On 07/18/2012 03:33 PM, Manjunathappa, Prakash wrote: > Patch works around the below silicon errata: > During LCDC initialization, there is the potential for a FIFO > underflow condition to occur. A FIFO underflow condition > occurs when the input FIFO is completely empty and the LCDC > raster controller logic that drives data to the output pins > attempts to fetch data from the FIFO. When a FIFO underflow > condition occurs, incorrect data will be driven out on the > LCDC data pins. > > Software should poll the FUF bit field in the LCD_STAT register > to check if an error condition has occurred or service the > interrupt if FUF_EN is enabled when FUF occurs. If the FUF bit > field has been set to 1, this will indicate an underflow > condition has occurred and then the software should execute a > reset of the LCDC via the LPSC. > > This problem may occur if the LCDC FIFO threshold size > (LCDDMA_CTRL[TH_FIFO_READY]) is left at its default value after > reset. Increasing the FIFO threshold size will reduce or > eliminate underflows. Setting the threshold size to 256 double > words or larger is recommended. > > Above issue is described in section 2.1.3 of silicon errata > http://www.ti.com/lit/er/sprz313e/sprz313e.pdf > > Signed-off-by: Rajashekhara, Sudhakar <sudhakar.raj@xxxxxx> > Signed-off-by: Manjunathappa, Prakash <prakash.pm@xxxxxx> Applied both patches of this series. Thanks, Florian Tobias Schandinat > --- > Seems like version 1 of this patch did not reach fbdev mailing list. > Since v1: > Removed clk_disable/clk_enable from error interrupt handling code. > > drivers/video/da8xx-fb.c | 11 +++++++---- > include/video/da8xx-fb.h | 3 +++ > 2 files changed, 10 insertions(+), 4 deletions(-) > > diff --git a/drivers/video/da8xx-fb.c b/drivers/video/da8xx-fb.c > index 183366d..186ab5a 100644 > --- a/drivers/video/da8xx-fb.c > +++ b/drivers/video/da8xx-fb.c > @@ -353,8 +353,8 @@ static void lcd_blit(int load_mode, struct da8xx_fb_par *par) > lcd_enable_raster(); > } > > -/* Configure the Burst Size of DMA */ > -static int lcd_cfg_dma(int burst_size) > +/* Configure the Burst Size and fifo threhold of DMA */ > +static int lcd_cfg_dma(int burst_size, int fifo_th) > { > u32 reg; > > @@ -378,6 +378,9 @@ static int lcd_cfg_dma(int burst_size) > default: > return -EINVAL; > } > + > + reg |= (fifo_th << 8); > + > lcdc_write(reg, LCD_DMA_CTRL_REG); > > return 0; > @@ -679,8 +682,8 @@ static int lcd_init(struct da8xx_fb_par *par, const struct lcd_ctrl_config *cfg, > lcdc_write((lcdc_read(LCD_RASTER_TIMING_2_REG) & > ~LCD_INVERT_PIXEL_CLOCK), LCD_RASTER_TIMING_2_REG); > > - /* Configure the DMA burst size. */ > - ret = lcd_cfg_dma(cfg->dma_burst_sz); > + /* Configure the DMA burst size and fifo threshold. */ > + ret = lcd_cfg_dma(cfg->dma_burst_sz, cfg->fifo_th); > if (ret < 0) > return ret; > > diff --git a/include/video/da8xx-fb.h b/include/video/da8xx-fb.h > index 89d43b3..5a0e4f9 100644 > --- a/include/video/da8xx-fb.h > +++ b/include/video/da8xx-fb.h > @@ -82,6 +82,9 @@ struct lcd_ctrl_config { > > /* Raster Data Order Select: 1=Most-to-least 0=Least-to-most */ > unsigned char raster_order; > + > + /* DMA FIFO threshold */ > + int fifo_th; > }; > > struct lcd_sync_arg { -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
