Commit b0020d8a authored by Marko Kohtala's avatar Marko Kohtala Committed by Bartlomiej Zolnierkiewicz
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video: ssd1307fb: Handle width and height that are not multiple of 8 



Some displays have dimensions that are not multiple of eight, for example
height of 36, but the driver divided the dimensions by 8. Defining display
to the next multiple of 8 is not good as then the display registers get
configured to dimensions that do not match. This contradicts intructions
by some display manufacturers.

Use DIV_ROUND_UP to multiple of 8 when needed so correct values can be
used.

The ssd1307fb_update_display bit reordering receives a simplification in
the process.

Signed-off-by: default avatarMarko Kohtala <marko.kohtala@okoko.fi>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Michal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618074111.9309-5-marko.kohtala@okoko.fi
parent dd978283

drivers/video/fbdev/ssd1307fb.c

+17 −13
Original line number Diff line number Diff line
@@ -150,10 +150,11 @@ static void ssd1307fb_update_display(struct ssd1307fb_par *par) 
{

	struct ssd1307fb_array *array;

	u8 *vmem = par->info->screen_buffer;

	unsigned int line_length = par->info->fix.line_length;

	unsigned int pages = DIV_ROUND_UP(par->height, 8);

	int i, j, k;



	array = ssd1307fb_alloc_array(par->width * par->height / 8,

				      SSD1307FB_DATA);

	array = ssd1307fb_alloc_array(par->width * pages, SSD1307FB_DATA);

	if (!array)

		return;
@@ -186,22 +187,24 @@ static void ssd1307fb_update_display(struct ssd1307fb_par *par) 
	 *  (5) A4 B4 C4 D4 E4 F4 G4 H4

	 */



	for (i = 0; i < (par->height / 8); i++) {

	for (i = 0; i < pages; i++) {

		for (j = 0; j < par->width; j++) {

			int m = 8;

			u32 array_idx = i * par->width + j;

			array->data[array_idx] = 0;

			for (k = 0; k < 8; k++) {

				u32 page_length = par->width * i;

				u32 index = page_length + (par->width * k + j) / 8;

				u8 byte = *(vmem + index);

				u8 bit = byte & (1 << (j % 8));

				bit = bit >> (j % 8);

			/* Last page may be partial */

			if (i + 1 == pages && par->height % 8)

				m = par->height % 8;

			for (k = 0; k < m; k++) {

				u8 byte = vmem[(8 * i + k) * line_length +

					       j / 8];

				u8 bit = (byte >> (j % 8)) & 1;

				array->data[array_idx] |= bit << k;

			}

		}

	}



	ssd1307fb_write_array(par->client, array, par->width * par->height / 8);

	ssd1307fb_write_array(par->client, array, par->width * pages);

	kfree(array);

}
@@ -437,7 +440,8 @@ static int ssd1307fb_init(struct ssd1307fb_par *par) 
		return ret;



	ret = ssd1307fb_write_cmd(par->client,

				  par->page_offset + (par->height / 8) - 1);

				  par->page_offset +

				  DIV_ROUND_UP(par->height, 8) - 1);

	if (ret < 0)

		return ret;
@@ -615,7 +619,7 @@ static int ssd1307fb_probe(struct i2c_client *client, 
	par->dclk_div = par->device_info->default_dclk_div;

	par->dclk_frq = par->device_info->default_dclk_frq;



	vmem_size = par->width * par->height / 8;

	vmem_size = DIV_ROUND_UP(par->width, 8) * par->height;



	vmem = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,

					get_order(vmem_size));
@@ -638,7 +642,7 @@ static int ssd1307fb_probe(struct i2c_client *client, 


	info->fbops = &ssd1307fb_ops;

	info->fix = ssd1307fb_fix;

	info->fix.line_length = par->width / 8;

	info->fix.line_length = DIV_ROUND_UP(par->width, 8);

	info->fbdefio = ssd1307fb_defio;



	info->var = ssd1307fb_var;

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