If the device-tree specifies a max-memory-bandwidth property then the CLCD driver uses that to calculate the bits-per-pixel supported, however, it doesn't ensure that the result is a sane value, i.e. a power of 2 and <= 32 as the rest of the code assumes.
Acked-by: Pawel Moll <[email protected]> Signed-off-by: Jon Medhurst <[email protected]> --- This fixes code which is new in 3.17 (commit d10715be03) and so I assume is a candidate for adding to a coming -rc ? Without the fix, people can be left (as I was) with a blank non-functioning screen even if they create a valid device-tree for the new driver functionality. drivers/video/fbdev/amba-clcd.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/video/fbdev/amba-clcd.c b/drivers/video/fbdev/amba-clcd.c index beadd3e..98b66b7 100644 --- a/drivers/video/fbdev/amba-clcd.c +++ b/drivers/video/fbdev/amba-clcd.c @@ -24,6 +24,7 @@ #include <linux/list.h> #include <linux/amba/bus.h> #include <linux/amba/clcd.h> +#include <linux/bitops.h> #include <linux/clk.h> #include <linux/hardirq.h> #include <linux/dma-mapping.h> @@ -650,6 +651,7 @@ static int clcdfb_of_init_display(struct clcd_fb *fb) { struct device_node *endpoint; int err; + int bpp; u32 max_bandwidth; u32 tft_r0b0g0[3]; @@ -667,11 +669,15 @@ static int clcdfb_of_init_display(struct clcd_fb *fb) err = of_property_read_u32(fb->dev->dev.of_node, "max-memory-bandwidth", &max_bandwidth); - if (!err) - fb->panel->bpp = 8 * max_bandwidth / (fb->panel->mode.xres * + if (!err) { + bpp = 8 * max_bandwidth / (fb->panel->mode.xres * fb->panel->mode.yres * fb->panel->mode.refresh); - else - fb->panel->bpp = 32; + bpp = rounddown_pow_of_two(bpp); + if (bpp > 32) + bpp = 32; + } else + bpp = 32; + fb->panel->bpp = bpp; #ifdef CONFIG_CPU_BIG_ENDIAN fb->panel->cntl |= CNTL_BEBO; -- 2.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
