[PATCH v2 00/13] dmaengine: introduce sg_nents_for_dma() and convert users

[Bjorn Andersson]

On Mon, Nov 10, 2025 at 11:23:27AM +0100, Andy Shevchenko wrote:
> A handful of the DMAengine drivers use same routine to calculate the number of
> SG entries needed for the given DMA transfer. Provide a common helper for them
> and convert.
> 
> I left the new helper on SG level of API because brief grepping shows potential
> candidates outside of DMA engine, e.g.:
> 
>   drivers/crypto/chelsio/chcr_algo.c:154:  nents += DIV_ROUND_UP(less, entlen);
>   drivers/spi/spi-stm32.c:1495:  /* Count the number of entries needed */
> 

Comment in patch 1, but for the rest.

Reviewed-by: Bjorn Andersson <andersson at kernel.org>

Regards,
Bjorn

> Changelog v2:
> - dropped outdated patches (only 9 years passed :-)
> - rebased on top of the current kernel
> - left API SG wide It might
> 
> v1: https://patchwork.kernel.org/project/linux-dmaengine/patch/20161021173535.100245-1-andriy.shevchenko@linux.intel.com/
> 
> Andy Shevchenko (13):
>   scatterlist: introduce sg_nents_for_dma() helper
>   dmaengine: altera-msgdma: use sg_nents_for_dma() helper
>   dmaengine: axi-dmac: use sg_nents_for_dma() helper
>   dmaengine: bcm2835-dma: use sg_nents_for_dma() helper
>   dmaengine: dw-axi-dmac: use sg_nents_for_dma() helper
>   dmaengine: k3dma: use sg_nents_for_dma() helper
>   dmaengine: lgm: use sg_nents_for_dma() helper
>   dmaengine: pxa-dma: use sg_nents_for_dma() helper
>   dmaengine: qcom: adm: use sg_nents_for_dma() helper
>   dmaengine: qcom: bam_dma: use sg_nents_for_dma() helper
>   dmaengine: sa11x0: use sg_nents_for_dma() helper
>   dmaengine: sh: use sg_nents_for_dma() helper
>   dmaengine: xilinx: xdma: use sg_nents_for_dma() helper
> 
>  drivers/dma/altera-msgdma.c                   |  5 ++--
>  drivers/dma/bcm2835-dma.c                     | 19 +-------------
>  drivers/dma/dma-axi-dmac.c                    |  5 +---
>  .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    |  6 ++---
>  drivers/dma/k3dma.c                           |  9 ++-----
>  drivers/dma/lgm/lgm-dma.c                     |  9 ++-----
>  drivers/dma/pxa_dma.c                         |  5 ++--
>  drivers/dma/qcom/bam_dma.c                    |  9 ++-----
>  drivers/dma/qcom/qcom_adm.c                   |  9 +++----
>  drivers/dma/sa11x0-dma.c                      |  6 ++---
>  drivers/dma/sh/shdma-base.c                   |  5 ++--
>  drivers/dma/xilinx/xdma.c                     |  6 ++---
>  include/linux/scatterlist.h                   |  2 ++
>  lib/scatterlist.c                             | 25 +++++++++++++++++++
>  14 files changed, 51 insertions(+), 69 deletions(-)
> 
> -- 
> 2.50.1
> 
>