From: Jonathan Cameron <jic23@kernel.org>
To: "Sa, Nuno" <Nuno.Sa@analog.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>,
Lars-Peter Clausen <lars@metafoo.de>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 03/16] iio: adc: max1027: Push only the requested samples
Date: Mon, 30 Aug 2021 11:07:56 +0100 [thread overview]
Message-ID: <20210830110756.733d5201@jic23-huawei> (raw)
In-Reply-To: <SJ0PR03MB6359415E120CFD3EFAF417F599C19@SJ0PR03MB6359.namprd03.prod.outlook.com>
On Fri, 20 Aug 2021 07:10:48 +0000
"Sa, Nuno" <Nuno.Sa@analog.com> wrote:
> > -----Original Message-----
> > From: Miquel Raynal <miquel.raynal@bootlin.com>
> > Sent: Wednesday, August 18, 2021 1:11 PM
> > To: Jonathan Cameron <jic23@kernel.org>; Lars-Peter Clausen
> > <lars@metafoo.de>
> > Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>; linux-
> > iio@vger.kernel.org; linux-kernel@vger.kernel.org; Miquel Raynal
> > <miquel.raynal@bootlin.com>
> > Subject: [PATCH 03/16] iio: adc: max1027: Push only the requested
> > samples
> >
> > [External]
> >
> > When a triggered scan occurs, the identity of the desired channels is
> > known in indio_dev->active_scan_mask. Instead of reading and
> > pushing to
> > the IIO buffers all channels each time, scan the minimum amount of
> > channels (0 to maximum requested chan, to be exact) and only
> > provide the
> > samples requested by the user.
> >
> > For example, if the user wants channels 1, 4 and 5, all channels from
> > 0 to 5 will be scanned but only the desired channels will be pushed to
> > the IIO buffers.
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> > drivers/iio/adc/max1027.c | 25 +++++++++++++++++++++----
> > 1 file changed, 21 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> > index b753658bb41e..8ab660f596b5 100644
> > --- a/drivers/iio/adc/max1027.c
> > +++ b/drivers/iio/adc/max1027.c
> > @@ -360,6 +360,9 @@ static int max1027_set_trigger_state(struct
> > iio_trigger *trig, bool state)
> > struct max1027_state *st = iio_priv(indio_dev);
> > int ret;
> >
> > + if (bitmap_empty(indio_dev->active_scan_mask, indio_dev-
> > >masklength))
> > + return -EINVAL;
> > +
>
> I'm not sure this can actually happen. If you try to enable the buffer
> with no scan element, it should give you an error before you reach
> this point...
>
> > if (state) {
> > /* Start acquisition on cnvst */
> > st->reg = MAX1027_SETUP_REG |
> > MAX1027_CKS_MODE0 |
> > @@ -368,9 +371,12 @@ static int max1027_set_trigger_state(struct
> > iio_trigger *trig, bool state)
> > if (ret < 0)
> > return ret;
> >
> > - /* Scan from 0 to max */
> > - st->reg = MAX1027_CONV_REG | MAX1027_CHAN(0) |
> > - MAX1027_SCAN_N_M | MAX1027_TEMP;
> > + /*
> > + * Scan from 0 to the highest requested channel. The
> > temperature
> > + * could be avoided but it simplifies a bit the logic.
> > + */
> > + st->reg = MAX1027_CONV_REG |
> > MAX1027_SCAN_0_N | MAX1027_TEMP;
> > + st->reg |= MAX1027_CHAN(fls(*indio_dev-
> > >active_scan_mask) - 2);
> > ret = spi_write(st->spi, &st->reg, 1);
> > if (ret < 0)
> > return ret;
> > @@ -391,11 +397,22 @@ static irqreturn_t
> > max1027_trigger_handler(int irq, void *private)
> > struct iio_poll_func *pf = private;
> > struct iio_dev *indio_dev = pf->indio_dev;
> > struct max1027_state *st = iio_priv(indio_dev);
> > + unsigned int scanned_chans = fls(*indio_dev-
> > >active_scan_mask);
> > + u16 *buf = st->buffer;
>
> I think sparse will complain here. buffer is a __be16 restricted
> type so you should not mix those...
> > + unsigned int bit;
> >
> > pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq,
> > private);in/20210818_miquel_raynal_bring_software_triggers_support_to_max1027_like_adcs.mbx
> >
> > /* fill buffer with all channel */
> > - spi_read(st->spi, st->buffer, indio_dev->masklength * 2);
> > + spi_read(st->spi, st->buffer, scanned_chans * 2);
> > +
> > + /* Only keep the channels selected by the user */
> > + for_each_set_bit(bit, indio_dev->active_scan_mask,
> > + indio_dev->masklength) {
> > + if (buf[0] != st->buffer[bit])
> > + buf[0] = st->buffer[bit];
>
> Since we are here, when looking into the driver, I realized
> that st->buffer is not DMA safe. In IIO, we kind of want to enforce
> that all buffers that are passed to spi/i2c buses are safe... Maybe
> this is something you can include in your series.
Why is it not? st->buffer is result of a devm_kmalloc_array() call and
that should provide a DMA safe buffer as I understand it.
>
> - Nuno Sá
>
> > + buf++;
> > + }
> >
> > iio_push_to_buffers(indio_dev, st->buffer);
> >
> > --
> > 2.27.0
>
next prev parent reply other threads:[~2021-08-30 10:04 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 11:11 [PATCH 00/16] Bring software triggers support to MAX1027-like ADCs Miquel Raynal
2021-08-18 11:11 ` [PATCH 01/16] iio: adc: max1027: Fix wrong shift with 12-bit devices Miquel Raynal
2021-08-20 7:02 ` Sa, Nuno
2021-08-30 9:57 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 02/16] iio: adc: max1027: Fix the number of max1X31 channels Miquel Raynal
2021-08-20 7:03 ` Sa, Nuno
2021-08-30 10:00 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 03/16] iio: adc: max1027: Push only the requested samples Miquel Raynal
2021-08-20 7:10 ` Sa, Nuno
2021-08-30 10:07 ` Jonathan Cameron [this message]
2021-08-30 10:49 ` Sa, Nuno
2021-08-30 14:29 ` Jonathan Cameron
2021-08-30 15:02 ` Sa, Nuno
2021-09-01 8:12 ` Miquel Raynal
2021-09-04 14:06 ` Jonathan Cameron
2021-09-06 8:59 ` Sa, Nuno
2021-09-06 16:56 ` Jonathan Cameron
2021-09-06 17:34 ` Miquel Raynal
2021-08-30 10:06 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 04/16] iio: adc: max1027: Lower conversion time Miquel Raynal
2021-08-20 7:12 ` Sa, Nuno
2021-08-30 10:10 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 05/16] iio: adc: max1027: Drop extra warning message Miquel Raynal
2021-08-20 7:12 ` Sa, Nuno
2021-08-30 10:12 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 06/16] iio: adc: max1027: Rename a helper Miquel Raynal
2021-08-20 7:13 ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 07/16] iio: adc: max1027: Create a helper to configure the trigger Miquel Raynal
2021-08-20 7:16 ` Sa, Nuno
2021-08-30 10:16 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 08/16] iio: adc: max1027: Explain better how the trigger state gets changed Miquel Raynal
2021-08-20 7:17 ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 09/16] iio: adc: max1027: Create a helper to configure the channels to scan Miquel Raynal
2021-08-20 7:18 ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 10/16] iio: adc: max1027: Prevent single channel accesses during buffer reads Miquel Raynal
2021-08-20 7:20 ` Sa, Nuno
2021-08-20 7:30 ` Sa, Nuno
2021-08-30 10:20 ` Jonathan Cameron
2021-09-02 8:56 ` Miquel Raynal
2021-08-18 11:11 ` [PATCH 11/16] iio: adc: max1027: Separate the IRQ handler from the read logic Miquel Raynal
2021-08-20 7:23 ` Sa, Nuno
2021-09-02 8:55 ` Miquel Raynal
2021-09-04 14:08 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 12/16] iio: adc: max1027: Introduce an end of conversion helper Miquel Raynal
2021-08-20 7:28 ` Sa, Nuno
2021-09-02 9:26 ` Miquel Raynal
2021-08-30 10:34 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 13/16] iio: adc: max1027: Prepare re-using the EOC interrupt Miquel Raynal
2021-08-20 7:31 ` Sa, Nuno
2021-08-30 10:30 ` Jonathan Cameron
2021-08-30 10:47 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 14/16] iio: adc: max1027: Consolidate the end of conversion helper Miquel Raynal
2021-08-20 7:45 ` Sa, Nuno
2021-08-30 10:37 ` Jonathan Cameron
2021-08-30 12:44 ` Sa, Nuno
2021-08-30 14:32 ` Jonathan Cameron
2021-09-02 15:12 ` Miquel Raynal
2021-09-03 14:28 ` Sa, Nuno
2021-09-03 14:46 ` Miquel Raynal
2021-09-05 9:41 ` Jonathan Cameron
2021-09-06 9:12 ` Sa, Nuno
2021-09-06 9:30 ` Sa, Nuno
2021-08-18 11:11 ` [PATCH 15/16] iio: adc: max1027: Support software triggers Miquel Raynal
2021-08-20 7:58 ` Sa, Nuno
2021-09-02 12:25 ` Miquel Raynal
2021-09-03 14:20 ` Sa, Nuno
2021-08-30 10:50 ` Jonathan Cameron
2021-09-02 15:21 ` Miquel Raynal
2021-09-05 9:43 ` Jonathan Cameron
2021-08-18 11:11 ` [PATCH 16/16] iio: adc: max1027: Enable software triggers to be used without IRQ Miquel Raynal
2021-08-30 10:54 ` Jonathan Cameron
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