diff options
| author | Simon Glass <sjg@chromium.org> | 2011-06-27 15:50:10 -0700 |
|---|---|---|
| committer | Simon Glass <sjg@chromium.org> | 2011-08-29 10:39:43 -0700 |
| commit | a68cdfe396cb533228d218bc2e0e1731482d69a1 (patch) | |
| tree | 59a6cdebfa8a46bf72faf2d2f0d316f983c24b4e /drivers | |
| parent | 1a242769afa9b529e46958547c855a4de93b2657 (diff) | |
Change LCD to use write-back cache
As expected write-through caching slows the LCD frame buffer to an
unacceptable degree. This change provides an option to use write-back, with
a dcache flush after each puts(), clear screen or scroll. This option
becomes the default unless overwritten in the fdt.
Timings (done with about 2 screenfuls of vboot debug output):
flushing dcache after each line
write-through cache:
Timer summary in microseconds:
Mark Elapsed Stage
0 0 awake
2,418,290 2,418,290 bootm_start
no cache logic (tearing!):
Timer summary in microseconds:
Mark Elapsed Stage
0 0 awake
1,434,217 1,434,217 bootm_start
This commit:
Timer summary in microseconds:
Mark Elapsed Stage
0 0 awake
1,500,866 1,500,866 bootm_start
BUG=chromium-os:17047
TEST=build and boot on Seaboard, check for LCD tearing.
Change-Id: I2155f9c4ad3b59376f1b713daed77cf5aac396a4
Reviewed-on: http://gerrit.chromium.org/gerrit/3313
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/video/tegra2.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/video/tegra2.c b/drivers/video/tegra2.c index 111a32623c..047c067063 100644 --- a/drivers/video/tegra2.c +++ b/drivers/video/tegra2.c @@ -184,7 +184,7 @@ static void update_panel_size(struct fdt_lcd *config) void lcd_ctrl_init(void *lcdbase) { struct fdt_lcd config; - int line_length; + int line_length, size; /* get panel details */ if (fdt_decode_lcd(gd->blob, &config)) { @@ -200,11 +200,19 @@ void lcd_ctrl_init(void *lcdbase) */ config.frame_buffer = (u32)lcd_base; update_panel_size(&config); + size = lcd_get_size(&line_length), /* call board specific hw init */ init_lcd(&config); - mmu_set_region_dcache(config.frame_buffer, - lcd_get_size(&line_length), DCACHE_WRITETHROUGH); + + /* For write-through or cache off, change the LCD memory region */ + if (!(config.cache_type & FDT_LCD_CACHE_WRITE_BACK)) + mmu_set_region_dcache(config.frame_buffer, size, + config.cache_type & FDT_LCD_CACHE_WRITE_THROUGH ? + DCACHE_WRITETHROUGH : DCACHE_OFF); + + /* Enable flushing after LCD writes if requested */ + lcd_set_flush_dcache(config.cache_type & FDT_LCD_CACHE_FLUSH); debug("LCD frame buffer at %p\n", lcd_base); } |