On Thu, Mar 25, 2021 at 03:23:07AM -0700, Guenter Roeck wrote: > On Tue, Mar 23, 2021 at 04:02:29PM +0800, Yangbo Lu wrote: > > Current calculation for diff of TMR_ADD register value may have > > 64-bit overflow in this code line, when long type scaled_ppm is > > large. > > > > adj *= scaled_ppm; > > > > This patch is to resolve it by using mul_u64_u64_div_u64(). > > > > Signed-off-by: Yangbo Lu <yangbo...@nxp.com> > > Acked-by: Richard Cochran <richardcoch...@gmail.com> > > --- > > drivers/ptp/ptp_qoriq.c | 13 +++++++------ > > 1 file changed, 7 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c > > index 68beb1bd07c0..f7f220700cb5 100644 > > --- a/drivers/ptp/ptp_qoriq.c > > +++ b/drivers/ptp/ptp_qoriq.c > > @@ -189,15 +189,16 @@ int ptp_qoriq_adjfine(struct ptp_clock_info *ptp, > > long scaled_ppm) > > tmr_add = ptp_qoriq->tmr_add; > > adj = tmr_add; > > > > - /* calculate diff as adj*(scaled_ppm/65536)/1000000 > > - * and round() to the nearest integer > > + /* > > + * Calculate diff and round() to the nearest integer > > + * > > + * diff = adj * (ppb / 1000000000) > > + * = adj * scaled_ppm / 65536000000 > > */ > > - adj *= scaled_ppm; > > - diff = div_u64(adj, 8000000); > > - diff = (diff >> 13) + ((diff >> 12) & 1); > > + diff = mul_u64_u64_div_u64(adj, scaled_ppm, 32768000000); > > mul_u64_u64_div_u64() is not exported. As result, every build with > CONFIG_PTP_1588_CLOCK_QORIQ=m (ie every allmodconfig build) fails with: > > ERROR: modpost: "mul_u64_u64_div_u64" [drivers/ptp/ptp-qoriq.ko] undefined! > > or a similar error. > Ah, never mind. I see this is fixed in mainline (export added). I see the problem in pending-fixes and in next-20210325.
Sorry for the noise. Guenter
