Messages in this thread | | | Date | Fri, 10 May 2024 09:12:46 +0200 | Subject | Re: [PATCH] dma: fix DMA sync for drivers not calling dma_set_mask*() | From | Przemek Kitszel <> |
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On 5/9/24 16:46, Alexander Lobakin wrote: > There are several reports that the DMA sync shortcut broke non-coherent > devices. > dev->dma_need_sync is false after the &device allocation and if a driver > didn't call dma_set_mask*(), it will still be false even if the device > is not DMA-coherent and thus needs synchronizing. Due to historical > reasons, there's still a lot of drivers not calling it. > Invert the boolean, so that the sync will be performed by default and > the shortcut will be enabled only when calling dma_set_mask*(). > > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > Closes: https://lore.kernel.org/lkml/46160534-5003-4809-a408-6b3a3f4921e9@samsung.com > Reported-by: Steven Price <steven.price@arm.com> > Closes: https://lore.kernel.org/lkml/010686f5-3049-46a1-8230-7752a1b433ff@arm.com > Fixes: 32ba8b823252 ("dma: avoid redundant calls for sync operations") > Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> > --- > include/linux/device.h | 4 ++-- > include/linux/dma-map-ops.h | 4 ++-- > include/linux/dma-mapping.h | 2 +- > kernel/dma/mapping.c | 10 +++++----- > kernel/dma/swiotlb.c | 2 +- > 5 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/include/linux/device.h b/include/linux/device.h > index ed95b829f05b..d4b50accff26 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -691,7 +691,7 @@ struct device_physical_location { > * and optionall (if the coherent mask is large enough) also > * for dma allocations. This flag is managed by the dma ops > * instance from ->dma_supported. > - * @dma_need_sync: The device needs performing DMA sync operations. > + * @dma_skip_sync: DMA sync operations can be skipped for coherent buffers. > * > * At the lowest level, every device in a Linux system is represented by an > * instance of struct device. The device structure contains the information > @@ -805,7 +805,7 @@ struct device { > bool dma_ops_bypass : 1; > #endif > #ifdef CONFIG_DMA_NEED_SYNC > - bool dma_need_sync:1; > + bool dma_skip_sync:1; > #endif > }; >
very good solution with inverting the flag, Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
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