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dma: fix DMA sync for drivers not calling dma_set_mask*()

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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: Steven Price <steven.price@arm.com>
Closes: https://lore.kernel.org/lkml/010686f5-3049-46a1-8230-7752a1b433ff@arm.com
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/lkml/46160534-5003-4809-a408-6b3a3f4921e9@samsung.com
Fixes: f406c8e4b7. ("dma: avoid redundant calls for sync operations")
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
This commit is contained in:
Alexander Lobakin
2024-05-09 16:46:16 +02:00
committed by Christoph Hellwig
parent 163943ac00
commit a6016aac52
5 changed files with 11 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/dma/mapping.c
View File

@@ -392,7 +392,7 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr)
if (dma_map_direct(dev, ops))
/*
* dma_need_sync could've been reset on first SWIOTLB buffer
* dma_skip_sync could've been reset on first SWIOTLB buffer
* mapping, but @dma_addr is not necessary an SWIOTLB buffer.
* In this case, fall back to more granular check.
*/
@@ -407,20 +407,20 @@ static void dma_setup_need_sync(struct device *dev)
if (dma_map_direct(dev, ops) || (ops->flags & DMA_F_CAN_SKIP_SYNC))
/*
* dma_need_sync will be reset to %true on first SWIOTLB buffer
* dma_skip_sync will be reset to %false on first SWIOTLB buffer
* mapping, if any. During the device initialization, it's
* enough to check only for the DMA coherence.
*/
dev->dma_need_sync = !dev_is_dma_coherent(dev);
dev->dma_skip_sync = dev_is_dma_coherent(dev);
else if (!ops->sync_single_for_device && !ops->sync_single_for_cpu &&
!ops->sync_sg_for_device && !ops->sync_sg_for_cpu)
/*
* Synchronization is not possible when none of DMA sync ops
* is set.
*/
dev->dma_need_sync = false;
dev->dma_skip_sync = true;
else
dev->dma_need_sync = true;
dev->dma_skip_sync = false;
}
#else /* !CONFIG_DMA_NEED_SYNC */
static inline void dma_setup_need_sync(struct device *dev) { }