From 3cb4f25cc702db17455583599d0940c81337a17a Mon Sep 17 00:00:00 2001 From: Peng Fan Date: Wed, 9 Mar 2016 16:07:21 +0800 Subject: [PATCH] video: ipu: avoid overflow issue Multiplication, as "clk->parent->rate * 16" may overflow. So use do_div to avoid such issue. Signed-off-by: Peng Fan Signed-off-by: Sandor Yu Cc: Anatolij Gustschin Cc: Stefano Babic Cc: Fabio Estevam --- drivers/video/ipu_common.c | 73 ++++++++++++++++++++++++++++---------- 1 file changed, 54 insertions(+), 19 deletions(-) diff --git a/drivers/video/ipu_common.c b/drivers/video/ipu_common.c index 9f85102915..36d4b23bfe 100644 --- a/drivers/video/ipu_common.c +++ b/drivers/video/ipu_common.c @@ -19,6 +19,7 @@ #include #include #include +#include #include "ipu.h" #include "ipu_regs.h" @@ -275,50 +276,84 @@ static inline void ipu_ch_param_set_buffer(uint32_t ch, int bufNum, static void ipu_pixel_clk_recalc(struct clk *clk) { - u32 div = __raw_readl(DI_BS_CLKGEN0(clk->id)); - if (div == 0) - clk->rate = 0; - else - clk->rate = (clk->parent->rate * 16) / div; + u32 div; + u64 final_rate = (unsigned long long)clk->parent->rate * 16; + + div = __raw_readl(DI_BS_CLKGEN0(clk->id)); + debug("read BS_CLKGEN0 div:%d, final_rate:%lld, prate:%ld\n", + div, final_rate, clk->parent->rate); + + clk->rate = 0; + if (div != 0) { + do_div(final_rate, div); + clk->rate = final_rate; + } } static unsigned long ipu_pixel_clk_round_rate(struct clk *clk, unsigned long rate) { - u32 div, div1; - u32 tmp; + u64 div, final_rate; + u32 remainder; + u64 parent_rate = (unsigned long long)clk->parent->rate * 16; + /* * Calculate divider * Fractional part is 4 bits, * so simply multiply by 2^4 to get fractional part. */ - tmp = (clk->parent->rate * 16); - div = tmp / rate; - + div = parent_rate; + remainder = do_div(div, rate); + /* Round the divider value */ + if (remainder > (rate / 2)) + div++; if (div < 0x10) /* Min DI disp clock divider is 1 */ div = 0x10; if (div & ~0xFEF) div &= 0xFF8; else { - div1 = div & 0xFE0; - if ((tmp/div1 - tmp/div) < rate / 4) - div = div1; - else - div &= 0xFF8; + /* Round up divider if it gets us closer to desired pix clk */ + if ((div & 0xC) == 0xC) { + div += 0x10; + div &= ~0xF; + } } - return (clk->parent->rate * 16) / div; + final_rate = parent_rate; + do_div(final_rate, div); + + return final_rate; } static int ipu_pixel_clk_set_rate(struct clk *clk, unsigned long rate) { - u32 div = (clk->parent->rate * 16) / rate; + u64 div, parent_rate; + u32 remainder; + + parent_rate = (unsigned long long)clk->parent->rate * 16; + div = parent_rate; + remainder = do_div(div, rate); + /* Round the divider value */ + if (remainder > (rate / 2)) + div++; + + /* Round up divider if it gets us closer to desired pix clk */ + if ((div & 0xC) == 0xC) { + div += 0x10; + div &= ~0xF; + } + if (div > 0x1000) + debug("Overflow, DI_BS_CLKGEN0 div:0x%x\n", (u32)div); __raw_writel(div, DI_BS_CLKGEN0(clk->id)); - /* Setup pixel clock timing */ + /* + * Setup pixel clock timing + * Down time is half of period + */ __raw_writel((div / 16) << 16, DI_BS_CLKGEN1(clk->id)); - clk->rate = (clk->parent->rate * 16) / div; + clk->rate = (u64)(clk->parent->rate * 16) / div; + return 0; } -- 2.39.5