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Sat, 11 Jul 2026 15:51:37 -0700 (PDT) X-Received: by 2002:a17:903:3c0c:b0:2c9:e69f:edce with SMTP id d9443c01a7336-2ce9f39973bmr40429195ad.44.1783810296625; Sat, 11 Jul 2026 15:51:36 -0700 (PDT) Received: from jic23-huawei ([50.35.46.84]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ccc9d59e33sm76365505ad.74.2026.07.11.15.51.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 11 Jul 2026 15:51:36 -0700 (PDT) Date: Sat, 11 Jul 2026 23:51:32 +0100 From: Jonathan Cameron To: Jean-Baptiste Maneyrol Cc: Jean-Baptiste Maneyrol via B4 Relay , David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , "linux-iio@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH] iio: imu: inv_icm42600: fix timestamp clock period by using lower value Message-ID: <20260711235132.1568bd75@jic23-huawei> In-Reply-To: References: <20260623-inv-icm42600-fix-timestamp-clock-period-v1-1-82184d2429f4@tdk.com> <20260703200224.69d60475@jic23-huawei> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Spam-Info: AW1haW4tMjYwNzExMDIzMyBTYWx0ZWRfX+g6/zg45ht9h RwQRbZKh49BrpfA1chZe16H8dN+2e30eNV6hiZ/Pr/0v+rOvMeCV+t6f/anKlAiIer8AMhAVirP L8nPHMq+MUk4ezJG/bNflfH6Kn8c9sE= X-Proofpoint-GUID: 3g_axelRTivapKXk308duaDNNyySvFL4 X-Proofpoint-ORIG-GUID: 3g_axelRTivapKXk308duaDNNyySvFL4 X-Authority-Analysis: v=2.4 cv=dJSWXuZb c=1 sm=1 tr=0 ts=6a52c8fa cx=c_pps a=cmESyDAEBpBGqyK7t0alAg==:117 a=qC1CW/w66vtJz1P9yTJxNA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=In8RU02eAAAA:8 a=VwQbUJbxAAAA:8 a=tpoKPDdqsMjE0q__xjQA:9 a=QEXdDO2ut3YA:10 a=1OuFwYUASf3TG4hYMiVC:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzExMDIzMyBTYWx0ZWRfX9Z4hKnPuE3mX wK9C80tbDZgqSM427HZcLPaMw9NL4ppQgkKw1+WXPDcvDN/UG+CCR90hsFNbLcPzKyJmK6Y8y1A zHfudETO/y3nAno5lP1wpYvhzGdZYzxOmhtDjYrbPoAR/wFQN8UEgWv1evvWq6tIFpVPKdtSDL9 DQjMIx3q4wrq5vZxz7RaOvTrWCrxhFS0fDpWX9v3QGAlyZj41lcjx5ZlyC04nkUWnux3Yc1ByDM s2bE+RF58STfZLpFEU6kUhGYYvmgEh9X9wxcqkAO97WtAXuQVaUblNlajcMnpoaD5idJBcoApqS g/397N15Cx9xanXgjZFOAG/+fcVf3E9PAeNpfPKeO58ImwomSnndx/yO77TlyFlg/f3v2/9ZL2d OdppIQCsynGXQab+UP/dJ5MzsQu2ZNd19dDMWxUyUAa9CFjpZGAkBGy6RNKJrKiNva8vLZt1vr5 TQEjamT4VGGD5vocVQQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-11_06,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 suspectscore=0 phishscore=0 clxscore=1015 spamscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607110233 On Mon, 6 Jul 2026 08:00:43 +0000 Jean-Baptiste Maneyrol wrote: > >From: Jonathan Cameron > >Sent: Friday, July 3, 2026 21:02 > >To: Jean-Baptiste Maneyrol via B4 Relay > >Cc: Jean-Baptiste Maneyrol; David Lechner; Nuno S=C3=A1; Andy Shevchenko= ; linux-iio@vger.kernel.org; linux-kernel@vger.kernel.org; stable@vger.kern= el.org > >Subject: Re: [PATCH] iio: imu: inv_icm42600: fix timestamp clock period = by using lower value > > > >On Tue, 23 Jun 2026 16:=E2=80=8A22:=E2=80=8A15 +0200 Jean-Baptiste Maney= rol via B4 Relay wrote: > From: Jean-Baptiste Maneyr= ol > Sorry for = delay - I'm finally > >ZjQcmQRYFpfptBannerStart > >This Message Is From an External Sender > >This message came from outside your organization. > > > >ZjQcmQRYFpfptBannerEnd > > > >On Tue, 23 Jun 2026 16:22:15 +0200 > >Jean-Baptiste Maneyrol via B4 Relay wrote: > > =20 > >> From: Jean-Baptiste Maneyrol > >> =20 > >Sorry for delay - I'm finally getting back on top of my emails (for IIO = anyway!) > > =20 > >> Clock period value is used for computing periods of sampling. There is > >> no need for it to be higher than the maximum odr, otherwise we are > >> losing precision in the computation for nothing. =20 > > > >Silly question - what are the user visible results of that precision los= s? > > > >Less accurate time stamp estimates, or something else? > > > >Jonathan > > =20 > Hello Jonathan, >=20 > that's not a silly question, it will effectively lead to less accurate ti= mestamps. >=20 > We are measuring the delta time between 2 interrupts, and for abstracting= the ODR > we divide this measurement to go to the configured clock period. Then we = compute timestamps by multiplying back this measured clock period. If we di= vide > too much, we are losing precision. Since maximum ODR is 8kHz, there is no > need to go further than this value. Internal chip clock is 32kHz, but max= imum > ODR is 8kHz. >=20 Seems I applied this and forgot to say so. Anyhow, now upstream. Jonathan > Thanks, > JB >=20 > > =20 > >> > >> Switch clock period value to maximum odr period (8kHz). > >> > >> Fixes: 0ecc363ccea7 ("iio: make invensense timestamp module generic") > >> Cc: stable@vger.kernel.org > >> Signed-off-by: Jean-Baptiste Maneyrol = =20 > > > > =20 > >> --- > >> drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c | 4 ++-- > >> drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c | 4 ++-- > >> 2 files changed, 4 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c b/drive= rs/iio/imu/inv_icm42600/inv_icm42600_accel.c > >> index 532d5fdffaf8..7df920ef3cf0 100644 > >> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c > >> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c > >> @@ -1170,10 +1170,10 @@ struct iio_dev *inv_icm42600_accel_init(struct= inv_icm42600_state *st) > >> accel_st->filter =3D INV_ICM42600_FILTER_AVG_16X; > >> > >> /* > >> - * clock period is 32kHz (31250ns) > >> + * clock period is 8kHz (125000ns) > >> * jitter is +/- 2% (20 per mille) > >> */ > >> - ts_chip.clock_period =3D 31250; > >> + ts_chip.clock_period =3D 125000; > >> ts_chip.jitter =3D 20; > >> ts_chip.init_period =3D inv_icm42600_odr_to_period(st->conf.acce= l.odr); > >> inv_sensors_timestamp_init(&accel_st->ts, &ts_chip); > >> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c b/driver= s/iio/imu/inv_icm42600/inv_icm42600_gyro.c > >> index 11339ddf1da3..a18dcac93929 100644 > >> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c > >> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c > >> @@ -755,10 +755,10 @@ struct iio_dev *inv_icm42600_gyro_init(struct in= v_icm42600_state *st) > >> } > >> > >> /* > >> - * clock period is 32kHz (31250ns) > >> + * clock period is 8kHz (125000ns) > >> * jitter is +/- 2% (20 per mille) > >> */ > >> - ts_chip.clock_period =3D 31250; > >> + ts_chip.clock_period =3D 125000; > >> ts_chip.jitter =3D 20; > >> ts_chip.init_period =3D inv_icm42600_odr_to_period(st->conf.acce= l.odr); > >> inv_sensors_timestamp_init(&gyro_st->ts, &ts_chip); > >> > >> --- > >> base-commit: cc746297b23e89bd5df9f91f3a0ca209e8991763 > >> change-id: 20260623-inv-icm42600-fix-timestamp-clock-period-931338a848= c3 > >> > >> Best regards, > >> -- > >> Jean-Baptiste Maneyrol > >> > > =20