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authorPeng Fan <van.freenix@gmail.com>2016-03-09 16:07:21 +0800
committerAnatolij Gustschin <agust@denx.de>2016-03-14 22:47:41 +0100
commit3cb4f25cc702db17455583599d0940c81337a17a (patch)
treec8ae22e1b2687a89fd290b4a5da5db4408ecc03f /drivers/video
parentc87c30e3ba9ab110c031c14d1f349118d32041c1 (diff)
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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 <van.freenix@gmail.com> Signed-off-by: Sandor Yu <sandor.yu@nxp.com> Cc: Anatolij Gustschin <agust@denx.de> Cc: Stefano Babic <sbabic@denx.de> Cc: Fabio Estevam <fabio.estevam@nxp.com>
Diffstat (limited to 'drivers/video')
-rw-r--r--drivers/video/ipu_common.c73
1 files changed, 54 insertions, 19 deletions
diff --git a/drivers/video/ipu_common.c b/drivers/video/ipu_common.c
index 9f85102..36d4b23 100644
--- a/drivers/video/ipu_common.c
+++ b/drivers/video/ipu_common.c
@@ -19,6 +19,7 @@
#include <asm/errno.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/crm_regs.h>
+#include <div64.h>
#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;
}