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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4562e89c308sm88278035e9.30.2025.07.18.14.18.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jul 2025 14:18:51 -0700 (PDT) Date: Fri, 18 Jul 2025 22:18:50 +0100 From: David Laight To: Jonathan Cameron Cc: David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iio: proximity: isl29501: use scan struct instead of array Message-ID: <20250718221850.614d05b3@pumpkin> In-Reply-To: <20250713150445.3965931c@jic23-huawei> References: <20250711-iio-use-more-iio_declare_buffer_with_ts-7-v1-1-a3f253ac2e4a@baylibre.com> <20250713150445.3965931c@jic23-huawei> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 13 Jul 2025 15:04:45 +0100 Jonathan Cameron wrote: > On Fri, 11 Jul 2025 11:18:13 -0500 > David Lechner wrote: > > > Replace the scan buffer array with a struct that contains a single u32 > > for the data and an aligned_s64 for the timestamp. This makes it easier > > to see the intended layout of the buffer and avoids the need to manually > > calculate the number of extra elements needed for an aligned timestamp. > > > > Signed-off-by: David Lechner > Why are we using a u32 here? It's a 16 bit > read in that isl29501_register_read() call > and storagebits = 16 in the chan spec. > > So to me looks like you found a bug for big endian platforms. Maybe not - it looks like there is a read on one place and write in another. Both are passed the same address. The interface looks very strange though. But the updated code is writing uninitialised stack. David > > --- > > drivers/iio/proximity/isl29501.c | 9 ++++++--- > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/iio/proximity/isl29501.c b/drivers/iio/proximity/isl29501.c > > index d1510fe2405088adc0998e28aa9f36e0186fafae..0eed14f66ab700473af10414b25a56458335b381 100644 > > --- a/drivers/iio/proximity/isl29501.c > > +++ b/drivers/iio/proximity/isl29501.c > > @@ -938,12 +938,15 @@ static irqreturn_t isl29501_trigger_handler(int irq, void *p) > > struct iio_dev *indio_dev = pf->indio_dev; > > struct isl29501_private *isl29501 = iio_priv(indio_dev); > > const unsigned long *active_mask = indio_dev->active_scan_mask; > > - u32 buffer[4] __aligned(8) = {}; /* 1x16-bit + naturally aligned ts */ > > + struct { > > + u32 data; > > + aligned_s64 ts; > > + } scan; > > > > if (test_bit(ISL29501_DISTANCE_SCAN_INDEX, active_mask)) > > - isl29501_register_read(isl29501, REG_DISTANCE, buffer); > > + isl29501_register_read(isl29501, REG_DISTANCE, &scan.data); > > > > - iio_push_to_buffers_with_timestamp(indio_dev, buffer, pf->timestamp); > > + iio_push_to_buffers_with_timestamp(indio_dev, &scan, pf->timestamp); > > iio_trigger_notify_done(indio_dev->trig); > > > > return IRQ_HANDLED; > > > > --- > > base-commit: f8f559752d573a051a984adda8d2d1464f92f954 > > change-id: 20250711-iio-use-more-iio_declare_buffer_with_ts-7-880ddf1d3070 > > > > Best regards, > >