
>> if you spot
>> some errors (ignore some missing error handling and mediocre style for now,
>> please).
>
> fbcon on 1bpp frambuffer worked for me with picoLCD (though I have found no
> userspace
> framebuffer application willing to operate at 1bpp).
> Thus I allow for 1bpp or 8bpp and convert 8bpp to 1bpp for the picolcd. As
> for your case,
> picoLCD is "write-only" monochrome LCD backed by in-RAM shadow framebuffer.
>
> (see drivers/hid/hid-picolcd_fb.c)
>
> Bruno
>
>> Thank you for any help and input.
>> Best regards,
>> Stefan Biereigel
>>
>> 8<--- testfb.c
>>
>> #include <linux/init.h>
>> #include <linux/module.h>
>>
>> #include <linux/fb.h>
>> #include <linux/slab.h>
>> #include <linux/wait.h>
>> #include <linux/errno.h>
>> #include <linux/platform_device.h>
>>
>> #define DISPLAY_WIDTH 240
>> #define DISPLAY_HEIGHT 64
>> #define FB_MEM_SIZE (DISPLAY_WIDTH * DISPLAY_HEIGHT)/8
>>
>> static struct platform_device *testfb_device;
>>
>> static struct fb_ops fbops = {
>> .owner = THIS_MODULE,
>> .fb_fillrect = sys_fillrect,
>> .fb_copyarea = sys_copyarea,
>> .fb_imageblit = sys_imageblit,
>> .fb_read = fb_sys_read,
>> .fb_write = fb_sys_write,
>> .fb_sync = NULL,
>> };
>>
>> static int __init testfb_probe (struct platform_device *pdev) {
>> void *fb_mem = NULL;
>> struct fb_info *fbinfo = NULL;
>>
>> fb_mem = kzalloc(FB_MEM_SIZE, GFP_KERNEL);
>>
>> if (!fb_mem) {
>> pr_err("testfb: memory allocation for framebuffer failed\n");
>> return(-ENOMEM);
>> }
>> else
>> pr_debug("testfb: allocated framebuffer memory successfully\n");
>>
>> fbinfo = framebuffer_alloc(0, &pdev->dev);
>>
>> if (!fbinfo) {
>> pr_err("testfb: framebuffer_alloc() failed\n");
>> kfree(fb_mem);
>> return(-1);
>> }
>> else
>> pr_debug("testfb: framebuffer_alloc was successful\n");
>>
>> fbinfo->fix.smem_start = (unsigned long) fb_mem;
>> fbinfo->screen_base = (char __iomem *) fb_mem;
>> fbinfo->fix.smem_len = FB_MEM_SIZE;
>> fbinfo->fbops = &fbops;
>>
>> fbinfo->node = 0; /* ?int
>> */
>> fbinfo->device = &pdev->dev;
>> fbinfo->flags = FBINFO_DEFAULT; /* */
>> fbinfo->var.xres = DISPLAY_WIDTH; /*
>> visible resolution */
>> fbinfo->var.yres = DISPLAY_HEIGHT; /*
>> visible resolution */
>> fbinfo->var.xres_virtual = DISPLAY_WIDTH; /*
>> virtual resolution */
>> fbinfo->var.yres_virtual = DISPLAY_HEIGHT; /*
>> virtual resolution */
>> fbinfo->var.bits_per_pixel = 1; /* bits
>> per pixel */
>> fbinfo->var.activate = FB_ACTIVATE_NOW; /* set
>> values immediately (or vbl) */
>> fbinfo->var.sync = 0; /* ?see
>> FB_SYNC_* */
>> fbinfo->var.vmode = FB_VMODE_NONINTERLACED; /* non
>> interlaced, see FB_VMODE_* */
>> fbinfo->var.left_margin = 0;
>> fbinfo->var.right_margin = 0;
>> fbinfo->var.upper_margin = 0;
>> fbinfo->var.lower_margin = 0;
>> fbinfo->var.red.offset = 0;
>> fbinfo->var.red.length = fbinfo->var.bits_per_pixel;
>> fbinfo->var.green = fbinfo->var.red;
>> fbinfo->var.blue = fbinfo->var.red;
>> fbinfo->var.grayscale = 1;
>> strcpy(fbinfo->fix.id, "testfb"); /*
>> identifier, 16 byte */
>> fbinfo->fix.type = FB_TYPE_PACKED_PIXELS; /* pack
>> pixels to avoid overhead */
>> fbinfo->fix.visual = FB_VISUAL_MONO10; /*
>> Monochr. 1=Black 0=White */
>> fbinfo->fix.line_length = DISPLAY_WIDTH/8; /*
>> length of a line in bytes */
>> fbinfo->fix.accel = FB_ACCEL_NONE; /* no
>> hardware accelerator */
>> fbinfo->fix.xpanstep = 0;
>> fbinfo->fix.ypanstep = 0;
>> fbinfo->fix.ywrapstep = 0;
>>
>> if (register_framebuffer(fbinfo) < 0) {
>> pr_err("testfb: registering framebuffer failed\n");
>> kfree((void *) fbinfo->fix.smem_start);
>> framebuffer_release(fbinfo);
>> return(-1);
>> }
>> else
>> pr_debug("testfb: registered framebuffer\n");
>>
>> platform_set_drvdata(pdev, fbinfo);
>>
>> return 0;
>> }
>>
>> static int testfb_remove(struct platform_device *pdev) {
>> struct fb_info *fbinfo = NULL;
>>
>> fbinfo = platform_get_drvdata(pdev);
>>
>> if (!fbinfo) {
>> pr_err("testfb: unable to get fbinfo from pdev\n");
>> return(-1);
>> }
>>
>> if (unregister_framebuffer(fbinfo) < 0)
>> pr_err("testfb: unregistering framebuffer failed\n");
>> else
>> pr_debug("testfb: unregistered framebuffer\n");
>>
>> kfree((void *) fbinfo->fix.smem_start);
>>
>> framebuffer_release(fbinfo);
>>
>> return 0;
>> }
>>
>> static struct platform_driver testfb_driver = {
>> .probe = testfb_probe,
>> .remove = testfb_remove,
>> .driver = {
>> .name = "testfb",
>> },
>> };
>>
>> static int __init testfb_init(void)
>> {
>> int ret;
>>
>> ret = platform_driver_register(&testfb_driver);
>> if (!ret) {
>> testfb_device = platform_device_register_simple("testfb", 0,
>> NULL, 0);
>>
>> if (IS_ERR(testfb_device)) {
>> platform_driver_unregister(&testfb_driver);
>> ret = PTR_ERR(testfb_device);
>> } else {
>> pr_info("testfb: platform_device registered\n");
>> }
>>
>> }
>>
>> pr_info("testfb: module loaded\n");
>>
>> return 0;
>> }
>>
>> static void __exit testfb_exit(void)
>> {
>> platform_device_unregister(testfb_device);
>> platform_driver_unregister(&testfb_driver);
>>
>> pr_info("testfb: module unloaded\n");
>> }
>>
>> module_init(testfb_init);
>> module_exit(testfb_exit);
>>
>> MODULE_LICENSE("GPL v2");
>> MODULE_ALIAS("testfb");
>> MODULE_AUTHOR("Brian Fonfara");
>> MODULE_DESCRIPTION("Ein Modul zum Test der Linux
>> Framebuffer-Programmierung");
>> MODULE_DESCRIPTION("version 0.1");
>> --
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