On Tue, Jun 24, 2025 at 03:39:23PM +0200, Petr Tesarik wrote: > diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst > index 65132ec88104..f5aadb7f8626 100644 > --- a/Documentation/core-api/dma-api.rst > +++ b/Documentation/core-api/dma-api.rst > @@ -308,10 +308,10 @@ action (e.g. reduce current DMA mapping usage or delay and try again later). > dma_map_sg(struct device *dev, struct scatterlist *sg, > int nents, enum dma_data_direction direction) > > -Returns: the number of DMA address segments mapped (this may be shorter > -than <nents> passed in if some elements of the scatter/gather list are > -physically or virtually adjacent and an IOMMU maps them with a single > -entry). > +Maps a scatter/gather list for DMA. Returns the number of DMA address segments > +mapped, which may be smaller than <nents> passed in if several consecutive > +sglist entries are merged (e.g. with an IOMMU, or if some adjacent segments > +just happen to be physically contiguous). > > Please note that the sg cannot be mapped again if it has been mapped once. > The mapping process is allowed to destroy information in the sg. > @@ -335,9 +335,8 @@ With scatterlists, you use the resulting mapping like this:: > where nents is the number of entries in the sglist. > > The implementation is free to merge several consecutive sglist entries > -into one (e.g. with an IOMMU, or if several pages just happen to be > -physically contiguous) and returns the actual number of sg entries it > -mapped them to. On failure 0, is returned. > +into one. The returned number is the actual number of sg entries it > +mapped them to. On failure, 0 is returned. > > Then you should loop count times (note: this can be less than nents times) > and use sg_dma_address() and sg_dma_len() macros where you previously Looks good, thanks! Reviewed-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx> -- An old man doll... just what I always wanted! - Clara
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