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video: ipufb: Allow to disable fractional pixelclock divider 

The IPU has a fractional pixelclock divider. When used, this produces
clock jitter which especially LVDS transceivers can't handle. Allow
to disable it via platform_data.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Sascha Hauer 2013-12-12 16:34:14 +01:00
parent 53bbcf85aa
commit 4e64bcac45
2 changed files with 14 additions and 2 deletions
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5
arch/arm/mach-imx/include/mach/imx-ipu-fb.h
View File

@ -47,6 +47,11 @@ struct imx_ipu_fb_platform_data {
void __iomem *framebuffer_ovl;
/** hook to enable backlight and stuff */
void (*enable)(int enable);
/*
* Fractional pixelclock divider causes jitter which some displays
* or LVDS transceivers can't handle. Disable it if necessary.
*/
int disable_fractional_divider;
};
#endif /* __MACH_IMX_IPU_FB_H__ */

11
drivers/video/imx-ipu-fb.c
View File

@ -43,6 +43,7 @@ struct ipu_fb_info {
struct device_d *dev;
unsigned int alpha;
int disable_fractional_divider;
};
/* IPU DMA Controller channel definitions. */
@ -409,7 +410,7 @@ static int sdc_init_panel(struct fb_info *info, enum disp_data_mapping fmt)
struct fb_videomode *mode = info->mode;
u32 reg, old_conf, div;
enum ipu_panel panel = IPU_PANEL_TFT;
unsigned long pixel_clk;
unsigned long pixel_clk, rate;
/* Init panel size and blanking periods */
reg = ((mode->hsync_len - 1) << 26) |
@ -466,7 +467,12 @@ static int sdc_init_panel(struct fb_info *info, enum disp_data_mapping fmt)
* i.MX31 it (HSP_CLK) is <= 178MHz. Currently 128.267MHz
*/
pixel_clk = PICOS2KHZ(mode->pixclock) * 1000UL;
div = clk_get_rate(fbi->clk) * 16 / pixel_clk;
rate = clk_get_rate(fbi->clk);
if (fbi->disable_fractional_divider)
div = DIV_ROUND_CLOSEST(rate, pixel_clk) * 16;
else
div = rate * 16 / pixel_clk;
if (div < 0x40) { /* Divider less than 4 */
dev_dbg(&info->dev,
@ -1000,6 +1006,7 @@ static int imxfb_probe(struct device_d *dev)
fbi->dev = dev;
fbi->enable = pdata->enable;
fbi->disp_data_fmt = pdata->disp_data_fmt;
fbi->disable_fractional_divider = pdata->disable_fractional_divider;
info->priv = fbi;
info->fbops = &imxfb_ops;
info->num_modes = pdata->num_modes;