On Wed, 15 Oct 2014 12:10:45 +0200 Hans de Goede <[email protected]> wrote:
> Before the u-boot dram cleanup u-boot would always set PLL5 factor m to > 2 (reg value 1) and div p to 1, and get_cmu_clk in the nand code > would calculate the pll5p clk like this: > > clk = 24 * factor_n * factor_k / div_p / factor_m; > > aka: > > clk = 24 * factor_n * factor_k / (div_p * factor_m); > > This is wrong however, factor_m is not used to calculate pll5p, and div_p is > not a straight divider, but it divides by 2 ^ div_p. Since with the m == 2 and > p == 1 settings used before the dram cleanup, this happend to do the right > thing in the form of dividing by 2. But with the new dram code div_p is 0, > and then the old get_cmu_clk code fails with a divide by 0 error. > > This commit fixes this, by changing the clk calculation to the correct form > of: > > clk = (24 * factor_n * factor_k) >> div_p; > > Signed-off-by: Hans de Goede <[email protected]> > --- > drivers/block/sunxi_nand/nfd/nand_blk.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/block/sunxi_nand/nfd/nand_blk.c > b/drivers/block/sunxi_nand/nfd/nand_blk.c > index a632453..2169301 100644 > --- a/drivers/block/sunxi_nand/nfd/nand_blk.c > +++ b/drivers/block/sunxi_nand/nfd/nand_blk.c > @@ -1095,16 +1095,15 @@ __u32 get_cmu_clk(void) > { > __u32 reg_val; > __u32 div_p, factor_n; > - __u32 factor_k, factor_m; > + __u32 factor_k; > __u32 clock; > > reg_val = *(volatile unsigned int *)(0xf1c20000 + 0x20); > div_p = (reg_val >> 16) & 0x3; > factor_n = (reg_val >> 8) & 0x1f; > factor_k = ((reg_val >> 4) & 0x3) + 1; > - factor_m = ((reg_val >> 0) & 0x3) + 1; > > - clock = 24 * factor_n * factor_k/div_p/factor_m; > + clock = (24 * factor_n * factor_k) >> div_p; > > return clock; > } That's a good catch. Also one more copy-paste of exactly the same code appears to be in 'drivers/block/sunxi_nand/nandtest/nand_test.c' -- Best regards, Siarhei Siamashka -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
