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From:   "Vijaya Krishna Nivarthi (Temp) (QUIC)" <quic_vnivarth@quicinc.com>
To:     Greg KH <gregkh@linuxfoundation.org>,
        "Vijaya Krishna Nivarthi (Temp) (QUIC)" <quic_vnivarth@quicinc.com>
CC:     "agross@kernel.org" <agross@kernel.org>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "konrad.dybcio@somainline.org" <konrad.dybcio@somainline.org>,
        "jirislaby@kernel.org" <jirislaby@kernel.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Mukesh Savaliya (QUIC)" <quic_msavaliy@quicinc.com>,
        "dianders@chromium.org" <dianders@chromium.org>,
        "mka@chromium.org" <mka@chromium.org>,
        "swboyd@chromium.org" <swboyd@chromium.org>
Subject: RE: [V2] tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which
 otherwise could return a sub-optimal clock rate.
Thread-Topic: [V2] tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which
 otherwise could return a sub-optimal clock rate.
Thread-Index: AQHYi58pVIc+cNioKEmeVrCYMiTPqq1oDR+AgAAlBxA=
Date:   Thu, 30 Jun 2022 17:19:09 +0000
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References: <1656496841-5853-1-git-send-email-quic_vnivarth@quicinc.com>
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> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Thursday, June 30, 2022 8:31 PM
> To: Vijaya Krishna Nivarthi (Temp) (QUIC) <quic_vnivarth@quicinc.com>
> Cc: agross@kernel.org; bjorn.andersson@linaro.org;
> konrad.dybcio@somainline.org; jirislaby@kernel.org; linux-arm-
> msm@vger.kernel.org; linux-serial@vger.kernel.org; linux-
> kernel@vger.kernel.org; Mukesh Savaliya (QUIC)
> <quic_msavaliy@quicinc.com>; dianders@chromium.org;
> mka@chromium.org; swboyd@chromium.org
> Subject: Re: [V2] tty: serial: qcom-geni-serial: Fix get_clk_div_rate() w=
hich
> otherwise could return a sub-optimal clock rate.
>=20
> WARNING: This email originated from outside of Qualcomm. Please be wary
> of any links or attachments, and do not enable macros.
>=20
> On Wed, Jun 29, 2022 at 03:30:41PM +0530, Vijaya Krishna Nivarthi wrote:
> > In the logic around call to clk_round_rate(), for some corner
> > conditions,
> > get_clk_div_rate() could return an sub-optimal clock rate. Also, if an
> > exact clock rate was not found lowest clock was being returned.
> >
> > Search for suitable clock rate in 2 steps
> > a) exact match or within 2% tolerance
> > b) within 5% tolerance
> > This also takes care of corner conditions.
> >
> > Reported-by: kernel test robot <lkp@intel.com>
>=20
> Did the test robot really report the original issue, or just the v2 chang=
e?
>=20
> thanks,
>=20
> greg k-h

Test robot raised error for v1 patch and (I think) it got addressed in v2 w=
ith call to div_u64.
V2 doesn't have this error but other warnings which I am addressing along w=
ith other feedback.
Below is the error raised for v1.
Thank you,
Vijay/


All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: arm-linux-gnueabi-ld: DWARF error: could not find =
abbrev number 121
   drivers/tty/serial/qcom_geni_serial.o: in function `find_clk_rate_in_tol=
':
>> qcom_geni_serial.c:(.text+0x764): undefined reference to `__aeabi_uldivm=
od'