On Sun, 8 May 2022 18:55:41 +0100 Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > Discussion of the series: > https://lore.kernel.org/all/20220405135758.774016-1-catalin.marinas@xxxxxxx/ > mm, arm64: Reduce ARCH_KMALLOC_MINALIGN brought to my attention that > our current IIO usage of L1CACHE_ALIGN is insufficient as their are Arm > platforms out their with non coherent DMA and larger cache lines at > at higher levels of their cache hierarchy. > > Rename the define to make it's purpose more explicit. It will be used > much more widely going forwards (to replace incorrect ____cacheline_aligned > markings. > > Note this patch will greatly reduce the padding on some architectures > that have smaller requirements for DMA safe buffers. > > The history of changing values of ARCH_KMALLOC_MINALIGN via > ARCH_DMA_MINALIGN on arm64 is rather complex. I'm not tagging this > as fixing a particular patch from that route as it's not clear what to tag. > > Most recently a change to bring them back inline was reverted because > of some Qualcomm Kryo cores with an L2 cache with 128-byte lines > sitting above the point of coherency. > > c1132702c71f Revert "arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES)" > That reverts: > 65688d2a05de arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES) which > refers to the change originally being motivated by Thunder x1 performance > rather than correctness. > > Fixes: 6f7c8ee585e9d ("staging:iio: Add ability to allocate private data space to iio_allocate_device") > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > Acked-by: Nuno Sá <nuno.sa@xxxxxxxxxx> This crossed with a patch adding another use of IIO_ALIGN in bma400. I've fixed that rename up whilst applying. Thanks, Jonathan > --- > drivers/iio/adc/adi-axi-adc.c | 7 ++++--- > drivers/iio/industrialio-core.c | 4 ++-- > include/linux/iio/iio.h | 10 ++++++++-- > 3 files changed, 14 insertions(+), 7 deletions(-) > > diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c > index a73e3c2d212f..099be9d47223 100644 > --- a/drivers/iio/adc/adi-axi-adc.c > +++ b/drivers/iio/adc/adi-axi-adc.c > @@ -84,7 +84,8 @@ void *adi_axi_adc_conv_priv(struct adi_axi_adc_conv *conv) > { > struct adi_axi_adc_client *cl = conv_to_client(conv); > > - return (char *)cl + ALIGN(sizeof(struct adi_axi_adc_client), IIO_ALIGN); > + return (char *)cl + ALIGN(sizeof(struct adi_axi_adc_client), > + IIO_DMA_MINALIGN); > } > EXPORT_SYMBOL_GPL(adi_axi_adc_conv_priv); > > @@ -169,9 +170,9 @@ static struct adi_axi_adc_conv *adi_axi_adc_conv_register(struct device *dev, > struct adi_axi_adc_client *cl; > size_t alloc_size; > > - alloc_size = ALIGN(sizeof(struct adi_axi_adc_client), IIO_ALIGN); > + alloc_size = ALIGN(sizeof(struct adi_axi_adc_client), IIO_DMA_MINALIGN); > if (sizeof_priv) > - alloc_size += ALIGN(sizeof_priv, IIO_ALIGN); > + alloc_size += ALIGN(sizeof_priv, IIO_DMA_MINALIGN); > > cl = kzalloc(alloc_size, GFP_KERNEL); > if (!cl) > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index e1ed44dec2ab..b4218f3b1ac2 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -1640,7 +1640,7 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv) > > alloc_size = sizeof(struct iio_dev_opaque); > if (sizeof_priv) { > - alloc_size = ALIGN(alloc_size, IIO_ALIGN); > + alloc_size = ALIGN(alloc_size, IIO_DMA_MINALIGN); > alloc_size += sizeof_priv; > } > > @@ -1650,7 +1650,7 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv) > > indio_dev = &iio_dev_opaque->indio_dev; > indio_dev->priv = (char *)iio_dev_opaque + > - ALIGN(sizeof(struct iio_dev_opaque), IIO_ALIGN); > + ALIGN(sizeof(struct iio_dev_opaque), IIO_DMA_MINALIGN); > > indio_dev->dev.parent = parent; > indio_dev->dev.type = &iio_device_type; > diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h > index faf00f2c0be6..c4ce02293f1f 100644 > --- a/include/linux/iio/iio.h > +++ b/include/linux/iio/iio.h > @@ -9,6 +9,7 @@ > > #include <linux/device.h> > #include <linux/cdev.h> > +#include <linux/slab.h> > #include <linux/iio/types.h> > #include <linux/of.h> > /* IIO TODO LIST */ > @@ -657,8 +658,13 @@ static inline void *iio_device_get_drvdata(const struct iio_dev *indio_dev) > return dev_get_drvdata(&indio_dev->dev); > } > > -/* Can we make this smaller? */ > -#define IIO_ALIGN L1_CACHE_BYTES > +/* > + * Used to ensure the iio_priv() structure is aligned to allow that structure > + * to in turn include IIO_DMA_MINALIGN'd elements such as buffers which > + * must not share cachelines with the rest of the structure, thus making > + * them safe for use with non-coherent DMA. > + */ > +#define IIO_DMA_MINALIGN ARCH_KMALLOC_MINALIGN > struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv); > > /* The information at the returned address is guaranteed to be cacheline aligned */
