Hi all,
This patch series optimizes console operations on ssd1307fb, after the
customary fixes and cleanups.
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. While many displays are smaller, and thus require less
data to be transferred, 20 ms is still an optimistic value, as the
actual data transfer may be much slower, especially on bitbanged I2C
drivers. After this series, the amount of data transfer is reduced, as
fillrect, copyarea, and imageblit only update the rectangle that
changed.
This has been tested on an Adafruit FeatherWing OLED with an SSD1306
controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
usage for blinking the cursor from more than 70% to ca. 10%.
Thanks for your comments!
Geert Uytterhoeven (5):
video: fbdev: ssd1307fb: Propagate errors via
ssd1307fb_update_display()
video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
video: fbdev: ssd1307fb: Optimize screen updates
video: fbdev: ssd1307fb: Cache address ranges
drivers/video/fbdev/ssd1307fb.c | 143 +++++++++++++++++++++-----------
1 file changed, 96 insertions(+), 47 deletions(-)
--
2.25.1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
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 call to ssd1307fb_set_address_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 <[email protected]>
---
drivers/video/fbdev/ssd1307fb.c | 43 ++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index cfa27ea0feab4f01..8e3d4be74723b9bf 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -184,16 +184,18 @@ static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
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;
u8 *vmem = par->info->screen_buffer;
unsigned int line_length = par->info->fix.line_length;
- unsigned int pages = DIV_ROUND_UP(par->height, 8);
+ unsigned int pages = DIV_ROUND_UP(height + y % 8, 8);
u32 array_idx = 0;
int ret, i, j, k;
- array = ssd1307fb_alloc_array(par->width * pages, SSD1307FB_DATA);
+ array = ssd1307fb_alloc_array(width * pages, SSD1307FB_DATA);
if (!array)
return -ENOMEM;
@@ -226,13 +228,18 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
* (5) A4 B4 C4 D4 E4 F4 G4 H4
*/
- for (i = 0; i < pages; i++) {
+ ret = ssd1307fb_set_address_range(par, par->col_offset + x, width,
+ par->page_offset + y / 8, pages);
+ if (ret < 0)
+ goto out_free;
+
+ for (i = y / 8; i < y / 8 + pages; i++) {
int m = 8;
/* Last page may be partial */
- if (i + 1 == pages && par->height % 8)
+ if (8 * (i + 1) > par->height)
m = par->height % 8;
- for (j = 0; j < par->width; j++) {
+ for (j = x; j < x + width; j++) {
u8 data = 0;
for (k = 0; k < m; k++) {
@@ -245,11 +252,17 @@ 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);
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,
size_t count, loff_t *ppos)
@@ -299,21 +312,24 @@ static void ssd1307fb_fillrect(struct fb_info *info, const struct fb_fillrect *r
{
struct ssd1307fb_par *par = info->par;
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)
{
struct ssd1307fb_par *par = info->par;
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)
{
struct ssd1307fb_par *par = info->par;
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 = {
@@ -493,13 +509,6 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
if (ret < 0)
return ret;
- /* Set column and page range */
- ret = ssd1307fb_set_address_range(par, par->col_offset, par->width,
- par->page_offset,
- DIV_ROUND_UP(par->height, 8));
- if (ret < 0)
- return ret;
-
/* Clear the screen */
ret = ssd1307fb_update_display(par);
if (ret < 0)
--
2.25.1
Extract the code to set the column and page ranges into a helper
function.
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/video/fbdev/ssd1307fb.c | 61 +++++++++++++++++++--------------
1 file changed, 36 insertions(+), 25 deletions(-)
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 6d7bd025bca1a175..cfa27ea0feab4f01 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -152,6 +152,38 @@ static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
return ret;
}
+static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
+ u8 cols, u8 page_start, u8 pages)
+{
+ u8 col_end = col_start + cols - 1;
+ u8 page_end = page_start + pages - 1;
+ int ret;
+
+ /* Set column range */
+ ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
+ if (ret < 0)
+ return ret;
+
+ ret = ssd1307fb_write_cmd(par->client, col_start);
+ if (ret < 0)
+ return ret;
+
+ ret = ssd1307fb_write_cmd(par->client, col_end);
+ if (ret < 0)
+ return ret;
+
+ /* Set page range */
+ ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
+ if (ret < 0)
+ return ret;
+
+ ret = ssd1307fb_write_cmd(par->client, page_start);
+ if (ret < 0)
+ return ret;
+
+ return ssd1307fb_write_cmd(par->client, page_end);
+}
+
static int ssd1307fb_update_display(struct ssd1307fb_par *par)
{
struct ssd1307fb_array *array;
@@ -461,31 +493,10 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
if (ret < 0)
return ret;
- /* Set column range */
- ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COL_RANGE);
- if (ret < 0)
- return ret;
-
- ret = ssd1307fb_write_cmd(par->client, par->col_offset);
- if (ret < 0)
- return ret;
-
- ret = ssd1307fb_write_cmd(par->client, par->col_offset + par->width - 1);
- if (ret < 0)
- return ret;
-
- /* Set page range */
- ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_PAGE_RANGE);
- if (ret < 0)
- return ret;
-
- ret = ssd1307fb_write_cmd(par->client, par->page_offset);
- if (ret < 0)
- return ret;
-
- ret = ssd1307fb_write_cmd(par->client,
- par->page_offset +
- DIV_ROUND_UP(par->height, 8) - 1);
+ /* Set column and page range */
+ ret = ssd1307fb_set_address_range(par, par->col_offset, par->width,
+ par->page_offset,
+ DIV_ROUND_UP(par->height, 8));
if (ret < 0)
return ret;
--
2.25.1
Hi Sam,
On Wed, Jul 14, 2021 at 5:27 PM Sam Ravnborg <[email protected]> wrote:
> On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > This patch series optimizes console operations on ssd1307fb, after the
> > customary fixes and cleanups.
>
> What is required to to have a drm driver that could do the same?
Add monochrome support to DRM?
> Note: I will take a look at the patches a bit later.
TIA!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
Hi Sam,
On Mon, Jul 19, 2021 at 9:23 PM Sam Ravnborg <[email protected]> wrote:
> On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > This patch series optimizes console operations on ssd1307fb, after the
> > customary fixes and cleanups.
> >
> > 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. While many displays are smaller, and thus require less
> > data to be transferred, 20 ms is still an optimistic value, as the
> > actual data transfer may be much slower, especially on bitbanged I2C
> > drivers. After this series, the amount of data transfer is reduced, as
> > fillrect, copyarea, and imageblit only update the rectangle that
> > changed.
> >
> > This has been tested on an Adafruit FeatherWing OLED with an SSD1306
> > controller and a 128x32 OLED, connected to an OrangeCrab ECP5 FPGA board
> > running a 64 MHz VexRiscv RISC-V softcore, where it reduced the CPU
> > usage for blinking the cursor from more than 70% to ca. 10%.
> >
> > Thanks for your comments!
> >
> > Geert Uytterhoeven (5):
> > video: fbdev: ssd1307fb: Propagate errors via
> > ssd1307fb_update_display()
> > video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
> > video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range()
> > video: fbdev: ssd1307fb: Optimize screen updates
> > video: fbdev: ssd1307fb: Cache address ranges
>
> A few comments left for a couple of patches.
> The remaining patches are:
> Acked-by: Sam Ravnborg <[email protected]>
Thank you!
> Do you have commit rights to drm-misc-next?
No I have not (and I don't think I should).
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
Hi Sam,
On Mon, Jul 19, 2021 at 9:07 PM Sam Ravnborg <[email protected]> wrote:
> On Wed, Jul 14, 2021 at 04:58:02PM +0200, Geert Uytterhoeven wrote:
> > Extract the code to set the column and page ranges into a helper
> > function.
> >
> > Signed-off-by: Geert Uytterhoeven <[email protected]>
> > ---
> > drivers/video/fbdev/ssd1307fb.c | 61 +++++++++++++++++++--------------
> > 1 file changed, 36 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> > index 6d7bd025bca1a175..cfa27ea0feab4f01 100644
> > --- a/drivers/video/fbdev/ssd1307fb.c
> > +++ b/drivers/video/fbdev/ssd1307fb.c
> > @@ -152,6 +152,38 @@ static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
> > return ret;
> > }
> >
> > +static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
> > + u8 cols, u8 page_start, u8 pages)
> > +{
> Bikeshedding, but I think a dedicated function for col_range and another
> for page_range had been simpler to read.
I agree.
Originally, before I removed the call during initialization, there were
two calls to this function, so it made sense to have a single function.
> With or wihout this change:
> Acked-by: Sam Ravnborg <[email protected]>
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
Hi Sam,
On Mon, Jul 19, 2021 at 9:21 PM Sam Ravnborg <[email protected]> wrote:
> On Wed, Jul 14, 2021 at 04:58:03PM +0200, Geert Uytterhoeven wrote:
> > 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 call to ssd1307fb_set_address_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 <[email protected]>
> > --- a/drivers/video/fbdev/ssd1307fb.c
> > +++ b/drivers/video/fbdev/ssd1307fb.c
> > @@ -184,16 +184,18 @@ static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
> > 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;
> > u8 *vmem = par->info->screen_buffer;
> > unsigned int line_length = par->info->fix.line_length;
> > - unsigned int pages = DIV_ROUND_UP(par->height, 8);
> > + unsigned int pages = DIV_ROUND_UP(height + y % 8, 8);
>
> Add () like this - at least it helps me:
> > + unsigned int pages = DIV_ROUND_UP((height + y) % 8, 8);
Thanks, that's actually a genuine bug.
> > @@ -226,13 +228,18 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
> > * (5) A4 B4 C4 D4 E4 F4 G4 H4
> > */
> >
> > - for (i = 0; i < pages; i++) {
> > + ret = ssd1307fb_set_address_range(par, par->col_offset + x, width,
> > + par->page_offset + y / 8, pages);
> > + if (ret < 0)
> > + goto out_free;
> > +
> > + for (i = y / 8; i < y / 8 + pages; i++) {
> > int m = 8;
> >
> > /* Last page may be partial */
> > - if (i + 1 == pages && par->height % 8)
> > + if (8 * (i + 1) > par->height)
> > m = par->height % 8;
> As before, this looks wrong to me.
Let's sort that out in the other thread...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
Hi Sam,
On Tue, Jul 20, 2021 at 9:56 AM Geert Uytterhoeven <[email protected]> wrote:
> On Mon, Jul 19, 2021 at 9:21 PM Sam Ravnborg <[email protected]> wrote:
> > On Wed, Jul 14, 2021 at 04:58:03PM +0200, Geert Uytterhoeven wrote:
> > > 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 call to ssd1307fb_set_address_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 <[email protected]>
>
> > > --- a/drivers/video/fbdev/ssd1307fb.c
> > > +++ b/drivers/video/fbdev/ssd1307fb.c
> > > @@ -184,16 +184,18 @@ static int ssd1307fb_set_address_range(struct ssd1307fb_par *par, u8 col_start,
> > > 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;
> > > u8 *vmem = par->info->screen_buffer;
> > > unsigned int line_length = par->info->fix.line_length;
> > > - unsigned int pages = DIV_ROUND_UP(par->height, 8);
> > > + unsigned int pages = DIV_ROUND_UP(height + y % 8, 8);
> >
> > Add () like this - at least it helps me:
> > > + unsigned int pages = DIV_ROUND_UP((height + y) % 8, 8);
>
> Thanks, that's actually a genuine bug.
No it's not "(height + y) % 8" is wrong.
Better if I reorder the operands like below?
unsigned int pages = DIV_ROUND_UP(y % 8 + height, 8);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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
On Thu, Jul 15, 2021 at 8:54 AM Geert Uytterhoeven <[email protected]> wrote:
>
> Hi Sam,
>
> On Wed, Jul 14, 2021 at 5:27 PM Sam Ravnborg <[email protected]> wrote:
> > On Wed, Jul 14, 2021 at 04:57:59PM +0200, Geert Uytterhoeven wrote:
> > > This patch series optimizes console operations on ssd1307fb, after the
> > > customary fixes and cleanups.
> >
> > What is required to to have a drm driver that could do the same?
>
> Add monochrome support to DRM?
I think the bits that are missing for that are
- wiring up the conversion from R* formats to their fbdev counterparts
in the emulation helper (if you want to support userspace sending the
native format directly through fbdev
Everything else is there and we have drivers doing this, e.g.
drm/tiny/repaper.c.
-Daniel
>
> > Note: I will take a look at the patches a bit later.
>
> TIA!
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
>
> 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
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch