| Message ID | 1452803219-16675-4-git-send-email-sjg@chromium.org |
|---|---|
| State | Accepted |
| Commit | 8d37483e7cfff9e36a928379d7ab6c4fc11bd4c1 |
| Delegated to: | Tom Warren |
| Headers | show |
On 01/14/2016 01:26 PM, Simon Glass wrote: > This seems to give the best performance, so let's use it always. I thought we chose the current cache mode due to display corruption issues with other modes, but I tested a change that I believe does the same as this change on Seaboard without any apparent issue so, Acked-by: Stephen Warren <swarren@nvidia.com>
On Mon, Jan 18, 2016 at 01:07:10PM -0700, Stephen Warren wrote: > On 01/14/2016 01:26 PM, Simon Glass wrote: > >This seems to give the best performance, so let's use it always. > > I thought we chose the current cache mode due to display corruption issues > with other modes, but I tested a change that I believe does the same as this > change on Seaboard without any apparent issue so, > > Acked-by: Stephen Warren <swarren@nvidia.com> I think for framebuffers the best option is still write-combine, which would be something like: DCACHE_WRITECOMBINE = DCACHE_OFF | TTB_SECT_B_MASK on ARM v7. Did you ever benchmark that against DCACHE_WRITETHROUGH? It should be faster provided that you never read from the region. Thierry
Hi Thierry, On 20 January 2016 at 07:53, Thierry Reding <thierry.reding@gmail.com> wrote: > On Mon, Jan 18, 2016 at 01:07:10PM -0700, Stephen Warren wrote: >> On 01/14/2016 01:26 PM, Simon Glass wrote: >> >This seems to give the best performance, so let's use it always. >> >> I thought we chose the current cache mode due to display corruption issues >> with other modes, but I tested a change that I believe does the same as this >> change on Seaboard without any apparent issue so, >> >> Acked-by: Stephen Warren <swarren@nvidia.com> > > I think for framebuffers the best option is still write-combine, which > would be something like: > > DCACHE_WRITECOMBINE = DCACHE_OFF | TTB_SECT_B_MASK > > on ARM v7. Did you ever benchmark that against DCACHE_WRITETHROUGH? It > should be faster provided that you never read from the region. This is noticeably slower in my experience. Reading from the region is pretty common - e.g. scrolling. Regards, Simon
diff --git a/drivers/video/tegra.c b/drivers/video/tegra.c index d34189d..cb2a157 100644 --- a/drivers/video/tegra.c +++ b/drivers/video/tegra.c @@ -22,15 +22,6 @@ DECLARE_GLOBAL_DATA_PTR; -enum lcd_cache_t { - FDT_LCD_CACHE_OFF = 0, - FDT_LCD_CACHE_WRITE_THROUGH = 1 << 0, - FDT_LCD_CACHE_WRITE_BACK = 1 << 1, - FDT_LCD_CACHE_FLUSH = 1 << 2, - FDT_LCD_CACHE_WRITE_BACK_FLUSH = FDT_LCD_CACHE_WRITE_BACK | - FDT_LCD_CACHE_FLUSH, -}; - /* Information about the display controller */ struct tegra_lcd_priv { int width; /* width in pixels */ @@ -41,7 +32,6 @@ struct tegra_lcd_priv { struct disp_ctlr *disp; /* Display controller to use */ fdt_addr_t frame_buffer; /* Address of frame buffer */ unsigned pixel_clock; /* Pixel clock in Hz */ - enum lcd_cache_t cache_type; }; enum { @@ -310,7 +300,6 @@ static int tegra_lcd_probe(struct udevice *dev) struct video_priv *uc_priv = dev_get_uclass_priv(dev); struct tegra_lcd_priv *priv = dev_get_priv(dev); const void *blob = gd->fdt_blob; - int type = DCACHE_OFF; int ret; /* Initialize the Tegra display controller */ @@ -330,15 +319,11 @@ static int tegra_lcd_probe(struct udevice *dev) return ret; } - /* Set up the LCD caching as requested */ - if (priv->cache_type & FDT_LCD_CACHE_WRITE_THROUGH) - type = DCACHE_WRITETHROUGH; - else if (priv->cache_type & FDT_LCD_CACHE_WRITE_BACK) - type = DCACHE_WRITEBACK; - mmu_set_region_dcache_behaviour(priv->frame_buffer, plat->size, type); + mmu_set_region_dcache_behaviour(priv->frame_buffer, plat->size, + DCACHE_WRITETHROUGH); /* Enable flushing after LCD writes if requested */ - video_set_flush_dcache(dev, priv->cache_type & FDT_LCD_CACHE_FLUSH); + video_set_flush_dcache(dev, true); uc_priv->xsize = priv->width; uc_priv->ysize = priv->height;
This seems to give the best performance, so let's use it always. Signed-off-by: Simon Glass <sjg@chromium.org> --- drivers/video/tegra.c | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-)