Hi,
On Tue, Jun 21, 2022 at 10:58 AM Vijaya Krishna Nivarthi (Temp)
<vnivarth@xxxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> For desired_clk = 100 and clock rates like 1st from below, DIV_ROUND_UP seems to cause missing candidate solutions.
>
> static unsigned long clk_round_rate_test(struct clk *clk, unsigned long in_freq)
> {
> //unsigned long root_freq[] = {301, 702, 1004};
> //unsigned long root_freq[] = {301, 702, 1004, 2000, 3000};
> //unsigned long root_freq[] = {50, 97, 99};
> //unsigned long root_freq[] = {50, 97, 99, 200};
> //unsigned long root_freq[] = {92, 110, 193, 230};
> //unsigned long root_freq[] = {92, 110, 193, 230, 300, 401};
> //unsigned long root_freq[] = {92, 110, 193, 230, 295, 296, 297, 401};
> //unsigned long root_freq[] = {92, 110, 193, 230, 295, 296, 297, 300, 401};
> //unsigned long root_freq[] = {197, 198, 199};
> unsigned long root_freq[] = {197, 198, 199, 200};
> int i;
> size_t n = sizeof root_freq / sizeof *root_freq;
>
> for (i = 0; i < n; i++) {
> if (root_freq[i] >= in_freq)
> return root_freq[i];
> }
> return root_freq[n-1];
> }
>
> I modified to handle such cases, optimised little and uploaded a patch.
> It seems to work for all the cases like above.
I think it would have been simpler to just change this little section:
/* Save the first (lowest freq) within 2% */
actual_mult = DIV_ROUND_CLOSEST(freq, desired_clk) * desired_clk;
if (!ser_clk && freq <= actual_mult + two_percent) {
ser_clk = freq;
*clk_div = div;
}
That was the only bug, right? Then you could keep the DIV_ROUND_UP() solution?
-Doug
