Re: [PATCH v3 01/20] lib/scatterlist: add flag for indicating P2PDMA segments in an SGL

From: Chaitanya Kulkarni
Date: Thu Sep 30 2021 - 00:47:57 EST


Logan,

> +/*
> + * bit 2 is the third free bit in the page_link on 64bit systems which
> + * is used by dma_unmap_sg() to determine if the dma_address is a PCI
> + * bus address when doing P2PDMA.
> + * Note: CONFIG_PCI_P2PDMA depends on CONFIG_64BIT because of this.
> + */
> +
> +#ifdef CONFIG_PCI_P2PDMA
> +#define SG_DMA_PCI_P2PDMA 0x04UL
> +#else
> +#define SG_DMA_PCI_P2PDMA 0x00UL
> +#endif
> +
> +#define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END | SG_DMA_PCI_P2PDMA)
> +

You are doing two things in one patch :-
1. Introducing a new macro to replace the current macros.
2. Adding a new member to those macros.

shouldn't this be split into two patches where you introduce a
macro SG_PAGE_LINK_MASK (SG_CHAIN | SG_END) in prep patch and
update the SF_PAGE_LINK_MASK with SG_DMA_PCI_P2PDMA with related
code?

OR

Is there a reason why it is not split ?

-ck