| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <7be63d9ed78848cb1ee43edae0d97720641daf44.camel@gmail.com> Date: Fri, 24 May 2024 12:59:12 +0200 From: Nuno Sá <noname.nuno@...il.com> To: Ramona Gradinariu <ramona.bolboaca13@...il.com>, linux-kernel@...r.kernel.org, jic23@...nel.org, linux-iio@...r.kernel.org, devicetree@...r.kernel.org, conor+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, robh@...nel.org, nuno.sa@...log.com Subject: Re: [PATCH v4 06/10] drivers: iio: imu: adis16475: generic computation for sample rate On Fri, 2024-05-24 at 12:00 +0300, Ramona Gradinariu wrote: > Currently adis16475 supports a sample rate between 1900 and 2100 Hz. > This patch changes the setting of sample rate from hardcoded values to > a generic computation based on the internal clock frequency. > This is a preparatory patch for adding support for adis1657x family > devices which allow sample rates between 3900 and 4100 Hz. > > Signed-off-by: Ramona Gradinariu <ramona.bolboaca13@...il.com> > --- Reviewed-by: Nuno Sa <nuno.sa@...log.com> > no changes in v4 > drivers/iio/imu/adis16475.c | 39 +++++++++++++++++++++---------------- > 1 file changed, 22 insertions(+), 17 deletions(-) > > diff --git a/drivers/iio/imu/adis16475.c b/drivers/iio/imu/adis16475.c > index ab955efdad92..c589f214259b 100644 > --- a/drivers/iio/imu/adis16475.c > +++ b/drivers/iio/imu/adis16475.c > @@ -310,6 +310,9 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 > freq) > u16 dec; > int ret; > u32 sample_rate = st->clk_freq; > + /* The optimal sample rate for the supported IMUs is between int_clk - 100 > and int_clk + 100. */ > + u32 max_sample_rate = st->info->int_clk * 1000 + 100000; > + u32 min_sample_rate = st->info->int_clk * 1000 - 100000; > > if (!freq) > return -EINVAL; > @@ -317,8 +320,9 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 > freq) > adis_dev_lock(&st->adis); > /* > * When using sync scaled mode, the input clock needs to be scaled so that > we have > - * an IMU sample rate between (optimally) 1900 and 2100. After this, we > can use the > - * decimation filter to lower the sampling rate in order to get what the > user wants. > + * an IMU sample rate between (optimally) int_clk - 100 and int_clk + 100. > + * After this, we can use the decimation filter to lower the sampling rate > in order > + * to get what the user wants. > * Optimally, the user sample rate is a multiple of both the IMU sample > rate and > * the input clock. Hence, calculating the sync_scale dynamically gives us > better > * chances of achieving a perfect/integer value for DEC_RATE. The math > here is: > @@ -336,23 +340,24 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 > freq) > * solution. In this case, we get the highest multiple of the > input clock > * lower than the IMU max sample rate. > */ > - if (scaled_rate > 2100000) > - scaled_rate = 2100000 / st->clk_freq * st->clk_freq; > + if (scaled_rate > max_sample_rate) > + scaled_rate = max_sample_rate / st->clk_freq * st- > >clk_freq; > else > - scaled_rate = 2100000 / scaled_rate * scaled_rate; > + scaled_rate = max_sample_rate / scaled_rate * scaled_rate; > > /* > * This is not an hard requirement but it's not advised to run the > IMU > - * with a sample rate lower than 1900Hz due to possible > undersampling > - * issues. However, there are users that might really want to take > the risk. > - * Hence, we provide a module parameter for them. If set, we allow > sample > - * rates lower than 1.9KHz. By default, we won't allow this and we > just roundup > - * the rate to the next multiple of the input clock bigger than > 1.9KHz. This > - * is done like this as in some cases (when DEC_RATE is 0) might > give > - * us the closest value to the one desired by the user... > + * with a sample rate lower than internal clock frequency, due to > possible > + * undersampling issues. However, there are users that might > really want > + * to take the risk. Hence, we provide a module parameter for > them. If set, > + * we allow sample rates lower than internal clock frequency. > + * By default, we won't allow this and we just roundup the rate to > the next > + * multiple of the input clock. This is done like this as in some > cases > + * (when DEC_RATE is 0) might give us the closest value to the one > desired > + * by the user... > */ > - if (scaled_rate < 1900000 && !low_rate_allow) > - scaled_rate = roundup(1900000, st->clk_freq); > + if (scaled_rate < min_sample_rate && !low_rate_allow) > + scaled_rate = roundup(min_sample_rate, st->clk_freq); > > sync_scale = scaled_rate / st->clk_freq; > ret = __adis_write_reg_16(&st->adis, ADIS16475_REG_UP_SCALE, > sync_scale); > @@ -1359,6 +1364,7 @@ static int adis16475_config_sync_mode(struct adis16475 *st) > struct device *dev = &st->adis.spi->dev; > const struct adis16475_sync *sync; > u32 sync_mode; > + u16 max_sample_rate = st->info->int_clk + 100; > > /* default to internal clk */ > st->clk_freq = st->info->int_clk * 1000; > @@ -1398,10 +1404,9 @@ static int adis16475_config_sync_mode(struct adis16475 *st) > /* > * In sync scaled mode, the IMU sample rate is the > clk_freq * sync_scale. > * Hence, default the IMU sample rate to the highest > multiple of the input > - * clock lower than the IMU max sample rate. The optimal > range is > - * 1900-2100 sps... > + * clock lower than the IMU max sample rate. > */ > - up_scale = 2100 / st->clk_freq; > + up_scale = max_sample_rate / st->clk_freq; > > ret = __adis_write_reg_16(&st->adis, > ADIS16475_REG_UP_SCALE, > -- > 2.34.1 >
Powered by blists - more mailing lists