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video: fbdev: ssd1307fb: Optimize screen updates

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Currently, each screen update triggers an I2C transfer of all screen
data, up to 1 KiB of data for a 128x64 display, which takes at least 20
ms in Fast mode.

Reduce the amount of transferred data by only updating the rectangle
that changed.  Remove the calls to ssd1307fb_set_col_range() and
ssd1307fb_set_page_range() during initialization, as
ssd1307fb_update_rect() now takes care of that.

Note that for now the optimized operation is only used for fillrect,
copyarea, and imageblit, which are used by fbcon.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727134730.3765898-5-geert@linux-m68k.org
This commit is contained in:
Geert Uytterhoeven 2021-07-27 15:47:29 +02:00 committed by Sam Ravnborg
parent 8a15af3b86
commit 251e48a1db
1 changed files with 29 additions and 21 deletions
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50
drivers/video/fbdev/ssd1307fb.c
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@ -186,16 +186,18 @@ static int ssd1307fb_set_page_range(struct ssd1307fb_par *par, u8 page_start,
return ssd1307fb_write_cmd(par->client, page_end); return ssd1307fb_write_cmd(par->client, page_end);
} }
static int ssd1307fb_update_display(struct ssd1307fb_par *par) static int ssd1307fb_update_rect(struct ssd1307fb_par *par, unsigned int x,
unsigned int y, unsigned int width,
unsigned int height)
{ {
struct ssd1307fb_array *array; struct ssd1307fb_array *array;
u8 *vmem = par->info->screen_buffer; u8 *vmem = par->info->screen_buffer;
unsigned int line_length = par->info->fix.line_length; unsigned int line_length = par->info->fix.line_length;
unsigned int pages = DIV_ROUND_UP(par->height, 8); unsigned int pages = DIV_ROUND_UP(y % 8 + height, 8);
u32 array_idx = 0; u32 array_idx = 0;
int ret, i, j, k; int ret, i, j, k;
array = ssd1307fb_alloc_array(par->width * pages, SSD1307FB_DATA); array = ssd1307fb_alloc_array(width * pages, SSD1307FB_DATA);
if (!array) if (!array)
return -ENOMEM; return -ENOMEM;
@ -228,13 +230,21 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
* (5) A4 B4 C4 D4 E4 F4 G4 H4 * (5) A4 B4 C4 D4 E4 F4 G4 H4
*/ */
for (i = 0; i < pages; i++) { ret = ssd1307fb_set_col_range(par, par->col_offset + x, width);
if (ret < 0)
goto out_free;
ret = ssd1307fb_set_page_range(par, par->page_offset + y / 8, pages);
if (ret < 0)
goto out_free;
for (i = y / 8; i < y / 8 + pages; i++) {
int m = 8; int m = 8;
/* Last page may be partial */ /* Last page may be partial */
if (i + 1 == pages && par->height % 8) if (8 * (i + 1) > par->height)
m = par->height % 8; m = par->height % 8;
for (j = 0; j < par->width; j++) { for (j = x; j < x + width; j++) {
u8 data = 0; u8 data = 0;
for (k = 0; k < m; k++) { for (k = 0; k < m; k++) {
@ -247,11 +257,17 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
} }
} }
ret = ssd1307fb_write_array(par->client, array, par->width * pages); ret = ssd1307fb_write_array(par->client, array, width * pages);
out_free:
kfree(array); kfree(array);
return ret; return ret;
} }
static int ssd1307fb_update_display(struct ssd1307fb_par *par)
{
return ssd1307fb_update_rect(par, 0, 0, par->width, par->height);
}
static ssize_t ssd1307fb_write(struct fb_info *info, const char __user *buf, static ssize_t ssd1307fb_write(struct fb_info *info, const char __user *buf,
size_t count, loff_t *ppos) size_t count, loff_t *ppos)
@ -301,21 +317,24 @@ static void ssd1307fb_fillrect(struct fb_info *info, const struct fb_fillrect *r
{ {
struct ssd1307fb_par *par = info->par; struct ssd1307fb_par *par = info->par;
sys_fillrect(info, rect); sys_fillrect(info, rect);
ssd1307fb_update_display(par); ssd1307fb_update_rect(par, rect->dx, rect->dy, rect->width,
rect->height);
} }
static void ssd1307fb_copyarea(struct fb_info *info, const struct fb_copyarea *area) static void ssd1307fb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{ {
struct ssd1307fb_par *par = info->par; struct ssd1307fb_par *par = info->par;
sys_copyarea(info, area); sys_copyarea(info, area);
ssd1307fb_update_display(par); ssd1307fb_update_rect(par, area->dx, area->dy, area->width,
area->height);
} }
static void ssd1307fb_imageblit(struct fb_info *info, const struct fb_image *image) static void ssd1307fb_imageblit(struct fb_info *info, const struct fb_image *image)
{ {
struct ssd1307fb_par *par = info->par; struct ssd1307fb_par *par = info->par;
sys_imageblit(info, image); sys_imageblit(info, image);
ssd1307fb_update_display(par); ssd1307fb_update_rect(par, image->dx, image->dy, image->width,
image->height);
} }
static const struct fb_ops ssd1307fb_ops = { static const struct fb_ops ssd1307fb_ops = {
@ -495,17 +514,6 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
if (ret < 0) if (ret < 0)
return ret; return ret;
/* Set column range */
ret = ssd1307fb_set_col_range(par, par->col_offset, par->width);
if (ret < 0)
return ret;
/* Set page range */
ret = ssd1307fb_set_page_range(par, par->page_offset,
DIV_ROUND_UP(par->height, 8));
if (ret < 0)
return ret;
/* Clear the screen */ /* Clear the screen */
ret = ssd1307fb_update_display(par); ret = ssd1307fb_update_display(par);
if (ret < 0) if (ret < 0)