Commit 97b9a5a2 authored by Ben Nizette's avatar Ben Nizette Committed by Linus Torvalds

atmel-lcdc: fix pixclock upper bound detection

AFAICT the code which checks that the requested pixclock value is within
bounds is incorrect.  It ensures that the lcdc core clock is at least
(bytes per pixel) times higher than the pixel clock rather than just
greater than or equal to.

There are tighter restrictions on the pixclock value as a function of bus
width for STN panels but even then it isn't a simple relationship as
currently checked for.  IMO either something like the below patch should
be applied or else more detailed checking logic should be implemented
which takes in to account the panel type as well.
Signed-off-by: default avatarBen Nizette <bn@niasdigital.com>
Acked-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Cc: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Cc: Daniel Glockner <dg@emlix.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4113819e
......@@ -345,7 +345,7 @@ static int atmel_lcdfb_check_var(struct fb_var_screeninfo *var,
dev_dbg(dev, " bpp: %u\n", var->bits_per_pixel);
dev_dbg(dev, " clk: %lu KHz\n", clk_value_khz);
if ((PICOS2KHZ(var->pixclock) * var->bits_per_pixel / 8) > clk_value_khz) {
if (PICOS2KHZ(var->pixclock) > clk_value_khz) {
dev_err(dev, "%lu KHz pixel clock is too fast\n", PICOS2KHZ(var->pixclock));
return -EINVAL;
}
......
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