Re: [PATCH v4 2/5] dmaengine: sun6i-dma: Support variable address widths using masks

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Low] Local redefinition of standard kernel macros `field_get` and `field_prep` instead of using the generic implementations from `<linux/bitfield.h>`.
- [Low] The newly introduced `field_get` macro is never used.
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commit f2482b50c417768080bd7de168d315dbd88b3be7
Author: Yuanshen Cao <alex.caoys@gmail.com>

dmaengine: sun6i-dma: Support variable address widths using masks

This patch updates sun6i_dma_set_addr() to use masks for high-address bits,
allowing the driver to support variable address widths for newer Allwinner
SoCs. It also introduces local field_get and field_prep macros.

> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index f305fbfb35453..53c54161e32a9 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -24,6 +24,10 @@
>  
>  #include "virt-dma.h"
>  
> +/* Non-constant mask variant of FIELD_GET() and FIELD_PREP() */
> +#define field_get(_mask, _reg)	(((_reg) & (_mask)) >> (ffs(_mask) - 1))

[Severity: Low]
Is this macro actually needed?

Looking through the rest of the patch, field_get() doesn't seem to be used
anywhere.

> +#define field_prep(_mask, _val)	(((_val) << (ffs(_mask) - 1)) & (_mask))

[Severity: Low]
Could we use the generic implementations from <linux/bitfield.h> instead of
defining field_prep() and field_get() locally?

Redefining these core kernel macros creates a namespace collision, bypasses
the standard bitfield type-safety checks, and risks a build failure if
<linux/bitfield.h> is ever included in this driver.

Additionally, unlike the standard kernel macros, these custom versions
evaluate their arguments multiple times.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260826-sun60i-a733-dma-v4-0-dc2f745f40dc@gmail.com?part=2