Re: [V2] tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which otherwise could return a sub-optimal clock rate.

[Vijaya Krishna Nivarthi]

On 7/6/2022 11:51 PM, Doug Anderson wrote:
> Hi,
>
> On Wed, Jul 6, 2022 at 10:44 AM Vijaya Krishna Nivarthi
> <quic_vnivarth@xxxxxxxxxxx> wrote:
> > Hi,
> >
> >
> > On 7/6/2022 8:56 PM, Doug Anderson wrote:
> > > Hi,
> > >
> > > On Mon, Jul 4, 2022 at 11:57 AM Vijaya Krishna Nivarthi (Temp)
> > > <vnivarth@xxxxxxxxxxxxxxxx> wrote:
> > > > Hi,
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Doug Anderson <dianders@xxxxxxxxxxxx>
> > > > > Sent: Friday, July 1, 2022 8:38 PM
> > > > > To: Vijaya Krishna Nivarthi (Temp) (QUIC) <quic_vnivarth@xxxxxxxxxxx>
> > > > > Cc: Andy Gross <agross@xxxxxxxxxx>; bjorn.andersson@xxxxxxxxxx; Konrad
> > > > > Dybcio <konrad.dybcio@xxxxxxxxxxxxxx>; Greg Kroah-Hartman
> > > > > <gregkh@xxxxxxxxxxxxxxxxxxx>; Jiri Slaby <jirislaby@xxxxxxxxxx>; linux-arm-
> > > > > msm <linux-arm-msm@xxxxxxxxxxxxxxx>; linux-serial@xxxxxxxxxxxxxxx; LKML
> > > > > <linux-kernel@xxxxxxxxxxxxxxx>; Mukesh Savaliya (QUIC)
> > > > > <quic_msavaliy@xxxxxxxxxxx>; Matthias Kaehlcke <mka@xxxxxxxxxxxx>;
> > > > > Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > > > > Subject: Re: [V2] tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which
> > > > > otherwise could return a sub-optimal clock rate.
> > > > >
> > > > > WARNING: This email originated from outside of Qualcomm. Please be wary
> > > > > of any links or attachments, and do not enable macros.
> > > > >
> > > > > Hi,
> > > > >
> > > > > On Fri, Jul 1, 2022 at 4:04 AM Vijaya Krishna Nivarthi (Temp) (QUIC)
> > > > > <quic_vnivarth@xxxxxxxxxxx> wrote:
> Ah, you are correct. So just:
>
> div = DIV_ROUND_UP(freq, desired_clk);
>
> ...because freq _has_ to be greater than mult. If it was < "mult -
> offset" we would have ended the loop. If it was between "mult -
> offset" and "mult + offset" (inclusive) then we would have success. So
> freq must be > "mult + offset" at the end of the loop.
>
> -Doug


Thank you, uploaded V3.