[v5 2/2] pwm: Add Aspeed ast2600 PWM support
Billy Tsai
billy_tsai at aspeedtech.com
Mon May 17 12:53:44 AEST 2021
Hello,
On 2021/5/15, 11:57 PM,Uwe Kleine-Königwrote:
> > + div_h = DIV_ROUND_DOWN_ULL(div_h,
> > + (FIELD_MAX(PWM_ASPEED_CTRL_CLK_DIV_L) + 1));
> > + div_h = DIV_ROUND_DOWN_ULL(div_h, NSEC_PER_SEC);
> As a division is an expensive operation you can better first multiply
> NSEC_PER_SEC and FIELD_MAX(PWM_ASPEED_CTRL_CLK_DIV_L) + 1 and divide by
> the result.
When I multiply NSEC_PER_SEC and FIELD_MAX(PWM_ASPEED_CTRL_CLK_DIV_L) + 1 the result will overflow
for 32-bits and the divisor type of do_div is 32-bits so I need to do div twice to avoid the issue.
Can you give me some suggests?
Thanks
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